"But seeing they could not See; hearing they could not Hear"
“The views expressed herein are those of the author and do not necessarily represent those of the National Weather Service or affiliate/related organizations. Please consult .gov sites for official information”

"From its chamber comes the whirlwind, and cold from the scattering winds." - Job 37:9.

"The wind blows to the south and turns to the north; round and round it goes, ever returning on its course".

Monday, August 30, 2010

Small Portion Of Southeast Florida Gets Pounded By Rains

(Image: Rain shower moving onshore Cocoa Beach early Sunday Morning)
RECAP: Rain showers eventually hit a broad expanse of landscape yesterday across South and Central Florida with most totals below 1/4". On the other hand - - Polk, Hillsborough, and Pinellas Counties further west received some reports of over 1 inch while extreme eastern portions of Palm Beach and Broward Counties had much higher totals. The overall winner of the blue ribbon goes to a small area in Palm Beach County where the last total which came in was from Boynton Beach at 5.77" shortly after 10pm last night. It's likely that this total is closer to 6" by now though as rain was still falling in the vicinity at 11pm. There might have been a break in the action over night, but when I woke this morning a weak convergent band was pressing onshore very near there from the east...but with closer investigation it appears that this band might be just south of Boynton Beach toward Delray Beach.  It was quite bizarre to watch radar animations yesterday, as the very select area being impacted by the persistent rains, and at a few times pretty intense lightning storms simply could not penetrate west of perhaps 20 miles of I-95. They would get so far and simply erode while in the meantime the storms kept regenerating just to the east over and over again.  I noted yesterday via radar loops and infrared satellite imagery that a weak sfc-mid level low seemed to form off the coast of Vero which moved almost due south (off shore) with time.  The biggest storms near Boynton went up ahead of this feature in the early evening producing quite a bit of lightning, but they moved very little if at all.  Since then, that circulation is not apparent at this time.  Otherwise this morning, there was another streamer of showers coming in very close to Miami as well as one just barely making it on shore close to Jupiter Island. Elsewhere, rains have been moving in on western portions of the Panhandle and a very weak squiggly line of rainshowers, perhaps not even reaching the ground were crossing Volusia County near Daytona. Their latest surface observation did not indicate even light rain, even though radar shows a tiny green reflection right over the airport.
TODAY: Really not much to talk about for MANY days to come (but see the TROPICS para). As noted above, there were two distinct convergence streams in progress impacting solely SE Florida, not to discount the lowers keys though from roughly Islamorada west. High pressure will reign supreme up and down the entire Eastern Seaboard of the U.S. For the most part, all of Central Florida will be rain free today under the influence of a drying air mass and a fresh easterly wind.  Rains over SE Florida will gradually shift further south and west during the day. This could take quite a while folks from Boynton Beach south to south of Miami and into the Kendall area will continue to receive rains and some thunder until at least midafternoon...eroding from the north with time as we work into the evening.  Toward the west side of the state, some showers and thunderstorms will again be possible from Tampa Bay to south of Naples...right along the west coast.
TONIGHT-TUESDAY: There is some indication that a few patches of atmospheric moisture could move across the state any time between 7pm tonight to before noon tomorrow. Even if this materializes, the worst we would see from this is enhanced periods of cloudiness and a very light, short period spritz of rain but in general partly cloudy will prevail.
WEDNESDAY - AT LEAST SATURDAY: Generally dry across the boards, especially for the immediate Central Florida area. See more under the TROPICS portion.
TROPICS: Hurricane Earl as of 8am was strengthening with winds of 110mph. Motion is officially WNW at 14mph, but when I looked at radar animations from Puerto Rico the eye seemed to moving move toward the NW rather than WNW. But in general a WNW to NW variable track will continue today. Extreme NE PR will be coming quite close to experiencing hurricane force winds later today into tonight, especially over the higher terrain on that side of the island near the Air Force Station at Roosevelt Roads to Fajardo and Rio Grande. Folks in the condos in those regions toward San Juan will be in for an interesting experience tonight into early tomorrow.
Earl's Future Track: No need for Florida to fret, but unlike Danielle, Earl will come close enough (to the far Eastern Bahamas) to have a direct meteorological and oceanic impact.  Upon Earl's approach to the far eastern Bahamas Florida we could receive one last short-lived swap of moisture wrapping around the periphery outside the subsidence zone surrounding the storm late Tuesday. This would be of very short duration though...and shower chances from this are very low end. These would be of low topped nature and not thunderstorms except maybe near the Keys or extreme SW Florida. As we work into Wednesday surface winds might become light and variable for time..but generally from the east. Eventually winds will take on a more assured NNEly component as Florida enters the 'zone of subsidence' around the system. It is while we are in this zone that seas will be at peak performance, with rip currents and wave action being more pronounced than those ever with Danielle.  Additionally, Earl could be just as strong or even stronger than Danielle during its passage east of Florida. Over night temperatures may seem a little unusually warm as will daytime high temps, especially on Thursday and Friday.  To mention in passing, high temperatures might get near records values as winds take on a more NWly component. Rain chances during this time will essentially be zero. I expect folks will want to flock to the beaches, especially from the Cape to Jacksonville to view the waves under such benign weather conditions coupled with the press amping up the storm up, especially if the anticipated strengthening of the system materializes which could take it up to Category 4. But in speaking from experience, there will be little to see, but watching the surfers, especially on Thursday morning, could be fun where the waves break just right. Not anticipating erosion issues at this time in other words. I'd head to Sebastian or Spanish House hopes that waves bouncing off the jetty do not make First Break a washing machine. Further north along Satellite Beach at the old RCs break might be quite nice as well as at New Smyrna Beach, all contingent upon timing of the tides with a gradually backing surface winds (to offshore) from Wednesday into Thursday and maybe early Friday as the system pulls further north.
The bigger story for Earl will be, and for the most part already is, its brush with the coast from Hatteras - Maine. Not one model this morning brings the system fully onshore, as an upper level trough will gratefully be passing across the Great Lakes region and heading toward the coast in perfect timing to perhaps be a saving grace from total mayhem. With that said, Earl is going to be the irritating clown in the dunking booth...taunting and teasing local weather forecasters up and down the mid-Atlantic to New England Coast line as to just exactly how great the storm's direct impact will be.
INVEST 97L: This system is nothing more than a big forecast headache for now, so won't elaborate much. This is the system that is not so fondly already being referred to in some circles as Fiona. I liked "Friona" better. As a friend pointed out to me, Friona, TX was hit by a tornado many years ago that made for some great video. I have it in the collection somewhere. As mentioned yesterday, the ECMWF brought this system into East Central Florida, but a later run took it completely SOUTH of the state. Now, last night's run takes it on a course similar to Earl's whereas the GFS still does not develop the system at all beyond a 'depressed' state (not named). The NAM run shows a similar tendency. If this is to be the case, the system would not pose any threat whatsoever in any form to the U.S. Thus, at this point, until the system becomes even better organized and gets a distance away from Earl any talk is total conjecture. At this point, the system is pretty darned close to Earl, so I can see why the NAM and GFS, and to some degree that latest ECMWF are depicting what they do. It's still early morning though as of this writing, so it will be interesting to see what the 12Z (8am) runs are showing later this morning.

No comments:

Sunday, August 29, 2010

Not a Beach Day!

