Nate's Fate (or Lack Thereof) Grows Uncertain By The Hour - And Maria?

Analysis From www.spc.noaa . gov   , The Storm Prediction Center. This nformation is extrapolated from trends, observations, and the RUC Model (without going into the finer details). This Image shows a 'disturbance' or vorticity maximum (max) crossing Central Florida. After which, things will be quite calm for a majority of the day, East Central. Another disturbance is shown to cross Central Florida During the afternoon (lower left). South Florida will remain the most unstable throughout the day, while north of the Purple area some recovery from passage of the first disturbance will take all of the afternoon to accomplish. In short, rain chances end up occurring in the same places and at the same time as yesterday for the day with some minor differences.

TODAY/FLORIDA: A disturbance is crossing Central Florida now but you'd never know it from looking outside. In its wake will be some minor drying in one atmospheric level and NVA (negative vorticity) and subsidence over Central Florida. South Florida will not contend with this settling of the atmosphere and will grow increasingly unstable during the afternoon, although the level of instability attained yesterday so far does not look to be as great as yesterday to start with.


Meanwhile, further north the passage of the boundary shown in orange above continues to impact North Florida. In fact, Tallahassee last hour was 56F degrees and Crestview was 59F. Many other readings hovered close to 60F this morning with much drier air. This influx of lower dewpoints (drier air) reaches to Flagler County  toward Brooksville if not closer toward North Tampa Bay. Temperatures this morning actually got into the low 70Fs in many locations, and last I looked Okeechobee was at 68F with light fog. It has been a LONG time since temperatures have gone this low..since late Spring.


Thus, it will take a while for the atmosphere to be in working order for storm generation today (Central)since the sun rises a bit later and is at a lower angle in the sky. Regardless, with enough destabilization at work   under sunny skies (clouds not a problem like earlier yesterday) and another disturbance approaching..thunderstorms are again a good bet across South Florida and portions of South Central Florida mainly along the east side from Vero Beach south to Ft. Lauderdale or just north of Miami beginning just away from the coast sometime after 2:30pm -3:oopm time frame. Not sure a sea breeze will come into play today, but I suspect a light one can sneak in there.Some of these storms could be rather strong with gusty winds and inherent lightning strikes.


There is a chance that if activity gets started earlier(South) than expected that outflow from these storms will work back away from the coast and generate another round well west of I-95. That same outflow could press north to St. Lucie/Indian River/and Southern Brevard Counties for activity after 4-5pm.


Further north the thunder chance looks a little less certain, but a storm might be able to get going near the Surface boundary in Northern Brevard due to outflow moving north from earlier storms to the SW and South and ramming into the prevalent synoptic scale frontal boundary.  Once again, rains could linger until around 8pm in light fashion along to just off the coast of Central Brevard south to St. Lucie Counties.


Even further north, do not believe that much beyond the Volusia county line the atmosphere will recover enough with ample moisture in depth coincident with the vort max passage to generate anything other than rain showers...but changes are in the works and this could change during the course of the late morning to early afternoon. So far though, not seeing through any guidance for storms to transpire beyond what has already been written above.


FRIDAY: Models again are showing a series of disturbances to cross the central peninsula..even more pronounced than today. Almost makes one wonder if they aren't 24 hours slow. Regardless, tomorrow looks again similar to today..however, as noted yesterday, moisture and the boundary will lift further north as Katia moves away and further North as well. That factor combined with the agreement that high pressure will press in from the east across South Florida in the wake of Maria. Dynamics should then also cross further north but not be as strong, so the fate of Friday is a bit uncertain, especially over South Florida where there will be near zero dynamics other than daytime heating, (which should be sufficient for thunder west of Miami Metro in the Glades).


BEYOND: Saturday and 'Beyond' depends on the pressure  and moisture pattern more closely related to tropical activity, which has been changing rapidly this morning now that overnight model data has become available and will still be filtering in through 3 pm this afternoon. Speaking of the Tropics:


TROPICS: In summary and to cut to the chase, models are trending to agree to disagree this morning. Last night almost all guidance was in near complete and total agreement that Tropical Storm Nate would be doomed for shelling pesos in Mexico; however, the 2AM GFS (which has been quite good all summer)...just shifted gears into reverse. It was first to show that NATE would now lift out of the BOC (Bay of Campeche) once Katia pulls further away...and other more frequently processed data is starting to follow suit.


 Although there is very dry air over the Northern Gulf behind the boundary that is over Central Florida..as noted previously, that boundary is to lift north as Katia moves further north and the ridge builds in across South Florida (Friday). This in turn lifts moisture north as well as merges it with some that has oozed south around the backside of the broad expanse of territory covered by old Lee which is now all in the mid-levels of the atmosphere. Until this can be fully ascertained to be of truth, the future forecast for Florida remains uncertain. We will know with much greater certainty though by 3pm this afternoon. But note that even the shorter term track models are trending the turn northward as opposed to only 3 hours ago prior to this writing.

Most recent 8AM EDT information. Earlier, only 2 tracks took NATE northward. I have also drawn in YELLOW the latest forecast 2AM track of the GFS Model. The official forecast track is shown in WHITE.
Note that the GFS takes NATE as a tropical Storm/Depression into a loop around North and Central Florida as the system begins  to bump heads with high pressure building across the Mid-Atlantic Region. 

NATE is shown in the little white circle , center of image. In lavender is the error of margin in the official forecast track. Two things to notice is that there is abundant heat energy to the north of the system, partially under that dry air by those reds and oranges over the Northern Gulf Coast region. There is energy under that dry air though, as well as in the Caribbean. The CARIBBEAN has not been touched this hurricane season and could easily remain a hot bed for future activity. That area has been shown to get active from time to time now...but guidance has yet to figure how, when, or why.

Elsewhere, there is Maria. This storm is just ekeing out  tropical storm strength and is moving rapidly to the west around 23 mph. I've noted in this image the forecast margin cone of error the Hurricane Center has generated (yellow arrows). Included as well are notes that the greatest shear currently is toward the north side of that cone and the best heat energy is located to the south side of the cone. Forecast tracks of consensus models are very close to the official forecast track, but several other models are taking Maria further south toward the Central Leeward and maybe even northern portions of the Windward Islands. That is what the NAM model has been showing, but then again, the NAM has not been remotely reliable in months. 