(Image: An ocean shower off East Central Florida Saturday Afternoon)
RECAP: Weather evolved yesterday pretty much as expected, ending with a bang near Tampa Bay around 11pm. Otherwise, the only real precipitation that did develop was along an apparent thermal gradient boundary, perhaps enhanced by the geography of the Cape during the late afternoon hours. The boundary developed as a result of extensive cloudiness across the north 1/2 of the state which was referred to yesterday morning which never dispersed during the course of the day. South of the clouds the surface temperature really heated up with very light winds even along the coast. The temperature at one point on my porch was up to 94 degrees which is nearly 10 degrees warmer that points further north and under the clouds. The rain showers set up running ENE-WSW over North Cape through Titusville and into Orange County. One heavier shower rolled easily along and south of the boundary seemingly hugging the thermal gradient as it rolled into extreme NE Osceola County. Elsewhere, the storms of the day much later were from near Naples to North Tampa Bay with the majority of them not really getting going until they were just off the west coast other than near Tampa Bay and Port Charolette where they experienced a heavy storm late in the evening. There was one rampant storm over Ft Lauderdale though with a reported wind gust of 43mph in the late afternoon which quickly 'dispersed' as it moved off toward the SW Coast.
SYNOPSIS: Strong high pressure along the U.S. East Coast from New England to South Georgia impinging on the Florida NE Coast this morning. Showers and a few lightning strikes have occurred well offshore the Florida East Coast which to this point have generally remained in the same place but are slowly spreading west toward the coast from Jacksonville to just south of West Palm. A few showers have already made it on shore of light-moderate intensity.  Meanwhile, the low pressure area in the Gulf came ashore in a much weakened state on extreme SW Louisiana and is now moving northward around the western periphery of the high pressure system. Satellite imagery also depicts another mid-level cyclonic circulation of weaker organization moving rapidly north through East Central Mississippi with an attendant surface boundary extending East then SE from it which is now crossing Central Alabama. This is the old stationary boundary that was across I-10 yesterday.  Meanwhile, the high pressure over the mid-Atlantic states centered near Virginia is working south along the coastline.  There is a concentrated area of enhanced moisture along the leading edge of this 'backdoor front' as it works toward the SW which is still offshore Central and South Florida as of this writing, however a convergence boundary seems to be getting established over immediate Ft Pierce. Moderate-heavy showers have been continuously redeveloping at that point.
There was somewhat of a surface wind 'surge' of sorts over portions of East Central Florida early this morning accompanied by some brief rain showers which developed as a result of outflow from collapsing storms well off shore. This 'surge' of sorts has since passed well to the West of the immediate coast. Winds picked up for a good hour during its passage with some gusts just over 20 mph right along the A1A corridor, and since that time have remained a bit stronger on the beaches than what they were at sunrise. They seem to be dying down though even more as I write.
TODAY: For the most part the more focused area of showers and a few lightning strikes will remain offshore, but continue to impact the Ft. Pierce area for a while longer. In the meantime, the leading edge of higher pressure where the deepest moisture is concentrate will be forced on shore during the early afternoon, roughly sometime between 1:00-3:00pm.  Just because this moisture will be moving over does not imply that it will rain everywhere that it exists overhead. As is often the case with a moist and steady onshore flow...very thin convergent/concentrated moisture bands can set up resulting in a steady stream of showers in one locale while nearby the sun will remain shining or nearly so. This is already in process ...and with some more heating of the day combined with short term visible satellite imagery loops (movies) these boundaries will become any such boundaries will become more evident. The best chances of rain today outside of what is occurring now for Central and South Central East Florida will be from 1:30pm -9pm this evening with clearing from north to south as we head toward sunset and into the overnight hours. Again, some folks might not see rain at all today whereas others might see quite a bit. Outside of any bands that might happen to set up (these are not guaranteed) there will be a wide spattering of rampant, light showers across the peninsula. Not expecting thunder and lightning today over the majority of the state other than extreme Southwest Florida on the west side of Lake O and points west to as far north as the immediate Tampa Bay where their morning sounding came in quite unstable once again.
TONIGHT INTO TOMORROW: The very thin moisture surge will pass west and south of Central Florida during the night and into early tomorrow and exist primarily from St. Lucie County and points south along the East Coast initially and into Okeechobee, Martin, and Palm Beach Counties. As the day progresses it will continue SW and thin out, exiting the state by late evening. In it's wake is much drier air through the atmosphere with the only moisture remaining in the lowest levels. As such, by tomorrow afternoon expecting only a few very isolated, light low-topped showers to move onshore north of this boundary toward the Cape which will not make it much further west than the US1-I95 corridor. The likelihood of even these renegade showers will henceforth decrease even more by late afternoon with remaining rains and possible thunderstorms all south of Central Florida and will be focused primarily over the extreme western portions from Sarasota and points south by late evening.
TUESDAY-FRIDAY: Looks dry with seasonable temperatures and weakening surface winds. But, see the TROPICAL section below.
TROPICS: Hurricane Danielle is long gone...but the long duration offshore swells continue, creating very hazardous swimming conditions due to the rip currents produced by them. Those, along with the ever present possibility of rain showers and off/on periods of cloud cover along the coast will not make for a good beach day. In Cape Canaveral this morning the waves did not look impressive to any degree whatsoever..but that's Cape Canaveral for you. There is no erosion occurring. There was a drowning yesterday 1 mile south of PAFB (Satellite Beach) of a 'surfer' as has been widely publicized by the news media. Another one was up at Ocean City. I'd be willing to bet he wasn't a very experienced 'surfer', but regardless anyone should take heed if planning on entering the water today despite the less than favorable weather conditions for even being on the beach in the first place.
EARL: Shortly before beginning to type this morning's post, Earl was officially proclaimed a hurricane as it approaches the northern Leeward Islands. Virtually every model is forecasting a curve to the NW right as it bears down on Puerto Rico. I'd be willing to bet that the island could experience some Tropical Storm force winds...but it will be close. It IS worth watching Earl despite the forecasts to see if it starts to take the curve or not, because if it actually crosses the island and continues a WNW course that would mean it will be in the process of diverting the split in the ridge to its north which has been enhanced by Danielle's passing. If it does this all forecasts as to its future track can be thrown out with the trash...but as is forecasted officially by the Hurricane Center and all models there has been no change in thinking as to the storm taking the curve. There has been debate amongst the models as to just how close this storm will approach the coasts of N. Carolina up to New England though and the jury is still out on this to some degree. For the most part it appears, as things stand now, that Earl's biggest threat to the U.S. Mainland will be larger and more treacherous surf conditions than those posed by Danielle as we head toward Wednesday. Folks from Hatteras to Cape Cod need to keep watching this sytem, flat out.
If Earl does indeed stay off shore as forecast, it will be closer to the U.S. than Danielle ever was with similar intensity, hence the waves and rip tides will again be of prime concern. Assuming it passes in such proximity, the weather over Florida would remain very dry and possibly quite warm under subsidence surrounding the storm as winds become light and eventually NNE then NNW-W as it gets north of our latitude here in Florida.  This could play havoc for lifeguards! With such benign weather occurring and warm temperatures...the flocks could be heading for the cooling ocean waters to get the toes wet. Hope they don't do anymore that soak the toes though...lest they get 'undertowed'.
WILL THERE BE A FIONA TOO?: Starting to look that way. In fact, as I posted to Facebook this morning, last night's ECMWF Model actually brings what would be Storm Fiona onshore East Florida very near Satellite Beach in Brevard County on the evening of September 6th. That's 'hurricasting' for you. At one point, the GFS model brought what was yet to be even named Danielle into Daytona Beach.  Also, the latest track models take this Invest along a course similar to what is being currently forecast for Earl. It wouldn't hurt to point out though that this year the Euro and to some degree the Canadian models have had a better track record on the tropics this year than the GFS one. Which reminds me, last night's GFS model does not even acknowledge the existence of a named Fiona, but rather loosely associates it with Earl as a 'tag along' entity. This seems pretty darned unlikely seldom if ever does this occur. Hence, and as noted a few posts ago, what is now being labeled as a 'vigorous tropical wave' may soon be declared a depression later today which would henceforth be named "Fiona" if what is being consensually forecast by other models materializes.

No comments:

Saturday, August 28, 2010

ENE Flow Regime Slowly Becoming Established Today

(Image: Forecast of surface features for Sunday morning from the 8pm run of the NAM are depicted)
RECAP: Glad there was an update to yesterday mornings post because the early-late evening rainfalls definitely occurred over portions of Central Florida yesterday/last night. The heaviest storms were over portions of Lake County and western Orange County with one report of 4.23" which came in from Winter Garden in Orange County....and a special weather statement of a possible funnel was disseminated for one of the Lake County storms. Elsewhere, almost all of Osceola County was eventually encompassed with a broad area of light-moderate rains.  There was one lone heavy shower that passed over North Brevard near Mims/Titusville before sunset. Further west much more rain was to be found with big totals. Some of these rain remnants eventually piddled to the east coast providing for a few rain spits along the immediate coastal communities around midnight. Other activity formed along the immediate east shores of Lake Okeechobee during the mid afternoon hours.
SYNOPSIS: Most notable features this morning are the ever expanding/strengthening high pressure centered over Virginia and a surface/mid-level low just off the Louisiana coast which first made its presence known yesterday along that inverted trough which was extending from the low in the far SW Gulf.  The hurricane center has outlined this low with a very low probability of further tropical development, and all models are depicting this to be the case. Extending from this low is what remains of the stationary boundary which has been over Southern Georgia for quite some time now.  The old circulation of what I've been referring to remnant TD5 is finally gone, or perhaps is what generated that low off Louisiana. Probably not, but just like the number of licks it takes to get to the center of a Tootsie Pop...the world may never know (who cares anyway...right?). This boundary has sunk south a bit and is now roughly located right along I-10. The southwest flow aloft is gone now for the most part..and mid-level winds over Central Florida are very light. 
LOCALLY: There also appears to be a weak disturbance riding ENE across N. Central Florida  along or just south of the weakening stationary frontal boundary which is accompanied by a fairly extensive deck of cloudiness across the same area from near Brooksville on the West Coast to Ormond Beach on the East Coast. This area of clouds is trying to penetrate toward Orlando but seems to be getting eroded from the bottom up as it reaches Orange County. Further north it is making it to the coast though. The high pressure ridge that was over the Florida Straits is almost overhead and in the process of merging with the high pressure circulation over the mid-Atlantic. I haven't seen a morning sounding as it was not available but I'd be willing to bet that winds wise there isn't much to see that would sway me from making the following forecast for the daylight hours of today.
SYNOPTIC OUTLOOK: The low south of Louisiana will push toward the coast right about where SE Texas and SW Louisiana meet. This will force the stationary frontal boundary northward along with abundant moisture into southern Louisiana, which for the most part has already begun. Hence, some big rains over the toes of the Big Boot State are on-going late this morning and will continue to do so through the day and evening. Meanwhile, further east high pressure will strengthen more along the Northeast and mid-Atlantic coast and expand southward. In turn, the far eastern portion of the stationary boundary along I-10 will inversely push SWard toward the Florida NE Coast and eventually the central portions of the coast over night tonight.  This boundary will washout over southern portions of the state on Monday as the high pressure comes fully under control  by mid-day Monday for the entire peninsula except extreme SW portions.
TODAY: Surface winds across the entire state to assume a generally ENE-Eerly wind component at the surface while mid level winds become light and variable over Central Florida. There is still plentiful moisture. Believe the easterlies will become somewhat enhanced during the afternoon which will be most notable along the A1A corridor up and down the entire Florida Coast which will push without hindrance toward the west half of the state during the course of the day. As such, storms, some with very heavy rains and frequent lightning, will mostly likely affect the Western Half of the state from the Everglades northward to just west of Orange County and over the Tampa Bay region, although western Lake County can't be fully counted out for some of this activity. Expect most of the show to commence in the mid-late afternoon with max storm coverage running from right before sunset through midnight. Further north toward Jacksonville the stationary boundary will start to enter the Jacksonville area as it begins a SSW trek down the coast to well offshore.  Thus, extreme NE Florida will be in the 'muck' of clouds and rains for most of the day.  From Daytona Beach south to Miami it will be a pleasant day other than some rampant coastal showers moving on shore, particularly south of West Palm. Unlike the past two evenings, the activity to the west will not spread eastward. Therefore, for the most part all of East Central/South Florida will remain dry all day into tonight.
OVERNIGHT INTO SUNDAY: NOT a beach day from Brevard and points north tomorrow but nice for the attractions inland. The backdoor boundary of sorts will remain to the north, but slowly increasing easterlies off shore could push some nocturnal rain showers on to the coast from the Cape northward. The likelihood of this evolution increases around sunrise and increases even more as we work toward noon. The front shown in the attached image which was derived from the NAM model is probably a little over done, but you get the gist. It's likely this boundary will never make a clean passage over the area at the surface, but rather simply become absorbed in the deepening ENE-E flow aloft late in the day.  The morning NAM is consistent though with maintaining somewhat elevated rain chances  throughout the daylight hours from Brevard County northward. This does not appear to be an all day rain event, but more of an occasional shower event whereas areas to the west are much more likely to remain dry.  By late in the day showers will spread WSW to the west coast. The best chance of thunderstorms tomorrow will likely be right along the SW Coast of the state where a late afternoon sea breeze could develop and thus low level convergence is established.  It won't only be the chances of rain showers that won't make it a good beach will also be the rip currents and ugly surf (as far as swimming is concerned).
SUNDAY NIGHT INTO MONDAY: The surface boundary, or what remains of it washes out to South Florida while lingering moisture and an onshore wind component maintains a possibility of nocturnal rain showers making landfall all along the east coast which could penetrate well inland. Monday could start out showery but that chance decreases by late in the day.
TUESDAY-THURSDAY: Pretty darned uneventful with rip currents being the big weather story. Actually, by around Wednesday - Thursday what will be Hurricane Earl could be close enough to the east to place much of the state in subsidence around the storm's periphery making for less clouds but warm inland temperatures.
FRIDAY-NEXT SUNDAY: Watching the next tropical system to rotate around the Carousel of Storms which models are portraying to be Storm Friona. Lips might be pursed and brows furrowed as forecasts are showing this system to become quite strong as it approaches the U.S. Coast.
TROPICS/SURFERS: Hurricane Danielle is out of the picture weather wise, but the swells from this storm are beginning to impact the east coast. Looks like the peak of the swells will be later this afternoon into early tomorrow. SURFS UP GUYS! Unfortunately, onshore winds will not provide for the primest of conditions, so hit it early especially Sunday and Monday. It will be totally ride-able though for many days to come so stock up on the Sex Wax.
With Danielle eventually accelerating off to the NE in the open Atlantic eyes will be on what looks to be Hurricane Earl by this time tomorrow. Earl is forecast to move just north of Puerto Rico Sunday into Monday and slowly begin a more WNW (and eventually NW) curve as it does so. The GFS is forecasting Earl to strengthen significantly as it passes north of the island and heads toward the extreme SE Bahamas. The curve would be due to a weakening of the high pressure ridge to its north created by Danielle. If forecast trends continue the ocean swells will be more direct, and thus more impressive than those of Danielle along the East Coast from Florida-Hatteras. Thus, after a decline in the surf early in the week it will again pick up with Earl.
Now, the next pony on the carousel is forecast to be what would be named Friona. This will be THE STORY OF THE DAY if all amounts to what models are depicting. Each successive storm is inching closer to the U.S., and Friona is no different. As it stands now the big threat will be directly on the Carolinas-Virginia. But we know how that goes. Heck, the system as a named entity exist yet...but my bet is we will hearing the name over the air waves within 72 hours. For now it is being described the the Hurricane Center as a "vigorous disturbance". Don't know how 'vigorous' a disturbance can be..but with a high likelihood that it will organize into a tropical low...I guess this cuts the mustard better than describing it as 'mild'.

No comments:

Friday, August 27, 2010

Early Afternoon Update For Florida Readers

(Image: Latest KSC sounding available on the net at 11am, Friday)
NOW: Included in this post is the latest KSC Sounding. Inspection of the sounding coupled with the morning model runs pretty much keeps the previous discussion on status quo. The exception is that there is pretty significant drying of the atmosphere with the PWAT having fallen from 1.97" to 1.79". Also, the 700mb temperature has gone up a degree as the low level inversion slowly erodes.  As expected, the ENE-NE winds at the surface have developed across much of the eastern half of the region, but the weaker midlevel WSW winds aloft continue but mainly over the what I'd consider to be in the upper portions of the mid-levels.
UPDATE FOR TODAY: Hence, expect no rain activity along a diffuse sea breeze boundary early in the afternoon...with a continued chance of storm development after peak heating (i.e. - after 4:00pm). From this time on storm height and coverage will increase with many areas not receiving any rain, whereas other areas will experience a brief period of very heavy rains with lightning. Unlike the earlier post, now looking at activity to once again make a late exit entirely from the area...last affecting the coastal communities as late as midnight. Orange and Seminole Counties seem to be the mostly likely areas to have the greatest rainfall totals when all is over with due to lingering activity.
SATURDAY: Looks like there could be a bit of a break in activity for Central Florida, but entirely so. In other words, no change yet in philosophy
SUNDAY: Fly in the ointment doing the breast stroke. Pattern reversal as expected with showers first coming onshore as soon as the pre-dawn hour which spread in coverage and intensity and coverage as the push toward the WSW across the spine of the state toward the west coast late in the afternoon. More showers could come on shore through the day on Sunday...but we can look more into this possibility as time goes by.
COASTAL CONCERN: Strong rip tides and high surf. Peak looks to max out on Sunday afternoon through most of Monday then be slow to wane into midweek. At time, no expecting any significant erosion for the surf.  Seas will once again pick up, maybe more so around Thursday. Erosion might be more of an issue which I'm sure the pros in the NWS are watching.