Here we see the steering in the white arrowed lines. If Maria remains weak (which looks likely at this time)..the storm could continue west and into the greatest heat energy levels in the water. This heat energy extends into the Caribbean. Thus, this storm ALSO needs to be watched, although all models at this point are taking Maria well north of the windward islands, and then to curve out to sea even further east of the U.S. than Katia has. 

  
Lastly, some model guidance had indicated that a tropical wave would be pushed out ahead of Maria toward the Caribbean and South Florida during the next 72 hours. Whether or not this will even come to fruition is too soon to set in concrete, but if so, would affect the weather outlook for Florida going into latter parts of the weekend.  Also to note, the GFS has been showing every other run or so for another storm, perhaps Ophelia, to form or move into the Caribbean heading toward the last week of September. The last run no longer shows this. Perhaps it was actually picking up on Maria though but has yet to resolve the information as it filters in (?).  


To further complicate matters is that fall is trying very hard to take hold of Florida. Typically, the first cold frontal passage into Central Florida occurs during the mid-last portions of the month, although last year this did not happen in full until September 31st. It was with that event that summer ended immediately overnight with a flick of a switch as a tropical system cut past far South Florida.  That event ended summer for all but SW Florida for another 7 days as easterly flow took over. The GFS of 8pm showed that to occur as soon as next week, but as of 2AM that all abruptly changed. We will need another 2 runs to confirm  Which will it be..End of Summer or Beginning of Fall? 

Faith in Future Forecasts Fruitless - Synechdoche Required

RUC FORECAST FOR EARLY AFTERNOON: At the surface a stationary frontal boundary is aligned near Tampa Bay toward North Brevard County. Aloft, a mid and upper level trough is located in general where the lavender boundary is drawn. The deepest atmospheric moisture is focused along the surface boundary, but ample moisture resides in both directions for showers or thunderstorms today.   Note the large red circle. This is shown as such for a reason which is later discussed.

TODAY: Another day of sketchy forecasting at hand so synecdoche is the word of the day, but a few rules of thumb can likely be applied, so I'll try not to palliate.  As expected could occur, a vorticity max passed across Central Florida overnight producing thunderstorms on the west side into the interior which weakened the further east it progressed. It is possible at least one or two more will follow suite during the course of the next 36-48 hours, but timing is nearly impossible to determine. The latest RUC does forecast a fairly significant impulse to cross Central Florida after noon time through dark though today, so rain chances could elevate during this time frame, hence the good chance of rains in the official forecast per official outlets (I'm assuming). On the otherhand, that energy might go into manifesting as simply cloud cover, especially north of the Beach Line. 


Otherwise, the best instability and chances for thunderstorms will occur along and south of the stationary frontal boundary (wherever it happens to be this afternoon) and where skies are cleared enough for instability to build up. Those storms will move briskly toward the ENE so even locations upstream of their formation could get in on the act, even if mostly cloudy. Skies over South Florida are much more sunny this morning than they are closer to the frontal boundary, but bigger breaks are anticipated central by noon time..not so sure about that either if more energy moves in to early. The best instability is forecast to mount South of the surface front for storm initiation, but steering could transport this activity into the prevalent cloud covered skies just to the north of their initiation.  The surface front will waiver north/south by 50 miles today and tomorrow, but should lift north as Katia progresses north as well. 


In the image above is the mid-level depiction of Hurricane Katia to the east of Florida. As the storm lifts north of the latitude of Central Florida, this should also lift the surface boundary north a bit as well, especially because high pressure is expected to build in from the east across South Florida in Katia's wake. By Friday the boundary should be as far north as I-10.


In consideration of all the factors above, it appears showers or considerably cloudiness could be in store for  North Florida, with showers and a very small thunder chance from near the Flagler/Volusia County line south to North Brevard. Further South toward Central Brevard to Palm Beach County (especially if a sea breeze can form), thunderstorms are more likely. Indian River/St. Lucie/Martin/Palm Beach County toward the coast seem the most likely candidates for this activity after 3pm and beyond until dark at some point. The west coast also has a chance of thunderstorms.     


THURSDAY/SATURDAY: There is great uncertainty in the forecast for the follow up days, but given the expectation (and likelihood) that high pressure will build across South Florida from the Atlantic, this will place South Florida in very weak steering currents with an east coast sea breeze as far north as at least Sebastian Inlet. But, this high pressure will have drier air associated with. Hence, the greatest moisture reside across Central and North Central Florida..at least for a day or two. What happens in the Bay of Campeche in regard to a potentially strengthening tropical system is also a big player. If a storm can get wrapped up in this location, then the moisture source for Florida will be reduced and as such, the rain chances everywhere. So far, it looks like it will be a long time coming before that will occur though. Thus, thunder storm and rain shower chances prevail during this time frame..with that chance working northward toward JAX with time.

LATEST enhanced infrared satellite image and precipitation locations today with notes included on the right margin in orange. Note the cleared skies over South Florida south of the boundary across Central Florida. The blue dot on the east coast is what is left of thunderstorms that formed along a vort max (vorticity maximum, aka - 'disturbance') early this morning and moved across the state. Thunder 'seems' most likely today in the orange areas, but naturally can't possibly be all inclusive. Thunder will not occur in those entire areas either. NOTE the area in the Bay of Campeche and toward the SOUTHEAST SIDE of the Yucatan. This is referred to below in the "Tropical" headlines.    

  
TROPICS: "Much ado about nothing or reason for greater attention in the SW Gulf ?" is the question of the day. Models are split 50/50 on whether this area will become well organized and then threaten the northern Gulf toward the Pensacola/SE Louisiana area...or...never progress into the Gulf at all. Big Difference. So word of the wises, be prepared for surprises...but not anytime soon. This system has a long way to go before becoming 'well organized'..at least as of this morning. Once the area is investigated by the Hurricane Hunters more will be revealed.


For instance, the ECMWF model implies that as Katia moves north, that storm literally drags all of the dynamics and pressure systems associated with remnant Lee along with it. That includes a profound blocking pattern the United States has entered. Blocking patterns tend to hold fast for 4 to 10 days, thus, it is more then questionable that a hurricane in passing would have such an effect on a Northern Hemisphere blocking pattern. But, that is not to say that some variant of that model's hypothesis can't be reached. Either way, all models show that Katia will become one MONSTER of a extratropical storm heading into the North Atlantic ocean in the next 3-7 days. Extratropical Katia could be a major player in many locations in the Northern Hemisphere two weeks down the line.


In regard to the  ECMWF, haven drawn the blocking pattern out, the next assumption is that this willl open the gates for the system in the SW Gulf to emerge and work north and east toward the NE Gulf as a hurricane.


HISTORY OF THE BOC: Historically, the majority of storms that form in this location are pulled northward , but not all of them. In going back and looking at this history, I found that the storms that did so nearly ALL occurred early in the season and not later. This would be because cold frontal boundaries, such as what is now in place...penetrate further into the Deep South the later in the season one progresses with time preventing from working north. That is...all of them but 3 since 1900..and two of them occurred onlly 2 years apart around 1903. The only other one that was actually a hurricane at this time of year was Hurricane Opal...which incidentally followed a Gulf storm just a time prior to another one. Think Lee. The problem with such a due course of action in 2011 is the current location of the frontal boundary and the VERY dry air behind it. This will have to be greatly displaced..and for that to occur, so would the high pressure over Texas have to be displaced, which has been in place since Spring. 


Another observation made this morning is that the models might be giving this system more 'pre-organization' than is realistic. This determination was realized when looking at lightning data and satellite imagery. The most lightning is occurring on the Southeast side of the Yucatan and not in the Bay of Campeche. Thus, the area of low pressure might be much broader than the tight knit depiction of the models.


Below is a two fold image..the lightning as noted above..placed side by side with the track of Opal. Note that Opal FORMED SE of the Yucatan, then crossed it..then took its course toward the Southeast U.S. Other storms that were tracked from the BOC (Bay of Campeche)  toward the U.S.  did not originate there..but rather further east in the Caribbean.

To the left is lightning imagery. To the right is the track of Opal. Note where Opal Formed.

Opal crossed the Yucatán Peninsula while still a tropical depression from September 27 then strengthened northward in the Gulf, becoming the most powerful Category 4 Atlantic hurricane before making a second landfall, October 4, in the Florida Panhandle near Pensacola as a 115-mph (185-km/h) hurricane. Opal devastated the Pensacola/Panhandle area with a 15-ft (5-m) storm surge and travelled up the entire state of Alabama, becoming a tropical storm in Tennessee. Opal also caused heavy damage in the mid-Atlantic states before dissipating. This is the track implied by the ECMWF, except it is not generating in the BOC..and it has the storm taking this course of action in fairly rapid fashion. That means, Katia needs to pull out the blocking pattern in place in the next 96 hours. The ECMWF is not the only model to show this trend as a side note. So this is not to imply the ECMWF solution is not plausible.


The other side note to consider is that 'even if' this system develops in the BOC and lifts northward, it still must contend with upwelling created by Tropical Storm Lee as well as cooler rain waters that drained into the coastal areas off the Mississippi and other tributaries. Thus, to palliate the storm's future course (in this example) perhaps a 'big storm' would be greatly weakened before a true landfall.


The final note on this system...is that other than hurricanes..there was a   Tropical Storm that crossed the Big Bend area of Florida at this time of year ..this seems more likely if anything were to move north.


Outside of the BOC, there is yet another developing system approaching the Leeward Islands. This looks to be our next named storm system. Again, guidance is leading the reader in two directions. Will that system follow the course of Katia..or continue toward the Caribbean?  Again, we are back to square one with what Katia does or with..or what results from..the storms interaction with the remnant blocking pattern of "Lee".


Thus, Future Forecasts are Fruitless not only in regard with Florida's Local Weather, but with regard to the tropics as well.


In closing, the more interesting system if none of these systems impacts the Deep South will be the NEXT one toward the last week of September. By that time, and under the assumption the blocking pattern does not break down early (in which case none of these shorter term systems will directly strike the U.S)..the pattern will or should be in the process of breaking down, but not before the next Atlantic system will already be in the Caribbean. As always, all thoughts are of the writer's own..images provided are actual guidance or real-time information...and future projections, especially beyond 1-2 days are as good as a blind man relying on a blind seeing eye-dog.

Strong/Marginally Severe Wind Gusts in Storms Today

(1)Image shows mid and upper level support for storms . Divergence (purple)well overhead sustains storms, whereas mid-and lower level convergence (red) creates and holds them intact. Note the lack of rains and cloud cover toward Southern Volusia and South. Also to watch for lightning prone storms near the Lake Okeechobee Shadow in Martin/Palm Beach Counties..and Indian River toward Southern Brevard Counties

Images 2 through 4 (below) (1 is above) and  1 above reflects the upper levels. Not too often we see those purple and red lines overlapped in Florida this time of year...now the lower levels, Surface:

(2) Original image shows 0-3km helicity, looks to be caused by wind speed shear (vs. directional shear).
The greatest thermal instability will mount where skies stay clearer longest which is more into Brevard (Central/South)..and Indian River. But synoptic scale wind shear is not quite fully in the southern most area..but could work in after 4-5pm.  Additional highlights: Storms could regenerate further north in Flagler County later as well despite early day cloud cover and nearby showers. Purple Boxes are for the synoptic scale winds (North) and Lake Shadow (South, particularly the one for near MLB to Vero Beach/Sebastian Inlet) .

The above image is mainly showing the best wind profiles will be over Central Florida, but greatest instability will likely mount a bit further south of the best winds ...rather..best for manifesting strong/severe storms. Thus, storms could be active out of those winds as well, along the northern side of the Lake Okeechobee shadow'...assuming there is one. If skies stay clearer long enough, a near neutral sea breeze/vs gradient wind could develop at the coast south of MLB Beach. Either way, that should not make a difference.  Also to watch, is toward Coastal Palm Beach County. 

(3)Latest visible satellite image shows extent of clear sky vs. cloudy.
The leading edge is progressing at a rate it should reach the area around KSC by noon
 ..by which time heating will have begun to increase instability. It is also unsure if the leading edge  will slow down as heating commences. It looks like pure 'outflow' right now..with the true leading edge running back toward Flagler County. Other showers to develop along the SW Coast and work ENE-NE during the late morning hours.

In summary, the same boundary that absorbed Tropical Storm Lee is moving into North Florida. In fact, the temperature across the panhandle was only 60F last hour or two up there. Meanwhile, the boundary extends well into the Mid-Atlantic states and south toward the Bay of Campeche..but might not get much further east in the next few days. The reason being the approach of Hurricane Katia. High pressure surrounding that system could work as a 'blocking mechanism' preventing further east ward progress of the trough. For Florida (other than the panhandle), it could get as Far South as North or Central Brevard. The NoGAPS, latest GFS, and SREF models agree on this scenario through Thursday.  


The Storm Prediction Center has placed Central Florida in a Slight Risk for Severe Thunderstorms today due to winds gusting to in excess of 58mph. There will likely be more fast moving rain showers than thunderstorms...but even heavy rain-showers could generate some gusty winds in the area noted ..which matches closely to the area highlighted in the above images:

(4) SPC FORECAST from www.spc.noaa.gov 

BEYOND TODAY: Expect that the boundary will work toward Central Florida and struggle against approaching Katia and high pressure beginning to build westward across South Florida in the mid-levels. This in turn would create a 'deformation zone' across Central Florida of closely opposing winds at the same level side by side.  Additionally, low pressure development along the far south end of the boundary will generate an area of low pressure in the bay of Campache area which would also slow further eastward progression. Between that area, the deformation zone..and then the remnants of Lee (which is expected to retrograde..or rather, be forced back toward the WNW rather than advancing on to the NE) toward the Ohio Vally.. these three low pressure areas will generate:

A Menage A Trois' of Low Pressure areas:

IMAGE FORECAST FOR THURSDAY: Strength of low in Bay of Campeche highly uncertain but is not likely to impact Florida directly in the next 5 days, if ever. Note that Former Lee, Katia, and this low are loosely 'connected'.  

 THURSDAY: Wednesday might be more of a 'rainy' or showery day..but we'll cross theat bridge tomorrow. On Thursday, the initial surface boundary will begin to wash out. It is possible a low pressure area will form along it either in the Gulf WSW of  Naples or over Central . Either way, it would cross the Central to South Central Peninsula and again create a potential severe weather threat...mainly Southern Volusia toward Ft Pierce on the east coast with general thunder south to Key Largo.


FRIDAY:  Another Sea Breeze day with SW Steering. Thunder again possible South of Titusville to Miami/ Key Largo Area

Un-Named "Lee" Now a Bigger Threat -"The 'Tropical Connection" Remains, Floridaekend"

Area in Blue Should have an Enhanced Tornado Threat as Old Storm Lee Opens Up a Bit..taking a course as shown in Black. The Official Track from the NHS is shown in White just to the left. Either way, makes little Difference. The area in Green will be prone to Heavy Rain and a Tornado Threat Throughout Today. The chance of Tornadoes today looks higher than yesterday as Lee begins to interact with approaching frontal boundary. Note the DRY AIR behind that front. Also note there is a Lagging Trough into the Gulf with active thunderstorms associated with it. This area could approach Florida beginning Wednesday and Be In Place (at play) over Central Florida by Wednesday/Thursday. The heavy rain area shown could shift around and is not meant to be exclusive of areas 50-100 miles to the east or west of that shown

TROPICS/SUB TROPICAL BLEND CAST: Lee was downgraded, but even so, the system now Un-named as a former storm likely poses MORE of a threat than it did while it was named. Reason being two fold: (1) Entering a more mountainous area with deep moisture and interacting with a frontal boundary/plenty of wind/energy dynamics ..the combination makes for a lethal rain making machine.  (2) The system , now having opened up a bit, will continue to do so through the day, and with that, wind fields will become less unidirectional with height. The area in Blue is the best area for a tornado chance today, but even along the Gulf Coast of Alabama, The Florida Panhandle, and Mississippi, the smaller threat will continue.  I would not be surprised to see the risk area extended further to the east and south a bit later today toward the Jax/St. Augustine area..more likely toward Gainesville...very late...but...


FLORIDA ELSEWHERE: Skies have cleared today as opposed to yesterday. As such, very warm today with highs in the 90Fs everywhere. Thunderstorms most likely almost anywhere Central Florida after mid afternoon through mid-evening. There seems to be a potential for 'enhanced' activity from Brevard County and North along and east of I-95 as instability has been building up offshore Brevard since yesterday. In deed, last night an area of thunderstorms developed well off shore the county and persisted for nearly 5-6 hours. This CAPE (instability) has increased even over night.  Thermal profiles for lapse rates (changes in temperature with height in certain levels between two altitudes) aren't all so great. but moisture is high...and sufficient. Do not expect wide spread activity at any one time..but they could line up and move on through inland areas any time after 2-3pm, perhaps a bit earlier further south. The only area that does not look all so great for storms is far South Florida (Dade/Southern Monroe). Most of this activity might only be showers...it is too early in the day to say for sure, but that currently appears to be the more prevalent mode except for near the east coast and interior. 


BEYOND: Tuesday looks similar as the remnant low moves slowly toward the ENE-NE toward the Southern Appalachians and weakens. Moisture and some dynamics might remain for part of the day..but the rains will continue for quite some time as it by then will be interacting fully with the approaching cold frontal boundary.  This moisture/front combination will stretch further north and east toward the NE states. Thus, more rains for the Appalachians of the Deep South and Mid-Atlantic, with run off of creeks, rivers, streams running into the lower land areas. Downstream communities should be on high alert for Flash Flooding.


For Florida, Tuesday looks like a variant of today, with perhaps a tornado threat emerging toward the NW Coast as the lagging boundary approaches the west coast. A tornado watch MIGHT be needed for an area around Brooskville/Cedar Key/Gainesville/ and maybe toward Ocala and west to far NW Volusia and western Flagler County late.  Areas further south might actually dry out just a bit, with a dry slot of air possibly remaining just ahead of that trough..this will have to be re-evaluated on this day. The trend has been for that dry slot to fill in with moisture a bit with time.


WEDNESDAY/THURSDAY: Potentially interesting day for Central Florida. The latest model forecasts are showing CAPE/CIN fields VERY similar to that which appeared when Squall Lines went through Florida in the late winter and early spring. With perhaps a very shallow sea breeze along the east coast of South Central to Central, these storms if this scenario unfolds could be very 'active' in some form. TBD on Wednesday/Thursday.  


BEYOND: The tropical connection continues as of Lee's Demise across the state. The trough so far is not forecast to get beyond Brevard as far as Southern Passage...not for a long time. Recent trends have shown it not to get quite as far south...never barely clearing Volusia before retrograding and weakening by  Friday and through the weekend.  


It is interesting that in the meantime that same boundary will extend the entire way to the Bay of Campeche.


Tropical Development is again anticipated along that boundary anywhere between that location toward the north side of the Yucatan. This activity will likely interact with the decaying boundary for a time..and if it becomes more organized and closes off, then rain chances would go down for a time. However, the trend has been for this 'low' to cross Florida going into the weekend later on down the line, but never getting very far beyond the state. This in turn sets the stage for further development. Bear in mind, that while this is all going on over and near the state and the Gulf, another tropical entity will be on the approach from the western Atlantic and/or the central Caribbean.  Thus, for the rest of the month (or at least the next 3 weeks), watching the Caribbean/Southern and Eastern Gulf/and SW Atlantic for future storm formation.


Katia is now the best looking storm of the season, but it appears will hold very little U.S. threat. Even the outliers like the Navy NOGAPS has trended the system just far enough off the coast than to be nothing more than a marine and near shore/rip-current interest.

"Lee the Loopy Chimney" Lingers - Lingering Effects Could be Long Lasting

General Area of Lightning Indicated By Dots. Circles Show
in General  The Lopsided Configuration of Lee as it entrains (extracts)
dry air from the WNW. Locally today, showers and some thunder most likely as shown over Florida..some sprinkles are possible into sunset further north near the east coast, St John River Valley basin, brief and no impact. Note that the lightning is well out in the Gulf..not near Lee's core. This shows that 1) There is plenty more energy out there to be utilized and 2) There is more to Lee than just the central lowest pressure and immediate wind fields are located, as opposed to well organized, tight-knit tropical system.  Now, see the next image.

See the captions. Lee is Shown by the Red "L". Heat energy in the Gulf in Orange and strongest stacked winds in Black.

Other colored areas show upper level divergence and low level convergence which extend well to the south and east of Lee. That is where the lightning is most located. 

TODAY: Going to try to leave it brief today for the locals. Latest on Lee is that the storm was drifting north at 5 mph or so...and latest radar animations show that Lee is doing that as well as perhaps taken a dogleg to the west. Rain has moved into far Eastern Texas as a result. Although dry air has been getting entrained (pulled in toward) into Lee from Texas, the storm is creating a bit of its own moisture field as it has gained a bit in organization. The very broad wind field over the Gulf is taking in the highest heat energy residing to the south and east of the central area of Lee shown in orange above, of which there might be actually two if one goes up a few thousand feet. Lee seems to be feeding off the heat energy and, like a chimney, is spewing its ashes and soot over the far reaches of the Gulf (divergence aloft), and most of the Northern Gulf Coast communities as fuel keeps being supplied from the Gulf (convergence). The storm can not move at this time far from the source due to high pressure now located to the NE through North of the storm...there is very little shear to inhibit or rather tear down the chimney..so the Chimney Sweeps are in high demand to keep the embers burning. Looks like they are doing a good job too.


Per the latest NHC forecast and model consensus, Lee could linger well into Monday before making a painfully slow move toward the North then eventually NNE-NE as a frontal boundary of unseasonably strong proportions swoops into the Central and Southern Plains states.  All of the models have Lee eventually succumbing to this trough and finally breaking down and being stretched out toward the NE with time. All of them that is, except the NAM...which insists Lee will maintain itself..likely do a loop, then head back toward the breeding grounds.

The North American Model (NAM) has this course of action indicated. Note Katia in the right side of the image. but this time around Thursday or Friday. Again, this is by far an outlier, but nonetheless, indicative
of not only the uncertainties in where Lee will make its even larger impact in days to come, but also those that have been indicated in the long-range through the 3rd week of September. In other words, although this model perhaps can be disregarded it could be used as a tool to read between the lines of what other models are showing as being more definitive. Eventually, something in between all  of them will be the reality.

ANOTHER way of Looking at Lee. The red L near the LA coast is the storms location (very roughly). The heat energy is SOUTH of the low...and divergent upper level wind flow is shown right over the storm's core area. This is helping the storm to spread out..and maintain and even lower its central pressure. In black, I drew in the NAM model track as shown above in the previous image. Disguarding the model in full, but not in part. Overall, it could mean that Lee will be around longer than was originally thought by a good 24 hours at least. Also note the heat energy over the SE Gulf and the western Caribbean. A lingering trough(s) from Lee in this area and/or small tropical waves toward the SE Coast Of Florida are  future contenders for a least some sort of partial tropical development in the next two weeks. Lee will leave a legacy behind in more ways than one. 

In closing with Lee, the main point to realize is that it will likely never be a classic looking tropical system, but regardless, the effects from the storm could be significant from Coastal Lousiana to the Florida Panhandle..extending north to Mississippi, SE Arkanas, East half of Tennessee, W-NW Georgia mountains, and the Appalachians of North Carolina , Virginia, and West Virgina. It still as a frontal boundary to interact with assuming it does head toward the NNE-NE.  That being...remember all of the wind and heat energy shown in the first image over the Gulf which could at least be partially escorted with the system once it lifts north (under the huge and popular assumption that it will). But how much will be left behind? Looks like a lot will be. 


The water further south remains untainted by up-welling of cooler waters underneath.


IN SUMMARY: If there was a lesson to be learned from Irene, NOW is the time to consider the future plans Lee might have in store for the mountainous areas and those downstream of rivers/ogrges in the interior/mountainous/hilly areas of the SE and mid-Atlantic.


LONGER RANGE FOR FLORIDA: Going into this week the forecasts are calling for increasing rain chances as soon as Sunday. So far, that appears to be feasible. Beyond Sunday or Monday (when they might decrease a bit)...it becomes increasingly uncertain since much will be contingent upon the future path of Lee. 


 The GFS has been very consistent though with regard to total rainfall over the next 6 days, with highest totals being near SE Florida in Dade, Broward, and Southern Palm Beach Counties, with another area along the Barrier Islands of Brevard. (Nothing like the rainfall totals that will continue to occur along the Northern Gulf Coast and along the future track of by then Post-Lee ,which will likely be addressed as "Tropical Depression Lee" for quite a while...so might as well get used to it now). 


It is not completely certain if even half of that rainfall over Florida will even be from thunderstorms. Reason being, very warm mid-level air is forecast to wrap around the system..decreasing low level lapse rates...it'll probably be fifty fifty..with most of the rainfall in those locations due to near east coast sea breeze convergence in the noon-sunset time frames. Moisture is never forecast to be far removed from Central Florida and never over far South Florida.  Only the North Half of the state might have a few days of respite from rain chances as we head toward Thursday..but even that might be relatively short lived in the scheme of things once Lee is fully out of the picture and a new page can be turned on the day by day calendar for September.  

For today, not going to say much about Katia. As if Lee weren't enough, the future of this storm is a bit uncertain when it comes to intensity and track. The storm will be moving into a less shearing environment, but also by that time once it gets north of the latitude it will be moving into less favorable ocean energy. This might not have any bearing of the strength of the storm. For now, it is best to focus closer to home, because whatever happens with the Lee-scapades will indirectly have an effect on the future course of Katia in 3-5 days and beyond,

Tropics in a Quid Pro Quo with Sub-Tropics Next 5 Days

Sunrise Thursday Morning Along the 700mb Trough Axis Which Now Lies across South Central Florida this Friday morning.  This means zero rain chances for North Central/NE Florida Through At least  Saturday

Change of Pace Post in Lieu of the Norm. Reason? Negotiations between the System in the Gulf (Depression vs. Sub-Tropical Depression vs Storm vs. Sub-Tropical Storm "Lee")...at hand. Until there is a hand shake or a victor in the arm wrestling match (big difference), if ever, the forecast for all of North Central and most of South Central Florida remains up in the air at best. Only in the next 36-48 can it be deemed feasible to project into the future, especially with even short term model disagreement.


GULF: Based on latest surface observations, winds well removed the surface low circulation of the depression are approaching Tropical Storm Strength. Whether or not the Hurricane Center will thus name the system today (if ever) is unknown. However, I do not see the system ever being anything beyond sub-tropical at this point. Namely because the system developed off of a combination of the persistent thunderstorm activity that had been off SW Florida, combined with a tropical wave in the SW Caribbean, and then enhanced by upper level jet stream wind divergence and mid-level vorticity (the later two are subtropical features). Now, if the jet stream winds that are currently in place (and are by the way what is causing the rain fall now)...were to breakaway..and the system gains a tighter surface circulation and banding around the core...that's a whole new ball game. However, not one model has shown that process to come to fruition. 


Either way, the system is causing high alert along the Louisiana Gulf Coast since some factors are in play either way for POTENTIAL high rainfall totals accumulating..sometimes in a short period of time...mainly anywhere along the immediate coast (and I -10) but also for all of the 'lower-boot' portion of the state.  


Note that there is a difference between the words 'potential' and 'will'.  Because the system is in a  'quid pro quo', which models does one lean toward? The tropical ones or the standard North America Models? How are those models treating this system?  In the short term, most rainfall in Louisiana today appears will be limited to I-10 in direct relation to this system, but other rainfall..maybe heavier, could fall as a result of more non-tropical dynamics associated with what one looks for in thunderstorm activity...a moisture gradient, a mid-level trough,and an unstable atmosphere...non of which are tropical factors (at least, not as far as Tropical Storms are concerned).  

Surface low is in red. Strongest wind is well removed from center (sub-tropical). Red is the mid-level trough axis. This axis extends SE ward toward Lake Okeechobee today. Dry air is north of that trough with high pressure as shown by the blue zig zag//high pressure also exits into the NE Quadrant of Florida today through tomorrow. This analysis is showing 40 kts but latest observations I've seen show only measured just below that. Either way, it could become a named system. The main point is, do not focus on the CENTER of circulation...it holds no bearing as to where the brunt of the system's impacts will be focused. 

    


TODAY/TOMORROW: For Florida, rain chances are limited to South Florida, and even there they could decrease with time. Thus, Florida's weather is also being impacted by this system..for better or for worse..  With time, extended outlooks are calling for worse by Monday...but even that cannot be stated with 100% guarantee (although based on the NAM and GFS it could). Must see what  this system does first...


TROPICS: Outside of the Gulf, there is still Katia.Not writing this system off as one of those "fish storms". There is another hand shake going on further from home...and no one there is eager to agree either...looks more like a stare down for now though.  A trough is developing  east of the U.S..that being, the 700mb trough extending across South Florida this morning extends back to the NE into this area which is being watched for further tropical development, although at this point it looks unlikely...this morning that is.  The same trough is what runs across or near I-10.  It appears Katia will by pass this trough..which leaves the next one to curve the storm away from the U.S.  BUT, that trough might get hung up at its southern end in the Southeast States. Why? Because of what is going on in the Gulf...back to square one. It sounds confusing if one doesn't have the mental  picture and the process envisioned:

This is a  GFS forecast for early Monday. Note how broad the gulf system is..and is never 'cut off' and on its own. Most impacts will be to the east of the center of this mid-level low . If this goes on Katia will be steered away as mid next week approaches

From  the looks of future development of Katia,  it is now in a shearing environment, but that looks to end in the next day after which point the storm could form into a monster. From that point, it could take on a life of its own and all models are out the window.


Thus, a lot of what happens in the next 1-4 days could have long lasting and major impacts to the weather anywhere east of the Mississippi 7-10 days down the line in regard to the depression or eventual storm. For now, watch out if it begins to fade off toward the SSW..this could have a big impact on the steering of Katia way down the line later next week.


Big surf looks like a given for the SE U.S. Coast come this time next week though...


Here's a case in point. The GFS has been trending for Katia to become a major hurricane poised toward Florida, but then being caught up in yet the next trough . So far, though, the system is forecast by the main models to eventually steer clear of the U.S.  I'm seeing only two scenarios..either it stays further south and runs toward the South Half Of Florida (if something toward the Navy model occurs, which so far does not quite seem to be the case) or the straits, or it curves and does not impact anyone directly. (which has been the preferred option by the pros including the NHC I believe).


One other note: Not to be short-changed, watch out anywhere up and down the Appalachians into Tennessee and North Carolina. The day too may come for flooding rains toward the second week of September if the GFS and ECMWF verify.      

Word of the Storm Season - "Hype"

Broad scale rotation under a developing thunderstorm on Tuesday. This storm is being viewed near the Beach from the SSE in Cape Canaveral looking toward the North Atlantic Ave / A1A Triangle Area . The white colored clouds near the top were moving from left to right, while the dark core contained recurrently developing updrafts tags which kept appearing from behind the taller tree to the right in this image 

Believe that a sort of Shear Funnel Cloud (at a minimum) formed yesterday not as a result of the area pictured above, but of one that followed this one as it moved off to the ENE. The second area of similar nature developed under outflow from this area as it moved away..and internal mechanisms drove wind speed shear (but light)..in such a way to form a substantial but very brief funnel cloud. As I stood out there, the sound took on that of a rushing ocean overhead..as it then moved toward the North and toward this formation above. Officially, the event was not recognized as a funnel cloud in print. Immediately pictured below (from video) is what appeared from over my head (to the left of the palm tree)...moments earlier, it sounded like the sea shore was immediately upon myself.  It was just as much what was HEARD as it was that which was SEEN. 

 

TODAY: Not a whole lot to say for today. The same theme as the past two days applies. That being, rain can occur wherever extensive cloud cover does not take over, or where cloud breaks can occur prior to 5pm.


That being said, the only impetus to create showers/storms is a slightly unstable atmosphere and a developing but light east coast sea breeze. Where the bigger cloud breaks occur, which currently is far SE Florida and near I-4, thunderstorms can form, although they could form elsewhere, time permitting for cloud breaks. Otherwise, the 700mb trough axis sank a bit south overnight (it was over Central yesterday). Models earlier indicated it would lift back to central, but so far that has yet to be seen.

The red line is the forecast position on the RUC earlier for the trough axis. However, the trend I believe is for it to become more ill defined than previously thought. Suspect it might break off into the Gulf off the SW Florida coast, with the remaining boundary becoming more inactive with time. Note the Jet Circulation. Dry air encompasses that region in Northern Gulf. These two components have been presented for potentially a reason working into the weekend and next week (see "Tropics"). 

Divergence is occurring further from shore today, having less enhancing effect on storm development today. Additionally, the winds are spreading mid-high level clouds across the South Half of the State. Thunder could occur most anywhere, but most likely will occur inland from the sea breeze and north of the Beach Line. Other areas of thunder could occur over far SE Florida. In between, renegade showers can form most any time, mostly near the 700mb trough axis, although there to...cloudiness might be the rule. Best spot for thunder in orange.

BEYOND: It looks like rain chances will decrease going into the Weekend as 'something' attempts to get more organized in the Gulf of Mexico...with little in triggering mechanisms and no focal points, the most preferred area by Friday should be along the Central interior and west toward much of South Florida, mainly west side.


TROPICS: What tangled webs do models foretell?   Plenty.  What will likely be Hurricane Katia (if not already) is forecast by long range models to miss the U.S. because of a trough of low pressure which is forecast to be in place just east of the east coast extending into Florida by the time the storm arrives. However, the storm has to curve more toward the NW with time during the next 3 days or so first....


Thus, we'll cross that bridge if need be when the time arrives. So far, it appears the biggest impact would be to Bermuda, but that to can change. 


What is of greater interest is what can be happening in the Gulf in the meantime.  Been preaching to deaf ears it seems about this one for some time now..perhaps it will finally be Reckoning Day . Hype this.


The GFS for 3 consecutive runs has developed a hearty low pressure area anywhere between the SW Gulf toward the Texas Coast all the way over toward Louisiana. At this time, if that is to occur, it would be because of the mid-level cut off 700mb trough remnant, combining with that persistent area of reoccurring thunderstorms off the Florida SW Coast (pictured above), combined with another area of low pressure in the western Carribean.  Further enhanced by the jet circulation is some form as shown in the previous image above.


If a low does develop per the GFS it would be south of Louisiana in general. It could hang out in that location for quite some time until it has reason to move. Do not believe it will have much of an impact anywhere west of the  Mississippi River, although coastal showers and thunder is not completely to be ruled out in the interim as far as Texas.  For three runs, the GFS has this organized area of low pressure meander until the next continental trough comes along to the north..at which point the low is forced NE ward into Florida somewhere along the NW coast.  Hype this.


If this were to occur, we'd be looking at either a Sub-Tropical Storm Lee..or perhaps a Neutercane Named "Lee"...which per chance is a name that can be used for both males and females. (the term Neutercane was discontinued for the very reason that it sounded sexist, as if Hurricanes have a gender anyway.) That argument would hold water if we:
  A) called them Her-icanes, Sheicanes, He-icanes, or Himicanes as the list is run down each season.; or  B) gave them non-sexist names to begin with like like Giggles, Scratchy, Boomer, or Pumpkin. Hype this.


At this point, it should be sub tropical if the GFS is to be believed, because: 1) it would form off a remnant low pressure trough from the mid-level 2) It could also form as a hybrid off a mesoscale convective complex like that off SW Florida, or 3) it could form along that deformation zone shown in that image above the immediate one above; and lastly 4) it would have jet stream level winds running through it...a big no no for the purest Hurricane at heart. Hype this.

 .

    

Seat of The Pants Forecasts and Weather Anomalies Rule 2011. Is More on the Way?

No Doubt, Another Fly By The Seat Of Your Pants Forecast Day. All in all
the synoptic scale pattern has not changed much from yesterday. There is more moisture available and it is deeper further north toward I-10 on the east Side.  Again, high clouds from storms over the Gulf as seen in the radar overlay above are spreading anvils (high clouds) across all of the South half of the state. South Florida seems to be really socked in with some other sorts of clouds on visible satellite imagery as well...yet even term models reflect good thunderstorm and rain shower coverage in this area later today 

(Refer to "What's Up?" further down to jump to the subject topic of today's post).

WHO MESSED WITH SUMMER? : Another picture book day to describe what is a non-typical summer day (one of many already and more to come through mid-September for the most part). We have definitely entered a period both pre- and post-Irene of mid-level troughs and tropical systems, surface boundaries and periods of the jet stream near by. In a sense, this is still the wet season but it is not the typical....:


 "high pressure Atlantic ridge axis across Florida with sunny mornings and light winds aloft followed by sea breeze convergence somewhere over the interior late in the day synoptic scale set up we normally have this time of year." 


 It appears that all ended when the pattern that evoked Irene to takes its run up I-95 (nearly) was the end of it.


 WHAT'S UP? It's as if summer packed its bags and went on vacation to Canada in tow (in some places like Florida even though it is still warm here)...leaving behind only the necessary items to keep the house in working order. That being, to keep the rain chances in check (but created by different mechanisms other that sea breeze convergence) such as troughs at different levels (that belong much further north ) and tropical like activity. The Old Salt of the Sea has come in to tend to matters while summer is sabbatical,  and he's messing around with the neat and tidy order that was once in place.  Actually, for this time of year it is not all that unusual, but I'd expect to find it more like in about two weeks from now. Will summer return ever for 2011? Yes, but modified. 


One of those self-improvement camps I guess was in order, since very little of this summer has ever been typical. This was long ago noted to be possible with the high pressure over Texas. This all began a LONG time ago, before the implications could be seen, felt, or experienced.  What was the first sign? The blizzard by Chicago, the Super Outbreak Part II Tornado Onslaught in the Deep South, or the one in North Carolina?  The heat wave in Texas that morphed, spread, shrankn and shifted around the southern tier of states? The lack of tornadoes west of I-35 in tornado alley this year? The supercell thunderstorms and tornadoes in North Central California while tornado alley was in a tornado drought? The deep snow in the Sierras in July?..Must have left a lot out. 


 Point is...expect more odd ball, out there anomalies are yet to come beyond the latest, the Irene event in Vermont (albeit created by rain..but it was odd ball nonetheless). 


TODAY: Same factors to leave things up for grabs in regard to rain chances. Best chance is where the least cloud cover exists, which is near and north of I-4. This is shown below. But other areas could see rains as well. In short, the normal summer rules do not apply today. Looking for the same factors as yesterday, but with slower steering and perhaps a sea-like breeze along the coast. There is a mid-level trough in place across I-10 or just south of there, and this will sink to South Florida going into Friday, but never completely washes out ..if not retrogrades a bit going into next week. It might even disappear off the charts for a while, but it will be back. 

Watching the areas closest to the mid level trough in black. SE Florida could still have many showers and storms with an east coast sea breeze, especially if the clouds can break up a bit...these are not drawn in...

TOMORROW/WEDNESDAY: The mid-level trough axis will sink a bit further south, so another day or two of tricks in the forecast are in store as it looks now. But, rain chances will be decreasing from North to South with time to some degree as more of an easterly flow moves in behind that boundary.  For a short time. 


Note: this boundary is also working into the SW Gulf where storm development is expected there as well. Whether it will be considered 'fully tropical' is yet to be determined..but the signal is clear. A low pressure area is in the making from the western Caribbean into the SW Gulf and north around the Texas to Louisiana Coastal areas.

By Saturday, the 700mb trough pictured in the previous images is located just north of the Florida Straits. Rain chances continue at their highest in this location and northward along the west side of the state for a day or two. Note the huge low pressure circulation in the mid-levels in the Gulf. A surface low could form here eventually...and is likely. But, if history repeats itself as it often does..it could take almost a week or more to do so.

What is shown above is the broad low pressure circulation in the Gulf. The GFS eventually closes off one or even two surface lows. So far, they do not look completely organized, but would not be surprised if a tropical depression or even a storm is decided to be located there by the end of the first week of September.  

GFS for September 5th. Note that huge storm to the right. That is the GFS forecast for Major Hurricane Katina. A lot at this point in time is contingent upon whether Katina will even take this track in the first place. Per the GFS, the low in the Gulf gets caught up in the same trough shown in red along the eastern sea board..and piggy backs behind Katina...across Florida.

 

TROPICS: Tropical Storm Katina was realized early this morning. Model guidance is in close agreement through days 3-5. The storm is taking the path of least resistance where sheer is the weakest. The warmest waters are south of the storm now, but it will be entering warmer waters in about 3 days.  At this point, the best thing to watch will be its track during this time frame. ..especially near the end of the period. ..as it approaches the Lesser Antilles. At time, it is not expected to impact those islands..but to begin a stair step curve to north of Puerto Rico with time. This is not set in stone...The image above shows where the storm will eventually end up on the 5th of September. Looks big...don't want to be messing with that one..so keep your fingers crossed.  But......

Satellite and SAL (Saharan Air Layer) composite...the drier air around  the storm is to decrease around day 3 or 4 as the storm enters warmer waters which are now just south of the forecast tracks shown.

 
...BUT...look what the GFS brings into the picture further on down the line...for one week later.


This system is forecast to move west and under the high pressure that would build in behind the passage of Katia...at this point in time..both the future track and especially this depiction are purely fictional...but it shows what can get the weather office's dander up in arms while the rest of the world is kicking back in the easy chair on weekday nights downing brews and eating Bon Bons.