No comments:

Mid-Late Afternoon Showers and Storms Possible Again Today

(Image: Enhanced infrared satellite image shows lows in the SW Gulf and off Louisiana; Hurricane Danielle and TS Earl)
RECAP: Rains were late to get going yesterday under the canopy of mid-level clouds that just wouldn't break lose. It appears that a few things kept storms from developing robustly yesterday. Firstly, the cloud cover kept temperatures below the convective temperature during the day and also from breaking entirely the low level inversion which was referred to in yesterday morning's post. Additionally, it appears a bubble of surface high pressure developed over East Central Florida which was slow to move offshore. We also never really had a true sea breeze circulation yesterday. Granted, an easterly low level easterly flow did develop before noon time, but this really wasn't a true sea breeze. This was easily seen when considering the fact that the easterlies developed almost uniformly across the entire Central Peninsula at the same time, rather that as a 'sea breeze front' created by temperature variations between land and sea. With very light easterlies being overrun by very moist WSW-SW winds at the mid-levels the altocumulus deck was further enhanced and become self-perpetuating. By early evening the bubble high had moved well offshore coincident with an upper level vorticity max which crossed the North Central Portion of the state from west to east. As such, by early evening thunderstorms and showers were wide spread from mainly Daytona Beach northward.  As the high moved further off and lost its grip the first heavy shower over the immediate Central Portions crossed downtown Orlando. This was followed by more activity over SE Osceola and extreme Southern Brevard. Eventually a larger area of moderate showers lined up approximately 30 miles either side of a line along the Beach Line from Brevard through Orange and Seminole Counties..and points even west of these locales, while more rains continued to the north near Ocala and Gainesville in the 10-11pm time frame. Other storms were located just east-NE of Lake O in Palm Beach County. The whole kibosh has since then moved east this morning.
LOCAL SYNOPSIS: The vorticity max and associated weak surface low (well east of Jacksonville) is off shore, and a lingering line of showers and storms trails from the low SSWard to right on the coast at West Palm Beach. Meanwhile, another bubble high has formed in its wake over Central Florida. The timing has been just right to clear out the cloud deck which has been in place for a couple of days now. Additionally, the light winds and clearing skies have given way to the coolest morning we've seen across the entire northern 1/2 of the state than we've seen in maybe two months ...except the western 1/2 of the Panhandle. KSC sounding is showing similar mid and upper level temperatures to yesterday and the day before, with not surprisingly an inversion in the low levels. The inversion could be a reflection of the bubble high over the area in the wake of the 'system' that has moved off shore. The air mass is still quite moist, despite the nearly clear skies at time of writing, misleadingly so...with a convective temperature around 90-91 degrees. Sure looks stable out there right now as of 8:45am.
ELSEWHERE: As was thought a possibility, that low in the far SW Gulf referred to yesterday has become a big player. Indeed, there continues to exist an inverted trough extending from this low which is now hugging the Mexico Coast which extends NNE-NE-ENE-Eward into a developing low centered just south of Louisiana. Both lows (the one off Mexico and the other off Louisiana) are easily seen on the color enhanced infrared satellite image included with this post. This boundary continues ENE toward the old circulation over SW Georgia where it merges with what was the cold front which was moving east of the Mississippi River Valley region yesterday morning. Meanwhile, broad area of high pressure continues to build into the Mid-Atlantic Region from the west. This inverted trough (actually becoming a stationary front from the low south of Louisiana) will remain in place today with little change. The low south of Louisiana will likely strengthen further at the surface and midlevels and move west, paralleling to and just south of the Gulf Coast states...but likely bring some significant rains to the TD Landing Strip of Southern Louisiana into Mississippi/Alabama today along the stationary front extended E-ENEward from it.  Under this scheme of things, most of peninsular Florida remains in a no-man's land with a surface ridge axis extending still across the southern portion near Lake O and the mid-level axis extending from the Western Atlantic to just along or north of the Florida Straights. With all this going on, winds in the mid-levels remain from the WSW but to less a degree than the past few days.
TODAY: Believe the bubble high will push offshore during the course of the day. Very light NW winds to mostly calm winds for that matter at the majority of locales at 8am will give way to light NE-E winds by 9-10am.  A light to moderate WSW prevails aloft just above the inversion level through 20,000 ft. Without the cloud cover present today, that convective temperature of 90-91F will be reached almost anywhere today...particularly along and west of I-95. Showers could form as the easterly component wind from the eastward moving bubble high is enhanced by somewhat of sea breeze with better heating of the day. The wind should remain light and variable along the coast, then initially become NE-ENE and veer more toward the east or maybe ESE as the sea breeze develops and moves inland. Not expecting much low level convergence (showers) to form along the boundary as it develops due to the continued presence of the by-then eroding inversion. Cumulus cloud field will form between 12 -2pm in the meantime and become more enhanced throughout the day with prolonged heating. Showers could eventually start to go up in earnest in the 1:30-3:00pm time frame first along the pseudo-sea breeze front then inland as well. Once shower/storm tops grow to efficient heights while the bubble high is well out of the picture all activity should begin an E-ENE motion toward the coastal locales specifically north of Ft. Pierce.
Much further north, even though this region is closer to the stationary frontal boundary, convergence for north central Florida looks weak and remaining cloud cover should keep this area more stable. The areas most likely to receive thunder today should be roughly south of Brooksville on the West Coast to Daytona on the East Coast. Convection (and thunder and lightning producing activity) will be enhanced as it first penetrates the sea breeze front just west of I-95 from near Oak Hill to Ft. Pierce, with another area of enhancement along the eastern shore of Lake O toward West Palm possible. This area remains the 'sticky spot' due to the greater influence of the high pressure ridge nearly overhead and stronger easterly component surface winds. It will by no means rain everywhere today, and it's more likely that many areas will not get wet than will.
Unlike yesterday, shower activity should move offshore without lingering affects as was expected yesterday...with most of it gone by the 9-10pm time frame.
SATURDAY: Leaving this "in general" mode for now. The Northern Gulf surface low will retrograde westward toward the Texas Coast and pull the lingering surface boundary (stationary front) with it as high pressure becomes more of the dominating force, more notably by very late into the day or evening.  Meanwhile, winds aloft at the mid-levels will become increasingly lighter and the overall air mass will dry a smidge. Exactly how things will evolve tomorrow remains uncertain, but at time looking for a lower possibility of rain...which is less likely to be of the thunderstorm variety except over south Florida and the W-SW coast, particularly from just south of Sarasota through Ft. Myers.  Meanwhile, high pressure will strengthen with its center at the surface and mid-levels over Virginia. More of an easterly flow regime will become established by evening.
SUNDAY: Continued morphing of an easterly flow regime on this day, and watching for a mid level and to some degree a low level wind surge early in the day accompanied by low level speed convergence and resultant shower activity which would most likely affect the coast from Ft. Pierce to Jacksonville. This could continue through early portions of the day with a break during the late morning to mid-afternoon hours, then become somewhat enhanced once again later in the day as the mid-level surge moves overhead. Timing is completely sketchy as to this evolution though, and as such should be taken with a grain of sea salt.
MONDAY - THURSDAY: Easterly flow in full swing. The amount of lingering moisture is in question, but for the most part should play of little consequence for the weather across the majority of the state other than the areas along SW Florida east to the region south of Lake Okeechobee where showers and storms will remain a possibility around the periphery of the high as well as perhaps some influences of tropical nature (inverted trough).
TROPICS: Category 4 Danielle making a beautiful satellite presentation this morning as it 'eyes' Bermuda. It looks like that is all it will do though...since curvature toward the N and eventually NE before reaching this island is becoming increasingly likely. Namely due to the high pressure over Virginia which will remain in place combined with the strong upper level trough aloft and its accompanying SW-NE steering winds developing just ahead of the system.
Elsewhere, TS Earl and what looks like an errant nephew storm continue further to the east and south of Danielle and are not players until at least mid-week of next week. Earl could pose a more interesting forecast problem as we head toward Thursday as it looks now. But not so much as if it will rain, but more likely in how nice it will be here. Still, can't jump to any conclusion quite these two entities bear watching.
The big concern for these little gems will be rip currents and large surf! Swells from Danielle then stacked with those of Earl could keep the surf up for a good 10 days at least and the risk of rip currents/undertow/rip tides...however one prefers...will be highly elevated and of big concern along the entire US East Coast, especially since this activity will be picking up during the soon to be weekend time frame.

No comments:

Thursday, August 26, 2010

COULD Be Widespread Thunder For a Select Florida Area Today

Image: Storm focused mainly over N. Merritt Island yesterday made for a brief but pleasurable viewing experience along A1A in Cape Canaveral
RECAP: Very moisture laden SW-WSW mid-level flow pattern prevailed yesterday across Central Florida with the largest of storms over N. Merritt Island where a break in the cloud deck permitted the best surface heating. Lightning was hard to come by elsewhere other than further north toward Daytona. I was honestly surprised to see that Vero Beach reached 95 degrees yesterday! Just thought we could throw that in for good measure. Heck, the Miami area had a record high on Tuesday of 95 as well. So the summer of record highs (as well as record warm minimum temperatures) combined with prevalent warm mid-upper level temperatures continues.
SYNOPSIS: It's a mid-level features day for sure! Surface ridge axis extends from S of Bermuda across S. Florida to southern portions of Okeechobee County, whereas at the mid-levels it remains over the Florida Straits.  Mid level and surface low is pulling off the extreme NE U.S. Coast with an accompanying surface cold front reflection trailing SSW  to North Central Georgia where it starts to meet up with, yes...what I've been very loosely describing as remnant TD5 from over a week now! I've seen no discussions concerning this particular feature but have been eyeing it ever since the TD came ashore. It never lost some semblance of circulation at the 850mb level since that time, therefore I fondly refer to it as such.  A very weak surface and mid-level low, as it is, remains over extreme SW Georgia.
On the other hand, the surface low over the extreme W. Gulf is drifting south to almost the northern portions of the Bay of Campeche. This is interesting because there is a weak surface and mid-level reflection of an inverted trough extended NNW-WNW from this low to the low in Georgia. North and west of this trough a very strong and broad area of high pressure is encompassing much of the Eastern 1/4 of the country including the western Florida's only the peninsula that remains in warm, moist conditions until one heads west into S. Texas over to Arizona. It was COLD this morning in Minnesota, Michigan, Iowa, and Wisconsin with wide spread lows in the 40s and even a few upper 30s in North Wisconsin and Michigan. UGH! These cold temperatures are behind a dry cold front that is approaching the NE and Mid-Atlantic coastal region this morning.
...LOCALLY: Again, surface high pressure ridge extending from the Atlantic toward or just north of Lake O. Latest LDIS plots and surface obs indicate that there could be a weak boundary emanating from the low in the far SW Gulf across Tampa to the Space Center (aside from the more pronounced trough going into SW Georgia). Latest sounding data just came in confirming a continued SW-WSW flow just above the surface but weaker than the past few days. Temperatures aloft have changed nil from yesterday with 500mb near -5C and 700mb near 7C, with a PWAT just over 2". There is a bit of an inversion (and drying) near the standard  950mb level (500-1500 ft) which is right where cumulus clouds would form. It will take a while for this inversion to work out. Little change in the overall lay-out will occur today, other than that the mid-level ridge over the Florida Straits will move a bit further north toward the tip of S. Florida, and the very weak surface 'boundary' right across the center of the state will likely disappear with daytime heating, as will the aforementioned inversion. So things will start out very slowly with nothing to speak of across all of Central Florida.
TODAY: Opting to paint a 'worst case' scenario as far as potentially wet conditions are concerned despite how things currently look (as noted above). Might do an update when this scenario does not unfold though. As mentioned yesterday and based on latest model data, it does indeed appear that a sliver of strongest mid-level WSWterlies exists right over the immediate Central East Coast over Brevard County. Further south they are much weaker to almost nonexistent. Therefore, with some daytime heating believe the sea breeze will most assuredly develop first from near West Palm south (under the very weak mid-level flow) with a slight delay further north toward Brevard and points north. The sea breeze should make it as far west as Lake O further south then make less inland progress the further north one gets. Near South Brevard it will just barely make it to the Osceola County border and will likely impinge just barely west, if even, of US1 by the time one gets north of Melbourne...the US1-I95 corridor seems to be the breaking point the rest of the way up the coast to Jacksonville.
As was the case yesterday, a lot of what will occur in the early afternoon is contingent upon how much the mid-level cloud deck can break up. It will not break entirely...but there could be just enough of one to occur for another storm or heavy shower over N. Merritt Island to develop once the sea circulation develops sometime after 1pm. One developed there yesterday even without the sea breeze in play (might also point out this is a very localized 'playground affect' for shower and sometimes funnel clouds to form).  After this point expect further spotty showers and a larger Cumulus cloud field to form over all of the peninsula as we enter the peak heating hours (early-mid afternoon). 
Clouds should start to congeal into showers and eventually thunderstorms almost anywhere over the East half of Central and South Central Florida...but the further south one gets, especially near Lake O the further west the storms will form. Outflow from a storm over N. Merritt Island (if this does occur) will abet in aiding a localized enhancement of storm development further to its west and south along and west of the sea breeze front toward Seminole, Orange and Osceola Counties as well as northward into Volusia. This activity will move generally ENE-E in the prevailing mid-level flow and perhaps be further enhanced as it meets the pre-established sea breeze front, particularly from St. Lucie County north to Jacksonville. All this will occur later in the afternoon (after 3:30-4PM)...first affecting the inland portions.  Regeneration of showers and isolated thunder could continue, particularly over Central and North Brevard for quite some time due to remnant outflow interactions and/or remnant inland storm activity drifting toward the coast. As long as we're painting this 'worst case for wet' scenario, might as well go full bore in stating that the last of the rain...or probably more likely...a denser mid-level cloud deck..would be last to clear the coast in an area roughly outlined from near Oak Hill to Satellite Beach but well east of downtown Orlando-Sanford area south toward Deer late as 11pm tonight. 
As you can see, a lot could happen today over the most eastern portions of all of Central Florida..particularly from Volusia County south through St. Lucie County. Further south of there (which is Martin County)..things get very difficult to ascertain, especially if one assumes a good Lake O breeze develops. But do believe that any activity from Martin into PB County will be a "one time shot sometime late this afternoon deal", if at all.
FRIDAY: Synoptically speak...not a whole lot to go on. Mid-level flow will weaken even further and remaining cloud cover (regardless of what does or doesn't occur today) will be problematic. Similar sea breeze set up though but perhaps making it further westward than it will today. Chances are that storm probabilities will be officially be above average for this one last day.
SATURDAY-MONDAY: Point blank, BIG problem, but no big deal when push comes to shove. The cold front never makes it here, but rather the brunt of its force gets carried offshore north of the state as the big high pressure area broadens its expanse across all of the east 1/3 of the U.S initially. It looks now as though the high pressure will make its final build from the NNE and down the Florida east coast sometime late Saturday toward Sunday...sufficient moisture will still abound for at least clouds to exist in the meantime...and a final surge of NE-ENE winds at the mid levels will make head away around the ridge and onto the the Florida east coast as a 'backdoor' cold front. Convergence along this surge could provide enough lift for coastal showers to move in, first by Jacksonville Beach then southward with time to as far south as West Palm. This will occur sometime over the weekend, but timing at this point as to just when this will occur remains sketchy at best.
BEYOND MONDAY: We're in 'it' for the long run. "IT" being deep ENE-E flow with cooler coastal temps (below 90F) and no thunder pretty much everywhere expect for maybe a brief period along the immediate SW Florida Coast near and south of Ft. Myers.  Tuesday through next Friday will be defined by this uneventful, first signs of early fall flow pattern.
BEYOND NEXT FRIDAY: High pressure remains in control under thunderstorm shut-down mode, but transitioning to an early fall- onshore tropical 'like'' mode with coastal showers becoming an increasing issue. By later Thursday or Friday we might need to start watching for inverted troughs to impinge on the coast from the Cape and points south to the Keys under the base of the prevalent high pressure area extending across the mid-Atlantic states. Further north additional cold frontal blows will cross the Great Lakes region and the NE states and be of no impact locally.
TROPICS: By now most folks (or at least any one who reads this) knows about Hurricane Danielle and it's tease with Bermuda. Believe the high pressure area and preceding front will be enough to divert this storm from the island in the nick of time, but I bet the folks living there aren't taking it so lightly and will be on the edge of their seats until the storm makes a definitive turn.  Erstwhile, TS Earl could become a hurricane as well. It's course is less certain...despite the fact the models divert this system as well...don't be too quick to judge. But I'd place my bets on that becoming a reality. It's what comes next which would eventually be Friona that I'd be watching. As we work toward next weekend the strong high pressure over the mid-Atlantic states could work further east and prevent future tropical storm development from heading toward Santa's Palace...placing a larger threat on Puerto Rico and the Dominican Republic. This would be as we approach mid-September and the peak of Hurricane Season.

No comments:

Wednesday, August 25, 2010

Potentially Interesting Forecast Days Through Saturday

(Image: Sunrise on this date one year ago near the Cocoa Beach Pier)
RECAP: Deep, moisture laden SW-WSW flow prevailed yesterday with a few rampant rumbles of thunder, but for the most part rains were light of stratiform (non-cumuliform) nature. Eastern portions of Central and SE Florida from near West Palm to Ormond Beach had their 'peak experience' between 1pm -4pm followed by a broad expanse of stratiform type rains from Indian River County toward Daytona to the north to the west coast. This activity was enhanced through the early-late evening over far eastern portions of Central Florida due to a vorticity max the moved slowly offshore extreme North Brevard. As such, there was very light rain reports continuously for 4-6 areas over this area.  This morning it was primarily Palm Beach County and areas to the WSW that were under a stratiform shield all morning..that very light rain is quickly coming to an end.
SYNOPSIS: Weak area of low pressure continues near the Georgia/Alabama border (southern most parts) at 11:30am with a quasi-stationary boundary snaking roughly WSW and ENE-E ward from it. Ridge of high pressure continues over the Florida Straits. The strongest of WSW winds at the mid-levels seems to be over E. Central Florida with winds in that elevation nearly 30 knots uniformly from the WSW. Finally have a chance to see the KSC sounding again today and things have changed. Both the 700mb/500mb level temperatures have dropped roughly 2C degrees from the past two weeks.  Convective temperature is 88 degrees which we will just barely reach, and if we do it won't be until at least 2pm due to the nuisance mid-level cloud deck overhead much of the state. Another weak surface and mid-level low is persisting in the far west-central Gulf as alluded to yesterday in the tropical portion of the post. This feature will unlikely form into a tropical entity, but it's continued presence will serve to exasperate the forecast as we work into the Friday/Saturday time frame (see more on this below).
TODAY: Given the current synoptic set up combined with the latest sounding, satellite, radar data...much of Central and South Central Florida could have moderately strong thunderstorms today (due to down draft winds in and very near heavy rainfall); the clincher is the mid-level cloud deck which will put a damper on what would otherwise be some down right decent instability due to its preventative surface heating properties.  Indeed, in the pocket least covered by clouds earlier today a thunderstorm went up without hesitation during the last hour over Volusia County just north of Oak Hill. Observed earlier today as I was outside was a low altocu deck of clouds with little white tufts on top of them (wanna be altocumulus castellanus)...indicative of some rising air in that layer and instability. Upon seeing this cloud formation I was eager to see the KSC sounding. In fact, some of these cloud patches showed up on radar as light rain (even though there was none to be felt on the ground).
Believe that some patches of thunderstorms will eventually form, although any thunder will be isolated.  But any storms that can manage to eke out could be strong, particularly between the hours of 2:00pm -7pm.  I'd be watching the sky towards the WSW today during that time frame if you're looking to avoid rain an not having an umbrella handy.  Inland folks, don't forget to look up too...showers could form directly overhead.
Storms could be much stronger today if (1) we got a light sea-breeze to work, (2) the mid level clouds were not out there. But such is not the case, so "The Summer of 2010 - A Tale of Weak Storms" (not to discount the handful that has occurred) will continue otherwise.  The mid-level clouds and thus lack of surface heating also prevents the lake breezes to function in full - - one additional defunct in the thunderstorm producing machine today.
If one isn't in or near a thunder producing storm today, it will be just 'another cloudy', muggy day that could eventually end up in 'drip drip drip' mode by dinner time....just like the last two. Interestingly, though, the NAM shows that convective precipitation could pile up along the East Central Florida Coast during the early evening whereas the RUC shows virtually NADA pretty much everywhere. I'm hedging more toward the RUC solution but not in full. At least not as of 11am...the folks in south Brevard toward West Palm might be the ones getting the 'real rains' when all is said and done. We shall see.
THURSDAY: WSW - SW flow will be in the process of pulling out during the course of the day. Mid-upper level clouds will once again be a big factor for determining the eventually meteorological outcome for the remainder of the day. More cloud cover would mean less destabilization and weaker low level convergent boundaries off the larger lakes as well as the strength of the sea-breeze. Models are insistent on keeping a narrow swath of 15-20kt winds just above the surface over East Central Brevard tomorrow...such a narrow slot that it's probably negligible. Still seems assured the sea breeze will form south Sebastian-Vero..but further north it's  touch and go. Don't think we'll see as much cloud cover in the morning tomorrow (or Friday) just might be one of our last big fling days at our chance for a good summer thunderstorm  over coastal East Central Florida for the year.
FRIDAY-SATURDAY: Mainly putting these two days together because it is this time frame that things get SO sketchy. The NAM, and to some degree the GFS, indicate that  weak surface-mid level lows could form off the Central Florida East Coast at the tail end of the stronger mid-level southwesterlies as they pull out. The other low is depicted somewhere along or near the Gulf Coast of the western Florida Panhandle.  As mentioned earlier in the synopsis, this low seems to be generated from an inverted trough extending from the low in the far western Gulf toward the Mississippi River mouth or just east of there. Thus, the longer that Gulf low persists without moving into Mexico or near Brownsville..the more we'll have to watch for this possibility. The most pronounced one at this time is the Atlantic low. The past couple of runs of the GFS were showing continued rain chances for extreme eastern portions of Central Florida with little explanation as to how this could be other than that the moisture we have had lately remains in place longer than what one would normally expect...but now there is another reason why rain chances might continue for a bit longer. This would likely not be of thunderstorm nature though regardless..particularly on Saturday. We're going to have to see what comes out of the upcoming situations before digging into this presented 'forecaster grave'. (ie., shooting myself in the foot).
MONDAY - MOST OF NEXT WEEK: By this time whatever does (or doesn't) form off either coast should be out of the picture as we shift into a different mode through much of the first week of September along the Florida East Coast. Don't like it..but the first signs of early fall and the end of the daily thunderstorm cycle mode are showing their signs of coming to a fatal demise. We have one more chance of this type of day for the 'afternoon cycle' to occur as it looks now...but that's still at least a week away beyond Friday.  Otherwise, we shift into more of an early fall mode, where our most significant rainfall events are of tropical (directly or indirectly generated) origin. After about September's more toward South Florida and the West Coast.
TROPICS: Watching Danielle, and soon to named Earl, then perhaps Fiona in the next 72 hours or so.  The GFS run over night was plain crazy. Clustering all 3 systems so closely together that none of them gains a winning hand and keeping them at Cat 1 or perhaps 2 strength or less. Additionally, it took Danielle into New York City!..interesting possibility, but remember, earlier this same model took what was yet to be Danielle into Daytona Beach.  Note: that is not a forecast, just an observation. The system in the Gulf is no threat to Florida or anyone for that matter, other than an open handed slap in the face for maybe some flooding near the Texas/Mexico border coast...but that is yet to be seen or forecasted.

No comments:

Tuesday, August 24, 2010

Strong SW Flow To Continue Through Wednesday

SYNOPSIS: Not much appreciable change from yesterday as moderate to strong SW flow in the mid-upper levels is in full swing. A surface front is roughly stringed across South Central Georgia while a surface ridge axis remains well to the south over the Florida Straits. Mid-Upper level winds are from the WSW-SW and jet stream level winds are starting to join the bandwagon between the squeezing influence of these two features. Deep moisture streams across the North Central through South Central Peninsula and slightly drier (but not dry) air resides over extreme South and North portions. Mostly cloudy with a few patches of partly cloudy skies prevail under the strong SW-WSW wind corridor.  Elsewhere, a weak surface mid-level low has formed in the West Central Gulf. No significant strengthening of this feature is anticipated.
TODAY: SW flow aloft prevails under partly to mostly cloudy skies during the late morning to early afternoon, becoming mostly cloudy-cloudy by late afternoon.  A rapidly weakening band of moderate rain showers is entering Orange County down through Polk and moving steadily ENE-NE ward. Expect this area to continue spreading across the state as we work toward noon...thus many areas in the north halves of Polk/Osceola/Brevard up toward Seminole, Lake, and Volusia will be encompassed by light to moderate rains eventually. The heaviest rain will be encountered along the leading edge of this rain area.  Mid-upper level temperatures have cooled a degree or two as anticipated yesterday...seemingly just enough to keep the cloud cover intact yet not enough for strong updraft generation. Thus, not expecting any sig storms today yet...but some imbedded thunder is not out of the question after 1pm. With the strong mid level winds now in place, the heaviest rain showers could be accompanied by wind gusts in the 40mph range. Will be watching the immediate coastal areas from just north of West Palm on up I95-A1A toward Ormond Beach though since the rain shield arrival (assuming it makes it this far) will be preceded by a longer period of data 'heating'...or what little there is under these mostly cloudy skies...which could provide some fuel for regeneration of showers/storms along the leading edge. The heaviest storms will likely be mid-late afternoon today further north toward Volusia and Flagler Counties and inland near the big cities of Ocala and Gainesville.
TOMORROW: Not much change as the current synoptic set up remains status quo over the SE States. Most certainly another post will be needed to refine the details though since the amount of lingering cloud cover will play a crucial role in rain shower development/intensity. Also to  watch will be any upper level vorticity linger over or near the state.
THURSDAY: SW flow not so quick to move out as earlier suppositioned! The main reason this is important is the strength of the flow will be crucial for determination of when, where, and how strong the sea breeze will be or form. Currently it appears that a sea breeze could form but would remain very close to the coast (along or east of I-95). If so, we could see some stronger storms along the coast from near West Palm to Ormond.
FRIDAY: Continued uncertainties..but most assuredly the strength of the SW flow will have waned considerably by this time with sea/lake breezes circulations at play for yet another challenge to mix into the forecast equation.
TROPICS: Hurricane Danielle looks to be weakening slightly at this time but of no concern no matter how you slice it.  We may soon be looking at an Earl in a day or two...and even perhaps Fiona after that. Meanwhile, it wouldn't hurt to watch the West Central Gulf and who knows...maybe even the Central Gulf by this time tomorrow. There are no indications right now that anything significant will develop in this area at time...but as the mid-level trough axis gets get off and lingers over this region things could at least get a little interesting to glimpse at during the next 48 hours.

No comments:

Monday, August 23, 2010

"Watch This Way" (from the SSW-SW)

(Image: Classic KSC Cape towering shower forms yesterday as sea breeze develops. We've seen them much larger than this one yesterday...but this was a nice reminder that waterspout producing showers can and do form in this area)
RECAP: Big rainfall totals yesterday for the West Central Portions of the state with Polk and Hillsborough Counties overall being the leaders of the pack with one isolate Orange County report, with one total over 5" near Tampa. Other high totals came in from Lakeland, Plant City, Winter Haven,  Bartow, Bloomingdale to name just a few. On the east coast we had only light totals with nothing on the intracoastal. Once the day evolved and the sea breeze set up everything generally moved from NE to SW...piling up over Polk County toward Sarasota while skies elsewhere became partly cloudy. Tower clouds went up over the Space Center with a possible funnel sighted there around noon, but the confirmed reports were from near Naples and just off the Keys.
SYNOPSIS: Surface trough lies across Southern Ga/Al/Miss. with high pressure ridge as far south as Cuba. Low pressure resides over the Northeast states extending down the East U.S. Coast through South Carolina with an additional reflection into Georgia. Mid-Level low has taken shape well off the coast of Ft Myers. Deep, moisture laden SSW-SW flow from the surface to 700mb is in the process of establishing over all of Central Florida with the outliers being extreme the SE portion and the Panhandle. This pattern will strengthen throughout the next 24-36 hours and become potentially quite interesting Tuesday. The KSC Sounding data is finally available this morning. It shows generally a SSW-SW steering flow with continued warm air aloft with 700mb near +10C and 500mb near -4 or -5 (in other words, no different from what it's been for a LONG time).
NOW-MID AFTERNOON: Surface winds over much of Central Florida are generally from the S-SSW. Gradient flow will likely prevent formation of a true ECSB (East Coast Sea Breeze) today from Volusia County south to between West Palm/Jupiter. Line of sustaining showers extends from north to south from north and over Lake Okeechobee...with a cloud line extending from the north end of the this shower line northeastward toward the Cape Canaveral Port Entrance. Light showers are forming as I write along this cloud line as well. Aloft, high level cirrus clouds across the north half of Brevard toward Orlando are being generated from activity off the South Carolina coast which is streaming overhead due to NE jet stream level winds. These high clouds are currently putting the breaks on cumulus development over said region, however more clouds/showers could develop here as well, maybe even before I finish typing this late morning blog entry.
The aforementioned shower line morph in size,intensity, and northern extent as it moves toward the NE-NNE during the course of the next 2-3 hours into Osceola, Indian River, and South Brevard Counties. Anyone in this region up to maybe north central Brevard might or might not see some rain before 2pm as a result.  Meanwhile, other showers could form along the cloud line extending toward the Port...with all other areas slowly filling in with showers.  From noon to 3pm more showers/storms will likely fill in across Central Florida making timing for a shower for any one locale impossible to determine. Motion of activity will be from the SW "watch this way". Anvil level winds will continue from the NE so the cirrus from activity will stream back from the direction of motion during the day...but this will be changing as we head toward Wednesday.
MID-AFTERNOON THROUGH EVENING: Some areas by this time may have received rain more than once today. Showers will move right along so large accumulations not expected. By 2-3pm I'd be watching a lot more for lightning from activity though. A lot of what occurs later today will be contingent of what results with the early afternoon activity. Lots of remnant cloud debris could aid to stabilize the atmosphere...but believe that as the SW flow strengthens, mainly from Oak Hill south toward Vero that we might see a stronger round of storms during this time frame into the evening hours. Also to watch will be the amount of cirrus clouds steaming across the region off the Carolina/Georgia Coasts. These could inhibit late day destabilization. Additionally, without a sea breeze convergence boundary setting up not expecting giant storms...other than a few in isolated pockets...but just where this could occur at this time of day would be like picking B9 out of the bingo ball stir pot on the first try.
Further north toward Daytona to Jacksonville. Sea breeze could set up in this region with light gradient mid-level flow overhead. However, this region is closer to the deepening mi-level activity could be more robust along the coast up that way which is a bit closer to the surface boundary.
TOMORROW: More changes at hand. The surface boundary will sink a tad further south to just about the FL/GA border as the mid-level low over the Carolinas deepens and closes off. Gradient mid-level flow over the immediate Central Florida region will strengthen to 25-35mph just over head with ample moisture. Due to deepening of the mid-level trough temperatures aloft might decrease a degree or two...but nothing overly significant is anticipated aloft over Central Florida...north Florida folks will need to be watching this though, as storms up that way could be quite strong as a result from Flagler County toward Jacksonville and inland toward Gainesville and perhaps with Ocala being on the southern fringe of these affects.
Otherwise, synoptically speaking...winds the whole way up to jet stream level (25K-30K feet) will change to a westerly direction along with the maintained SW-WSW mid level flow direction. As a result, storms will move even more quickly tomorrow with no sea breeze most assuredly. Temperatures aloft will maybe a degree or two cooler...and pockets of mid-upper level vorticity will be passing over the region. Thus, I maintain a high level of chances for convection on Tuesday..particularly from near Ft. Pierce and points north to Jacksonville along the East Coast...and from Ft. Myers and points north on the West Coast..then everywhere in between. We'll see how things develop during the course of tonight for yet another post tomorrow. One thing to watch though for now, now that I think about it, is that any robust storms tomorrow could have strong winds associated with them due to the stronger mid-level winds.
WEDNESDAY: A little bit like today all over again as mid -upper flow weakens to some degree. Ample moisture once again abounds. Whether or not a sea breeze will develop on Wednesday is tricky. One might develop late in the afternoon as mid level gradient flow will be weakening during the day. Otherwise, still looks like there will be storms in the same place as Tuesday.
THURSDAY-SATURDAY: Continued weakening of mid-upper level flow with a gradual 'normal' sea breeze / outflow boundary collision pattern re-establishing. Not so sure about the A1A corridor though as far as rain chances go..but as we work more toward the weekend coastal storms look less likely.
SUNDAY: We'll see. The last GFS run I saw is sticking with the deep Easterly flow pattern setting up as alluded to yesterday..but for some reason it has the Cape in a precipitation bulls-eye..which sure isn't dry like it seemed it would be yesterday. It's only Monday now we'll see.
TROPICS: Danielle will probably be a hurricane by noon out in the Atlantic. On a side note, the GFS last night was showing a storm/hurricane to form off the N. tip of the Yucatan and brought it  to North Central Florida by September 4th. Not showing anything remotely close to that now though..just thought I'd throw that out there.

No comments:

Sunday, August 22, 2010

Boundary/Sea Breeze Front Collision Convection Day In Store

Image: Looking west across the Banana River toward US1 at storms that lined up along the US1-I95 Corridor yesterday. This image shows the outflow developed gust front that moved across the A1A corridor associated with those storms to the west. Also of note, anvil level winds steering storm tops away from the coast, keeping the sky blue until the storm is nearly right on top of any affected area.
RECAP: After posting yesterday morning it became apparent that East Central Florida had drawn the Tarot Card with an umbrella on it from the deck. It was mentioned that early morning convection was on going over West Central Florida to near the Lake County Area. The convection never made it further east as was suspected and in fact these storms eventually collapsed and scoured out much of West Central Florida; however, once we had some daytime heating and a cumulus cloud field formed it was easily apparent through watching the visible satellite imagery animation that a great outflow boundary from that collapsed convection was spreading rapidly ESE across the peninsula. As it progressed across the state the east coast was sitting pretty with the normal noon time sea breeze beginning to slowly develop. Some good cloud lines initially developed over the Space Center south over Cape Canaveral but nothing came out of this activity. Once the sea breeze developed in earnest which was by 1pm these clouds dissipated and further development along its leading edge to the west. Steering currents were weakly from the north the sea breeze took its time working west across the rivers and made it about as far west as somewhere between US1 or I-95. Meanwhile, the aforementioned outflow continued through the Orlando area and met the sea breeze right along that corridor. As such, storms rapidly developed in a North/South line the entire length of Brevard County beginning around 1:30pm dumping over 2" of rain over many areas. With the steering currents nearly paralleling the coast this activity was hard pressed to cross the waterways in earnest. As a result, rainfall totals were significantly lower out on the barrier islands, although the entire spectacle was fun to watch out there at a 'safe' distance from the lightning (see image included in this post).
SYNOPSIS:  As of 9am it appears that East Central Florida is in somewhat of a mid level COL with low pressure over the mid-Atlantic to the NE states and well to the south of the state. At the same time high pressure is well off the east coast with another area extending into the Gulf from a core right over the Central U.S. states.  The Central and Southern Peninsula in general are not being directly affected by any of these features this morning. As such, surface winds are land breeze generated and winds aloft are all less than 10 kts, but generally from the north. The area most in this indefinable wind field predicament appears to be, of all places, Brevard and Indian River Counties. I haven't been able to obtain a sounding from KSC for two days now, at least not before making a blog post. Yesterday's finally came out well after the post, but even so probably would have been of little use considering the circumstances that developed. Given water vapor imagery though and current forecast trends, see no reason that there is not abundant atmospheric moisture to work with again today coupled with the standard warmer than normal mid-upper level temperatures.
NEAR TERM SYNOPTIC FORECAST:  Based on model trends/forecasts for the past 2 days and continuity believe that much of the peninsula will eventually be under a very broad mid-level area of low pressure at the base of the trough now running down the U.S. eastern seaboard through the NE and mid-Atlantic states by day's end during the course of the day. As such, a trough axis will eventually develop which at this time appears will be running from near Daytona Beach SW to just south of Sarasota by mid-day Monday...after which a very discernible steering flow will be established.  Steering currents today will remain very very weak to non-existent in the meantime, with a NE wind at the upper most limit aloft of the steering current level. Anvil level winds will remain from the NE as they have for days. But until then...
TODAY: With the scenario painted out 'as such' above, the local forecast for much of East Central Florida and much of South Florida is quite the quandary at this time of day with no synoptic scale features at hand to work with. Will the same thing happen today as yesterday?  Highly unlikely. There was a lot of storm activity along the west coast this morning over Tampa and points south like yesterday, but this activity is moving generally toward the SSW (off their coast over there) and has pretty much all but ended now for that entire region. More will be revealed once cumulus clouds start to form in earnest, but that is still another hour from now. As such:
Expect east coast sea breeze to once again form on queue between 12:00-1:00pm. It should be slow to migrate west once again with no help from upper level winds to either enhance it nor pin it on the coast either.  With ample moisture around...and perhaps even more at the low levels once the sun gets beating under nearly clear skies due to transevaporation/transpiration from already rain soaked grounds...the cumulus field will start to develop most noticeably after the thin land strips of the Space Center, near larger inland lakes, and along the shores of the intracoastal as early as 10am. As these clouds gain a little substance and merge rain showers will eventually form just about anywhere with very little motion. Clouds will grow most formidably along the developing, light sea breeze and move very little. It will be interesting to see what the west coast sea breeze does today, especially after all the rain shower activity they've had over there this we'll have to be watching that.
Wherever, showers and perhaps some lightning develops during the 10am-3pm time frame..they should remain fairly isolated without broad 'expansial' coverage. With additional heating of the day the atmosphere over the peninsula will become increasingly unstable and rising thermals will give way to further cumulus cloud development over the entire peninsula except behind the sea breeze. I'm going to watching the KSC toward the port though. With almost no winds aloft and rapid rising thermals...who knows.
Once we reach the mid-late afternoon just about anywhere could get a storm as boundary collisions occur from collapsing earlier activity and peak instability is reached. Toward evening, as the mid-level trough axis becomes established a bit of a push toward the east will be develop mainly south of Daytona Beach-Miami.
ENOUGH FOR TODAY: In short, Monday-Tuesday look to be days with enhanced flow from the SSW-SW with showers/storms most likely in the afternoons/evenings on the east side of the state south of Flagler and perhaps most of Volusia well as early morning activity around Tampa Bay.
WEDNESDAY-THURSDAY: Transitioning back to more of normal wind field pattern as mid-level gradient flow relaxes.
BEYOND: Thunderstorm shut down. Dryer, stacked easterly flow becomes established as high pressure builds eastward from the Central U.S. states over the mid-Atlantic region and off shore that region.

No comments:

Saturday, August 21, 2010

Showers/Storms Unlikely East of US1/I-95 for Central Florida Today

(Image: A weak outflow boundary approaches Cape Canaveral late yesterday from a storm that was nearly 30 miles away and collapsed. This is the affect that occurs when winds just above the sea breeze boundary are from the west..but just above that level they were keeping storms well inland (from the north)
Leaving this one brief, as there is a very large disparity between my line of thinking and what I'm reading/seeing through media/internet outlets.
TODAY:  First off, sure hope I'm wrong about all this (below). We need some storms along the immediate coast. But...
To be brief, think the chance of coastal rains from Ft. Pierce to Daytona look pretty darned meager today. Showers and storms are approaching N. Lake County at time but having an impossible time penetrating further east than where they've reached the past 2 hours. Model guidance and latest MAPS forecast sounding data indicate continued warm air aloft today...and getting warmer aloft as the day goes by as steering winds veer more northerly to even the NNE by late. Thus, believe most activity that goes up along any sea breeze collision which will go up west of I-95 will be pushed S-SW and away from the coast during the early evening hours toward The Big Lake and along the west coast from Tampa-Ft. Myers.
Outside of sea breeze activity, other showers could go up near the Orlando area - Volusia County before noon due to outflow from early convection to the northwest of there..this activity could push SE-ESE initially while it remains low-topped..any robust activity though that could generate lightning will likely start to drop due southward.
Late morning activity still has a chance of forming along the east shores of Lake O near I-95/US1 though in Palm Beach-Dade County...but that should be few and far between. Further north in Central Florida...any rains in this region would have to occur between 11:30am-2pm right before and as the sea-breeze develops. Should be scoured out though by 2:30pm if there is any at all for that matter. Also, by this time high level clouds could have impinged from storms that have generated way out over the Atlantic this morning. Actually, the more I look at it even late afternoon/evening activity chances do not look too great any where. Surely someone will get the boot, but don't think it's going to be anywhere in Brevard/Volusia/or Indian River Counties.
SUNDAY: For now, looking at slightly better rain prospects..but not by much.
LATE SUNDAY- TUESDAY: For now seems to be the best chance of rain/storms for the East Half of the entire state. Models are STILL having a hard time coming to anything close to agreement...but they are getting there.
LATE WEDNESDAY-NEXT WEEKEND: So far...looks like all convection will be west of an Orlando - Lake Okeechobee Line as high pressure builds across the mid-Atlantic Region. Will watch for the possibility of nocturnal shower activity to begin for the immediate A1A corridor areas along all of the Florida East Coast as this time frame approaches.
TROPICS?:  Still not much going on.

No comments: