Thanksgiving Weekend Round One- Showers Today

IMAGE: Mid Morning surface temperatures are shown. Note the 70F degree isotherm. It is along and south of that line, in general, that the best chance of showers should exist today. The area in light blue is where measurable rainfall totals appears to be  possible, but not solely inclusive. However, even those chances look pretty slim, with coverage likely being restricted to a few locations (again, if any) by early afternoon through dusk.

TODAY: Surface high pressure just off/near the coast of Georgia/South Carolina and in the mid-levels almost directly over the state of Florida today is making for weak steering currents with low to mid- topped showers  moving from the east to ESE toward the west to WNW. All model guidance this hour is showing for some pretty good rainfall across the Southern Half of the state..or rather..some moderate rainfall in showers  with truly measurable amounts without having to bat an eyelash in doubt. 


However, that has been the case in the short term models for the past few days with not nearly the coverage depicted..nor where it was expected. Given the trends of morning radar/satellite loops I suspect they are again over-playing today's wet spots so taking the broad brush approach as shown in the above image for favorable coverage areas. Outside of those rain chances, the winds have noticeably dropped off, which sure is nice change.


 Net result will be a warmer day along the east coast and likely interior outside of the clouded over areas, with highs in the low 80Fs and possibly some mid-80Fs interior areas South 1/2 of state. Low 80Fs north.


TONIGHT/TUESDAY/EARLY WEDNESDAY: Very light wind and rain chances ending as the sun approaches the west horizon with nightfall. Near calm wind tonight with a shallow low level inversion under mostly clear skies should be able to set up for respectable 'fog spots' almost anywhere with good radiational cooling , especially the north half of the state.


Tuesday looks to be a dry one with comfortable temperatures running again close to those of today, but with warmer temps running the across the entire state by afternoon. Light winds not worth mention.


Wednesday again has a chance of early morning fog/mist, especially South. This was noted as a possibility nearly 5 days ago if not more and continues to be the case. Very cool morning for east coasters with a west wind (very light). This will mean "no sea breeze, land breeze instead" and thus no warm ocean water air being pushed ashore. Lows in the lower-mid 60Fs as opposed to the lower 70Fs that were felt along the east coast of Brevard and South this morning. Lower 60Fs seems to be the prevalent mode in the morning (widespread), but warming into the mid-80Fs over a broad expanse as a cold front will be moving across the Panhandle early in the day with some showers/thunder possible there. There is a front on the approach, and temperatures Wednesday morning might actually be cooler AHEAD of the front than behind the front (in the mornings).


THANKSGIVING EVE/THANKSGIVING: Cold front timing of course is always a player this time of year in the wind/rain/temperature fields (i.e., weather).  Like the previous front, this one appears to go through mainly dry for  Central and maybe even North Central this go around..and mainly overnight with some clouds. Front will be moving across North Central  after midnight toward sunrise and should clear the CDL (Central Dividing Line) close to sunrise, followed by NW winds gradually veering to north to NNE by day's end. The boundary could be playing through the South Half of the state most of Thanksgiving Day, with a better chance of showers along a line from Vero Beach - Sarasota and south. Comfortable temperatures even behind the front but becoming breezy toward the east side by mid-late afternoon as a wind surge moves in. Chances are this will be accompanied by cloud cover. All in all, averaged over the years, this looks to be a very "average Thanksgiving" for most of the state other than the south half. Previous Thanksgivings have varied to very very warm to Severe Weather, but mostly are uneventful.   


This front looks like it will have very little impact on the temperature fields worth mention. Temperatures return to those experienced the past few days (with today - Wednesday being warmer), with similar wind as well, stronger for a day or two from the NE-ENE-E after frontal passage.


EXTENDED THANKSGIVING WEEKEND: Looks similar to the  previous post of a few days ago: Another front will break the "one front a week rule" of the past month or so, with an arrival at the End of Thanksgiving Day weekend or roughly 4 days later. It is possible this low pressure system/front could entrain moisture from the tropical Pacific, with a steadfast surface to mid-level low to develop over the area around North Georgia with time. Timing would place the boundary through late Sunday..and it's not pretty.


As noted previously, this second evil twin front could be an introduction to the formal onset of Florida Winter almost right on cue with December 1 except it would be around the 28th of November. Overnight lows do not look terribly cold; it is the amount of dry air and very cool afternoon highs that will be the bigger impact if all goes according to "Plan". 


The front also appears to have a better potential to be a 'wet' one...with possibly preliminary rain/showers impacts as well as opposed to only with the front proper.  All in all, experience says that once a pattern is broken this time of year it could be a longer duration break from previous experiences in the same period/time frame. Thus, overnight low and day time highs might never fully recover to those we've had the past week or so.  This boundary could also lower the water temperatures along the near shore Atlantic which would mean that the next time we have onshore winds they will be cooler from previous periods of long duration easterlies. 


Still too early at this stage of the game to set the extended  down in concrete...  all could change in a flash.  At least we have a head's up, not to be worse for wear.

Dis-solving/De-Volving Frontal Boundary Making for Low Confidence Forecast

Radar Shortly after sunrise shows band of convection with lightning/thunder involved across North Central/West Central along a pre-frontal trough, with the actual cold front lagging by a good 3-6 hours.

CURRENTLY AT POSTING TIME 845AM EST: Low clouds/ceilings and some fog exist across the peninsula from along the leading edge of the pre-frontal trough (noted by the rain/thunder on radar above) and South, with the densest fog being officially report near West Palm, Winter Haven, and Ft. Myers. Elsewhere, skies vary from cloudy to nearly clear. ..with some sprinkles near the Keys and showers off shore South and South Central along the west edge of the Gulf Stream and/or the western periphery of high pressure pushing offshore the East Coast in the lower portions of the mid-levels.


Yesterday, a record high was recorded at JAX, and a record warm morning  low temperature was measured at Melbourne (72F). 


TODAY: Low confidence forecast in the rain department today. Based on latest RUC and very early morning GFS/NAM, what is left of the pre-frontal trough will press toward a North Brevard to Sarasota line by noon or shortly there-after. The actual cold front remains several hours behind though. During the course of the later morning to early-mid afternoon expect that some diurnal effects could allow a bit of a 'catch up game' to commence between those two features, although for the most part the boundary denoting the prefrontal trough never really clears much further south than the CDL (Central Dividing Line) tilted toward Sarastoa to Titusville/Sebastian (somewhere in there).


 Cloud cover will also be tricky since the rain/thunder forecast (particularly from Central portions) will be at least partially reliant on 'lack thereof clouds' to destabilize the atmosphere. Additionally, during the course of the day Deep Layer Shear (through all portions of the atmosphere) and increasingly weaker lapse rates (temperatures not decreasing as much with height) will add to the uncertainty on how unstable the atmosphere will become through a deep enough layer to generate thunder. 


As can be seen on the earliest available visible satellite image, high clouds could impact Central late morning through afternoon. Whether those will erode and/or press off more toward the NE is uncertain, but so far that does not look to be the case.

In this satellite presentation, the band of clouds/rain can be seen across the North Central Peninsula in relation to the cold front. It does not appear that they will be eroding, and could begin to blanket Central Florida as far South as Melbourne by late morning, however, some of what is near East Central in this image is actually only  low clouds / fog, which will dissipate by mid-morning.

     Time-phasing just exactly 'when the front will be where' becomes more difficult when looking through various levels of the atmosphere. High pressure is also building ENE from the SW Gulf, so the upper level winds could become WNW-NW prior to the surface wind shift related to the front proper. 


When all is said and done, and to keep it at a less confusing level for reading purposes, Dead Central will be within the confounds of the frontal boundary at some level or another (surface to 5000 ft) from where the pre-frontal boundary is now located and south toward a Vero-Charlotte (west coast) until late afternoon. South Florida might never see a solid SW wind ahead of the front, but could still see showers and maybe even some thunder either way though.

EARLY MORNING FIRST BEST "WILD  GUESS" for rain and thunder chances. Do not expect a broad coverage at any one time, with rains confined to either Central (especially near the east side) and South of Lake Okeechobee after 1pm and beyond. Dashed orange indicates where thunder could occur, but as noted above, at this time of day (9AM) it's as clear as Mississippi Mud just exactly where thunder is most likely to occur.

IN SUMMARY FOR TODAY: I'd anticipate that it will become much more clear where thunder/showers could or will occur by 11AM -1PM once diurnal heating has commenced and the cloud pattern trend becomes apparent. Latest RUC/NAM and the GFS (which has been consistent) that there will be a frontal 'hang-up of sorts" during the diurnal cycle along a tilted CDL as noted previously (above). Showers/thunder could occur here near that line from just after noon time toward 4pm concurrent with other showers further south of Lake Okeechobee (mostly over the Everglades)..SW of Lake Okeechobee.  Chances are, that once the sun gets within about 30 degrees of the horizon there will be a rapid transition with the frontal boundary re-emerging on paper over Southern Dade county (around 7pm)..after which point it progresses toward Central Cuba by Friday afternoon.


LATER TODAY/TONIGHT: Rain chances end for those locations currently receiving rain now by late morning, with the better chance toward Southern Volusia to Southern Tampa Bay and south across the Space Coast / Orlando. (as noted)...as well as South Florida mainly near the East Coast and SW of Lake Okeechobee from 1pm and beyond.


Winds today will be mostly SW and become nearly west behind the decaying prefrontal trough. Frontal passage will be non-eventful with a wind shift to WNW eventually NW and then North, working down the coast from Central to South Florida between 6pm to mid-evening, and increase in speed as winds become Northerly and eventually NNE-NE overnight to early morning in the 20-30mph range, especially near the coast.


TEMPERATURES: As of this morning, temperatures behind the front are in the mid-upper 50Fs in the western Panhandle, and even still in the 60Fs behind the front after immediate passage. 70Fs remain toward JAX and South. Post frontal temperatures late tonight through Friday will resolve with lows mainly in the low-mid 60Fs from Ormond and South, and rising toward the mid-upper 60Fs Space Coast and low 70Fs Treasure Coast and south. Afternoon highs ranging from the 60Fs NE Florida toward 70F mid-lower Space Coast and above Treasure and south. Ongoing NE-ENE winds of 12-25mph off the ocean (the quick recovery in onshore winds) will preclude significant low level atmospheric drying, so this day could also be accompanied by scattered to broken stratocumulus clouds and rain showers/sprinkles (mainly South Central/South Florida) providing for further reason to temper down afternoon highs as well as preventing overnight lows Friday night from falling little if at all South of DAB after sunset Friday night.


WEEKEND: GFS continues with the trend of high pressure rolling quickly from Western Kansas eastward to Arkansas/Tennessee and off the Carolinas by Later Saturday. Winds become Easterly and gradually decrease on Saturday afternnon . Eventually, winds above the deck become almost ESE and rotate a portion of the mid-level front back north toward South Central. Rain showers and continued cloud cover at times during this transition (especially Sunday) could result in sprinkles and measurable but small amounts over South Florida and Coastal South Central, with lesser amounts to barely a trace north to JAX...although sprinkles could occur toward JAX as early as Later Friday as well.


MONDAY: By Monday it all becomes a moot point as winds decrease and high pressure in the mid levels builds directly over the state ahead of the next large upper level trough over the Western US. Still though, there could be some annoying Stratocu almost anywhere through Monday/Tuesday, with a re-emergence of the early morning/overnight low cloud/fog issue in extended forecasts under the high pressure since low level moisture remains, especially Tuesday/Wednesday.


WEDNESDAY/THANKSGIVING: As noted in previous posts, we've been essentially on a "one front per week" schedule/cycle over the past month, and the next front enters the picture unfalteringly (unfaultering?) so per guidelines. This has been on the platter for several model runs, but just exactly what transformation /weather conditions this front will entail is only slowly coming to light. The trend has been, or appears to be heading toward, a cloudy and possibly more wet Thanksgiving and into the weekend..with comfortable temperatures: aka - the round the clock 70Fs, with some lower 80Fs scattered asunder.


However, on the other hand, the GFS is screaming "PATTERN CHANGE" as well. This will be a change in the hemispheric (northern) realm more than likely, with the next front forecast to come in quickly only 4 days later as opposed to 7. This will be very close to the last day of the month, eerily on the cusp of calendar/meteorological winter, December 1. Could be a big drying trend in the future with another overall lowering in morning lows and afternoon highs the majority of the time, or rather, toward norms. In short, winter could be knocking on our chamber doors...Get Back, Jack!...(need we say, frost?).  

Near Record High Temperatures, Small Shower Chance Late Day/Evening

TODAY'S HIGHLIGHTS features surface to mid-level ridge across South Central which will drop only slightly south during the day. Satellite image at sunrise reveals areas of either very low ceilings or fog. Deepest moisture resides over the East Central Gulf and along a cold front approaching the Panhandle later tonight (where some thunder could occur). 

RECAP: Showers formed yesterday in the proscribed zone in the prior two day's of posts from Southern Polk County and across most all of Central Osceola County toward dark, eventually dying off toward 10pm as they reached the Titusville area. There has again been some fog reports, but not with the greater coverage of Monday morning. Lower clouds seemed to be the more prevalent mode, as temperatures in many areas statewide were mostly in the low-upper 70Fs, warmest along the SE Coast near the warmer Gulf Stream waters from West Palm and South where winds remained off the Atlantic overnight.


TODAY: Not all the much different from yesterday, but there are some minor changes, mostly in the strengthening S-SSW-SW gradient low level wind flow north of the ridge axis shown above as the frontal boundary and supporting mid-level trough approaches from the Deep South region, positively tilted toward the Ohio Valley. This can best be seen at the 2000 ft level, as forcing and wind fields at the surface are weak and less discernible for presentation purposes.

Latest RUC roughly shows the front to be located at 2000 ft. above ground as shown, with ridging across South and South Central Florida along the high pressure ridge axis emanating from east of Bermuda. Both of those ridges will drop generally another 50 miles south during the day, and place Central Florida from generally 20 miles south of the CDL (Central Diving Line) and north in stronger SW-WSW flow from 2000 ft and up by mid-late afternoon.   Recall from the first image, deeper (but not tremendous) moisture is over the East Central Gulf. This moisture will circulate east and north during the day into those locations along and north of the ridge axis, or roughly from  Melbourne Beach to Tampa Bay and north by sunset. Dry air is being advected into South Florida north of Cuba. 

 TODAY: Frontal boundary to enter the Panhandle by tonight. Winds today over North Central and North Florida from SW-WSW becoming more southerly toward South Central and SE South Florida.


The RUC model indicates the best moisture will rotate in later this afternoon toward Brooksville and exit the east side of the state very close to a track following along I-4, where showers could occur. 


On the other hand, the latest NAM is depicting a scenario similar to what occurred late yesterday/last night, only about 20 miles further south and east. This would place the area of Central Osceola County again in the better rain chance as well as the area very close to 528/Port Canaveral/Cocoa Beach/as far south as Melbourne Beach for a rain chance between 6pm -10pm as opposed to the more northern area of interest of the RUC. Either one is game, but at this time resting on the NAM which has not been the favored model for quite some time (since summer). However, it seems to have been doing fairly well during the first 18 hour time frame and always one or two steps ahead of the RUC, and did well yesterday.  


These showers could actually emanate/result from a weak Lake Okeechobee Shadow affect (there was one visible yesterday), which would provide the moisture convergence necessary to result in some lower topped showers. I saw one lightning strike on Lightning Tracker last night toward Southern Polk County, but for now will leave it out (which could change) for today. CAPE (instability) appears that it will be even stronger today, but lapse rates on the other hand look weaker which will 'negate CAPE'.   See first image above for those areas highlighted in lime green.


TEMPERATURES: Otherwise, outside of the rain chance it could be pleasantly warm today under partly cloudy skies. Highs in the mid-80Fs interior South and Central Florida. With clouds starting the day in many locations, some records could be toyed with toward the west side of Lake Okeechobee running along a diagonal toward Interior Volusia under to condition that there is good spatial separation in the clouds during the peak sun angle hours. The coolest areas today will be downwind of any water body which would mean the areas east of US1, to the north and northeast of larger inland lakes, and along the north shores of Lake Okeechobee.


TONIGHT: Frontal boundary will be working across the Panhandle. Best chance for some repeat fog conditions appears to be further south tonight, essentially almost anywhere near and south of Lake Okeechobee. Surface winds and especially just above the ground tonight should be too strong for fog north of The Lake  as the frontal boundary approaches and the pressure gradient between that feature and high pressure over South Florida remains firmly in place over that region, resulting in much lighter winds at all levels over South Florida.


THURSDAY: Front will be working from NNW-SSE during the day. Latest guidance generally agrees that the front will work past Gainesville toward I-4 between 11AM -1pm, and will be accompanied by a good 6 hour window of most cloudy/cloudy skies and perhaps some sprinkles. Instability will be able to build further south of the I-4 during the afternoon further from the cloud cover,  with winds from the SW-WSW resulting in highs in the lower to maybe mid-80Fs depending on how soon the leading edge of cloud cover moves in. Although there is a chance of less than measurable rain along the front, the better chance for measurable rain will be toward the East Side of the state South of I-4 to north of Sebastian Inlet from 2-8pm. Frontal passage across the CDL (Central Dividing Line) should be close to 6-7pm time frame. The front then washes out at the surface south of the Beachline Zone and continues south at  the 925mb level (around 2000 ft above ground) through South Florida, finally becoming fully absorbed at all levels near Dade County. Rain showers continue mainly down the east coast on and behind the boundary with a continued chance all day Friday, mainly Southern Portions of Palm Beach County , Broward, and Northern Dade.  High pressure will quickly work east behind the front tomorrow through Friday from western Kansas through Arkansas and finally the Carolinas on Saturday. Pressure gradient wind behind the front as this high pressure rapidly builds east increases over the Atlantic and works in along the Florida east coast overnight Thursday night/early Friday and works down the coast Friday afternoon into Saturday. NE-ENE winds initially in the 20-30mph range will decrease most locations by mid-day Friday but remain in the 15-28mph (esp. South Florida) all day Friday, gradually weakening on Saturday.


TEMPERATURES BEHIND THE FRONT : Not a big cold down, with the most notable temperature impacts interior North Central toward Ocala and North, with other areas feeling lower 60Fs interior to near 65F Coastal East Central from the Port and South for morning coffee. South Florida will not feel much of a change at all. The bigger impact is to the afternoon high temperatures which have been running well above climatology   the past few days, which will return to near or just below normal, but remain comfortable  enough to preclude breaking out winter wear, or for the most part, even fall wear.


BEYOND: GFS continues to imply that as the flow becomes more easterly to ESE just above the deck that some remnant energy from the front will circulate back north toward East Central late Saturday or early Sunday with rain showers resulting, mainly low topped sprinkles with accumulations possible. It is also consistent, however, with ending any rain chance by day break Monday...from which point on, the weather appears will be quite bland with no impacts other than a return to inland fog or low clouds by Tuesday and Wednesday mornings  as winds weaken.


THANKSGIVING: Outlooks for Thanksgiving a Bleak Friday will be included commencing Thursday.   

Chance of Showers and Possible Thunder Mid-Afternoon Toward Sunset

Pre-Sunrise Radar image showers some light to moderate showers working from south to north along the east coast. The area outlined in white toward the east side is a very general depicture of those areas which received measurable rainfall from late yesterday through early today. The red "x" is the center of what appeared to be a weak vort max or nearly a microscale convective vortex which was apparent when radar was animated. This area moved north and into the low level ridge axis at which point the more appreciable rainfall abated.

RECAP: Overall, not much change from yesterday's reasoning. Fog was reported in many areas across interior South Central to west central and over much of North Florida this morning. Rainshowers worked up the coast from as far south as Southern Palm Beach County early last evening but also occurred concurrently toward East Brevard and Indian River. Overnight, what appeared to be a weak low level vort max evolving from the activity over Palm Beach County organized as it worked up the coast, especially after 4AM across Eastern Brevard County but spreading the wealth into Osceola and Orange Counties as well. Heaviest rainfall reported per CoCoRAHS volunteers was from Eastern Indian River County to Cape Canaveral (where the highest total of .57" was reported, albeit this report was a little conservative and could have been a bit higher).  It appears from my perspective only from what I've read that this rain was 'convectively' driven but resided a bit elevated (not solely surface based) above a shallow inversion around 500-800 ft), and was limited in vertical extent due to drier air aloft in the absence of greater instability and/or external forces or boundaries. Fog quickly formed in some locations toward Ft Pierce "post rains", with the now fully saturated low level atmosphere and ground from earlier rains still present under neath the shallow inversion as the vort max lifted north (and likely, some subsidence behind it as well). By the time the area of showers lifted north the sun was up and daytime, diurnal mechanisms were already in play precluding fog over most of Brevard. DAB also had some fog well north of the approaching vort max and under the low level inversion. ..in all cases, the inversion was very shallow and not impressively strong.


TODAY: Per model guidance sounding forecasts, the low level inversion present at the time of this writing should be breaking up between 10:45AM - 12:15PM. Partly cloudy skies as cloud types transform to a mix of stratocu and cumulus with sufficient breaks , especially across South Florida for highs to reach the lower/mid 80Fs in a few locations. Expecting more clouds Central and North to refrain above the lower 80Fs to near 80F at the coast south of Cape Canaveral where a slight on-shore or side-shore wind closer to the water will tone highs down a few unsubstantial degrees.  Current LDIS plots, latest RUC, and morning NAM indicate present and future convective instability to be in place by 2pm this after from just north of I-4 to all of South Florida. Surface and low level ridge will be located across South Central with the mid-level ridge not far from the same position. The only differences with the runs is 1) RUC has mostly early shower activity in the area shown (below), which would preclude any thunder. On the other hand 2) NAM/GFS are holding off on any rain until after 2:30pm (at least) if not later, which at this point I'm more likely to favor. In other words, the RUC which showed nothing earlier might be jumping the gun. With that said, better heating over South Florida to transport instability northward toward   I-4. With forecast CAPE of near 1700 j2/kg2 (RUC) and now near or above 2000 j2/kg2 (NAM) , see no reason not to include the chance of thunderstorms in the post, especially from near or just east of MCO and along I-4 to DAB southward toward Vero Beach and eastern Osceola Counties. There is a smaller chance near West Palm, but believe any earlier activity in this area as depicted by the latest RUC will be showers.


Lastly, all forecast plots show the inversion in the lowest few thousand or even hundreds of feet to break, with none present by late afternoon. This should allow ample sunshine and the west coast sea breeze to work inland and modify while traversing the heated , and dry grounds now in place on the west side of the state.  

In closing for today, The Storm Prediction Center nor any official offices are discussing thunder today, and barely even showers, at least not as of the time of this post...so perhaps all of the above should be taken with a large grain of salt and dash of pepper over the left shoulder. Models have been very consistent with showing showers today though, and with higher CAPE now forecast than previous day, I'm willing to roll the dice and take the leap to thunder. Main con will be lack of low level forcing and no truly discernible trigger . But again, sufficient low to mid-level vertical (upward) motions are shown, especially toward Southern Volusia and all of Brevard.


TONIGHT:  Showers to end by mid-late evening if not sooner. Low clouds again possible with mild temperatures much like last night.


WEDNESDAY: Stacked ridge axis across South Central in the absence of apparent triggers should yield rainfree skies, cloudy to partly cloudy by afternoon with highs in the lower 80Fs, and some mid-80Fs where the best cloud breaks occur.


THURSDAY/FRIDAY: Frontal boundary to work down the state, and reach dead central shortly after  nightfall. Showers and maybe some thunder to accompany the boundary, reaching the CDL toward late day. Best chances of rain extends as far south as Sebastian to Vero. Frontal passage accompanied by a quick wind shift over the course of 4-8hrs to the NE and eventually ENE Friday. The boundary could work as far south as West Palm ...underdeath the mid-level ridge which will remain locked in place. Any rains from  Friday morning through Saturday will be post-frontal under speed convergence and some instability behind (north) of the boundary.


SATURDAY: Latest GFS is falling back in line with many of its previous runs with a good chance of showers working back north late Friday through Saturday. The prime culprit appears to be a vort max and associated moisture evolving NE of the Bahamas that rotates around the western periphery of the midlevel high pressure over South Florida. This area is forecast to move into East Central and finally taper and wane toward NW Florida Saturday night. Thus, rain chances seem to be a good bet from Ft. Pierce and north from Friday mid-day and working toward St. Augustine and inland during the day Saturday into early Sunday.

Slight Chance of Coastal Showers Tonight, Possible Showers/Thunder Tuesday

Red areas show Moisture working north and up the state from South Florida, moisture being drawn north from the Gulf ahead of a frontal boundary, and lastly moisture converging ahead of the frontal boundary itself across the Southern Plains through the Ohio Valley over night tonight.

LATE TODAY/NIGHT: High pressure ridge axis at the low levels extends across North Central Florida and will drop slowly south and off shore through Tuesday as a frontal boundary approaches the state very slowly through early Thursday. In the short term (late today and through tonight), moisture is being pulled northward around the western periphery of this low level high pressure center located near Bermuda, while warm air aloft is also being drawn north and up the state around a mid level ridge located close to the low level ridge. Moisture with a lifting cap aloft overnight could promote low topped ocean showers near the Treasure and Space Coast under the gentle over-running or roughly north of Ft Pierce to Port Canaveral at almost anytime between 5pm and 8AM Tuesday morning. Meanwhile, a very shallow subsidence inversion should take shape fairly quickly with the setting sun further from the coast and warm ocean waters. During the late evening, expecting low ceilings of stratus clouds to form, with a few areas of patchy dense fog well inland and away from heavily populated areas where low level cooling will be greatest especially toward West Central and north toward the western Subs of Orlando, Ocala, Gainesville, and much of interior North Florida/Panhandle. There could be some low stratus or thin fog as well almost anywhere prior to midnight, but believe the prevalent mode closer to the east coast and especially SE Florida will be broken to overcast sky conditions of stratus clouds.  Net result, warm overnight lows in the low 70Fs with dewpoints already approaching that level this afternoon as can be seen below:

Pink areas indicate 70F + dewpoints as of now (while typing). The temperature tonight will not fall below those levels....and will unlikely make it north of the aforementioned low level ridge axis which will drop to central Florida, or roughly the Central Diving Line (CDL) from Port Canaveral to Tampa Bay area. Showers most likely from the Port toward Ft. Pierce tonight, with the most dense of fog in the areas of Green and Yellow shown above where surface temperatures will cool the most under warm air over-running.

TUESDAY: Clouds will be slow to break initially, and hoping to be see plentiful sun by 11-noon. Winds generally SE-SSE at 10-15mph, with highs inland in the lower - mid 80Fs and closer to those of today along the immediate coast (near 80-82F) prior to development of additional clouds. Inland highs are tricky, and suspect that mid-80Fs might be optimistic for the warm air lover, since heating could simply lift and break the stratus deck and transition it  to plentiful cumulus clouds, with only a brief period (less than one hour) of full sun is that's possible. 


With the lower sun angle given the time of year (the longest days are only a little more than a month away)...lower 80Fs seems more likely. SSE-S winds along the east coast combined with a weak west coast sea breeze could result in a sea breeze convergence well away from the coasts toward 4pm, but some showers could form along the west coast sea breeze mainly toward the northwest side of Lake Okeechobee initially. Additional showers and possibly a very thunderstorms as well to run from SE Polk county, through Western or Central Orange County, and north toward the I-4 including  ONF (Ocala National Forest) and Gainesville. The GFS implies  the deepest showers of convective nature will exist along and north of I-4 after 6pm, with some activity moving offshore from near St. Augustine south toward Daytona.  However, that will be contingent   upon how parallel to the coast the surface winds are at this time. Any stronger on shore wind component north of Port Canaveral will kill convection given that ocean temperatures off shore are running in the mid-60Fs there. If winds maintain a South to SSW component or attain one toward sunset, showers or thunder could work off the east coast given that the low and mid level ridge axis' will by now be located near the Southern Shore of Lake Okeechobee. 


WEDNESDAY: Morning fog or stratus is possible once again, but most likely stratus clouds as surface winds could be stronger ahead of an approaching frontal boundary. Timing has been slowing down from run to run (and from time to time), and if it slows down even 6 hours more, fog will again be possible and be more widespread than tonight (overnight on Tuesday).  Although winds on Wednesday  will be S to SSW to possibly SW later in the day, record highs might be tough to attain due to expected cloud coverage, If so, the most likely areas will be near NE Florida along and north of I-4 north of Sanford toward St Augustine. Continued SSE -SE winds over South Florida will preclude record highs in this area, although the region inland of Ft Myers/Naples might come close as well.


THURSDAY: Frontal boundary now expected per model agreement to reach Dead Central toward the MDL (Magic Dividing Line) ever so appropriately but admittedly very' unprofessionally'  labelled by the writer this go around, as it appears it will be within that zone the front will not be able to penetrate much further south. Showers and thunder will be possible along and ahead of the front is it drops from North to North Central from late morning through Sunset, and eventually running into the low level ridge axis remaining across far South Florida's 'saving grace ridge' toward Southern Dade and stacked to 10,000 ft. A frontal passage across north Florida will become near Neutral toward 30 miles either side of the MDL. With that said, best chances of showers and just maybe some thunder as far south as the Eau Gallie Cauesway, but watching to see if this chance won't extend as far south as Route 60 (Vero Beach). A few coastal showers SE Florida but it appears this go-around, most of the state south and near Lake Okeechobee will see very little rainfall from this front, namely because precipitation with it comes along moisture convergence with the boundary, of which there will be none in this area. It is also possible there will be some near record warm overnight lows on Thursday morning...(mid-70Fs), South Central. 


FRIDAY:  High pressure in the low to mid-levels rapidly builds eastward across the Deep South and becomes centered toward the Eastern Carolinas by Friday morning. A wind surge is being depicted to impact those areas only that are behind the locked and decaying frontal boundary, or from Sebastian Inlet and north, if not only the Melbourne beach area and north.  Winds of 18-28mph possible through mid-afternoon. A few showers are possible as well anytime on Friday mostly near where the boundary dissipates (East Central/Space Coast).


SATURDAY: Continued shower chances in the same areas and possibly spreading back toward NE Florida, or roughly anywhere north of a line running from Ft. Pierce to Sarasota, most likely east side. Shower chances should wane by sunset Saturday night, with only some possible sprinkles remaining for Sunday, although this might be optimistic. Cloud coverage might remain an issue over the weekend though either way.

 

Near Stellar Weekend With Moderating Conditions Through MidWeek

Graphic Depiction of Temperatures one hour before sunrise. Ideal radiational cooling  upon North Florida under a calm wind and  clear sky set the stage for an ASTOUNDING record low temperature in Tallahassee of 23F, with numerous mid- upper 20F in locations such as Crestview, Monticello, Cross City, and Marianna. The 23F surpasses the previous record by 4F and  was very hard pressed to be matched  nationwide even at International Falls, Minnesota. It was colder there than in most locations in Saskatchewan and Manitoba Canada to boot,  as well as the Grand Canyon, nearly all stations in Maine, and Aspen, Colorado.  The only location for the most part that out-shined was Mount Washington at 10F with winds gusting to 75 mph , blowing snow, and a wind chill of 19 below zero!  Thanks for blowing it this way Washington. (although, temperatures around where most folks living in TLH were likely much warmer, as this record low was recorded in low/flat/grassy terrain at the airport).

TODAY/SUNDAY: No change in the forecast reasoning of Thursday's post . As expected, lows in the mid-upper 20Fs occurred across North Florida. The very cool to cold air made it as far south as Ocala (34F),Crystal River (34F), and Inverness (39F) whereas the warmest overnight lows occurred from Canaveral and South along the immediate east coast east of A1A to MIA /  US1 to Key West which was around 70F. Winds toward Ft. Lauderdale were already switching to NE and up went the temperature to water temperatures or nearly so as well as Virginia Key (near Key Biscayne) with a pair of 71Fs.


Slow warming through mid-morning inland (but the lows in the 20F will rise into the 40Fs by the time some folks are heading to church), with a quick rebound in temperatures expected interior by 11AM with all locations reaching the low to mid 70Fs as light ENE develops with daytime heating. Skies could be partly cloudy with  'dollar pancake stratocumulus' clouds in passing but little more. Exactly how rich the sky will get with these clouds could be in question. Might see some nearly mostly cloudy skies for a time toward sunset. Neither here nor there though.


TONIGHT: Temperatures near the coast should be a few degrees warmer as well as those along and east of I-95, but interior and west will likely be similar to this morning within 4 degrees of 50F either side.


Winds near calm or light with partly cloudy skies from time to time. There could be some shallow fog by Sunday morning as moisture levels slowly increase from the current level PWAT air of only 0.4 to 0.7 inches under an evening inversion which will quickly disperse with the rising sun contingent upon cloud coverage.


MONDAY/TUESDAY: High pressure responsible for the cold morning which is now centered over South Central Georgia will progress ENE well out in to the Atlantic through the mid-levels. Winds start to become ESE to eventually SE by later Tuesday with the ridge axis across Central Florida and eventually South Central, whereas south Florida remains mostly easterly. Daytime highs near the coast in the mid-upper 70Fs contingent upon cloud cover during peak heating (between 11:30AM - 1:30PM). Possibly another morning of fog ' slim chances' Monday but not on Tuesday.


***Side Note: Ocean temperatures are now running in the mid 60Fs north of the Cape and in the lower 70Fs south of the Cape toward Miami, so onshore winds won't be quite the ticket for truly 'warm' afternoons much longer but will buy us warmer overnight lows than inland counterparts.  Eventually, and might as well say it now, these water temperatures will become a big player in afternoon highs along the east coast north of MLB before year's end and the first few months of 2012.


WEDNESDAY/THURSDAY: By Wednesday the first of two frontal boundaries being transported by 140kt jet stream winds heading across the NE Ohio Valley will already be over the Panhandle. Much warmer on Tuesday most places, but Wednesday seems to be  primarily the best day for temperatures most locations to record something in the lower-mid 80Fs, but again, near parallel winds to the coast could hold A1A readings from MIA to the Cape teasing closer to 80F. 


Winds more SW toward I-4 should allow the readings to get into the lower-mid 80Fs as well. After a slight chance of showers and maybe thunderstorms, mainly North Florida on Tuesday, precipitable water values will have more than tripled from today reaching almost 1.75".  The first boundary could make it toward I-4 on Wednesday with a chance of showers and possibly a thunderstorm or two between I-4 and south to north of Lake Okeechobee, or rather, along and south of  wherever the boundary eventually ends up.  


The second boundary mostly notable by a mid -level trough screaming by well to the north along those strong jet stream winds will progress the initial surface front south toward South Central/South Florida on Thursday, with another chance of showers and perhaps thunderstorms right along the CDL (Central/Magic Diving Line) across the state, with some showers and maybe thunder South Florida. Already though, by now the front is washing out and becoming absorbed in the humongous but 'ovately flat' area of high pressure which will be re-enforced by passage of the front, extending half way to Europe across the Central Atlantic ENE of Florida.


Deep easterly fetch of over 1000 miles, but not very strong results in remaining elevated atmospheric moisture content (at least 1.3") for quite some time to come. This means overnight lows in the mid-upper 60Fs and probably highs in the mid 70Fs contingent upon cloud cover, which could be quite ample at times.


Showers will be possible or more likely sprinkles Thursday through Sunday morning. The next front will be approaching in the generic "7 Day" Time Frame, or perhaps a day or two sooner. Whenever that might be..the easterly flow will be disrupted and end the shower chance, but clouds could continue with more "Room Temperature" days and "Ceiling Fan nights".


**For kicks, watching the Tropics .... Temperatures in the Caribbean are running in the 80Fs round the clock. Last nights GFS showed a Cat 2 Hurricane coming out of the Gulf from where Rina formed last month..taking a solid tropical storm toward the Big Bend by the 27Th. The following run completely dismisses such fugue state of affairs, but it is worth looking for. Plenty of time and Thanksgiving as well before this early Christmas Gift can be delivered. Chances are more probable this figment will be nothing more than a lump of coal as opposed to a shiny Corvette named Tammy.  Central and North Florida experienced a Hurricane/Tropical storm around this same time frame (November 23rd) in 19988 named Keith.

Cold Front Tonight as Sean Peaks in Strength

Morning Visible Satellite Image Shows Cold Front Across The Panhandle and stretching NNE to a large low near James Bay. Tropical Storm Sean as shown relative to Bermuda and generally forecast direction of motion.

RECAP: Cold front cleared the western Panhandle this morning and is nearing Tallahassee. Drainage flow everywhere last night with temperatures ranging through all of the 50Fs to mid-60Fs, warmest SE Florida coastal and Keys, and within 1 block of the beach from Canaveral and south. 


By an odd twist of fate JAX was colder prior to sunrise than Pensacola behind the front at 45F with a calm wind, albeit Pensacola was one degree warmer at 46F but with winds from the north at 20 gusting to 33mph making for a wind chill of 37F under cloudy skies. 


Elsewhere, Tropical Storm Sean has been on a NNE track and is forecast to miss Bermuda to the west. There was a big flare up of convection around 6AM (Bermuda Time) but that has since waned. Sean is now over cooler ocean waters in the mid-lower 70Fs with no Heat Content. Ocean Buoys in this area are scarce, and none of those closer to the storm were showing sustained tropical storm force winds but one. Sean is officially forecast to become a hurricane by tonight, but not so sure about that due to increasing shear and no ocean heat content. A plane is flying into the area as I write, and they might be able to whip up a (convoluted to some degree) ' technically a hurricane' status, but it will likely be very brief if ever and never be measured on the surface from what I can tell.


Sean will start to become absorbed tonight and more so by mid-day Friday by a much larger trough of low pressure now located near James Bay. High Pressure to the N through NE of Sean could push abundant moisture NW ward in strong SE Flow ahead of the cold front away from Sean. Pressure gradient winds along the coast of Nova Scotia to Greenland could generate surface winds stronger in those locations than what will be experienced in Bermuda . The latest GFS has Sean nearly gone around the same time the NHC has Sean a Hurricane...so time will tell. Either way, no impacts to land other than indirectly due to high seas and pressure gradient winds between the cold front/Sean/and High Pressure.

Latest Analysis. The yellow area shows the surface low SE of James Bay and then Sean. The broad area indicates how these two features will eventually wed off the coast of New England with  very dynamic results upon NE Coastal Maine and through Nova Scotia. Other rains along the coast of New England will be related to the front combined with some of the moisture from Sean as the umbilical cord is made with the Mother Low near James Bay. In a sense, Sean will cocoon from the state of which it originated, a mere non-tropical or even subtropical entity.

OTHERWISE: Cold front approaching Central and South Florida today. Winds today will be NW with highs in the upper 70Fs to lower 80Fs, mainly South of I-4. Increasing cloud cover precedes the front, and this cloud cover could reach a portion of the region north or near I-4 during peak heating. Otherwise, nothing to speak of other than some light sprinkles possible along and just behind the immediate frontal boundary.


I conjured up a first grab stab   time phased image of the cold frontal position from its current position through the time it will be clearing the state by early Friday. Positions for Central might be delayed an hour or so if the front slows down during the afternoon during heating of the day, but either way...it goes through well after dark:

TONIGHT/EARLY FRIDAY: The cold frontal passage tonight will be easily diagnosed by a surge of NNW winds of 20mph possibly gusting toward 30mph for about a 6 hour window of time from North Florida through most of South Central during which time the temperature will drop 10-15F degrees.. This surge never reaches South Florida to such extent but the cooler air does. Skies could be partly to mostly cloudy all areas for a few hours prior to and after passage.


Morning lows Friday  should range from the mid-upper 50Fs east coast from Canaveral South (warmer toward the lower 60Fs coastal SE Florida), decreasing west of the Intracoastals and down into the mid-upper 40Fs interior and west as far south as Lake Okeechobee. Friday will be the ODD (one day deal) for the east coast from Canaveral and South as far as the coldest temperatures are concerned. Winds relax late morning, but will likely pick up again with daytime heating under clear skies, and with mixing during peak heating range in the 15-23mph range across the state as winds slowly veering toward due north by Sunset. 


Big downfall to all of this. Very cool afternoon Friday, with highs barely getting above 60F toward Ocala and north, and just eking out a low 60F near DAB with breezy N-NNE winds around 18-23mph with mixing during peak heating. The main period of cold air advection will occur coincident with peak heating on Friday well behind the front, which will be a saving grace from what could otherwise be a very cold morning had timing been different.  The NAM is showing a near classic JAX Cold Wedge working into the north side of the Cape approaching the Port, but thinking for now it's too early in the season for those shenanigans, so discarding...highs other areas all of Central (except Tampa Bay) in the mid-upper 60Fs nearing lowers 70Fs coastal South Florida/Keys.


SATURDAY: High pressure will be building across the Deep South and northern Gulf and be center near Southern GA Saturday Morning. Very light winds and drainage flow could send temperatures near I-10 in select areas like Crestview, Marianna, and Tallahassee into the mid-upper 20Fs with widespread 30Fs (frost looks possible as well in these areas). Elsewhere, winds along the east coast of Florida will start to become more NE (and light) overnight, so that overnight lows from the Cape and South might occur well before midnight, level off, and possible rise a few degrees before sunrise into the low 60Fs ...mainly within only a few blocks of the ocean. Otherwise, with sunrise ENE winds develop as the high pressure center continues to build NE ward into the Western Atlantic. By day's end a broad and stacked elongated oval of  high pressure will extend well out into the NW Atlantic (close to where Sean demises) SW ward into the SW Gulf of Mexico. The cold event is all but over already for the South half of the state after sunrise Saturday.


SUNDAY/MONDAY: Mildly cool overnight coastal lows but no big deal, cooler inland with possible patchy inland fog. Winds become more east to eventually ESE-SE on Monday as high pressure continues to work offshore in stacked fashion.. It appears some vorticity (energy) from the old frontal boundary by now south of Cuba might get recirculated along the back/western extent of the surface to 850mb high (now well out at sea) late Sunday through early Tuesday. In doing do, showers could work up the east coast from the Keys and far Southeast Florida Sunday night through Monday, reaching dead central toward Indian River/Brevard/Southern Volusia from mid-morning through sunset after clearing South Florida.


Very warm Tuesday/Wednesday. Looks like the East Coast from Ft. Pierce and North will see the warmest days it has experienced in quite a while as winds will no longer be predominantly onshore and across the cooling ocean waters. Thought those easterlies would never end.


Another potentially potent Southern Plains to Ohio Valley frontal boundary which might result in a Quasi Linear Convective System type Squall Line from Eastern Oklahoma/NE Texas into Louisiana and through the Ozarks toward Ohio (as well as Indiana and Illinois) will be on the approach by Wednesday. 


Latest GFS indicates there might be a prefrontal trough ahead of the boundary which might result in some showers ...and who knows..maybe even a thundershower or two..across Dead Central moving offshore the east coast Wednesday afternoon and evening. 


This approaching front never clears Florida as thought (at least so far) but becomes absorbed in the ridge of High pressure which, as it might be, will dominate the states weather into at least early Thanksgiving. The GFS is up and down on rainshowers moving onshore beyond Wednesday with the next washing out front. For some reason, it has backed off on them as of the 2AM model run, which is a new twist. I'm hedging more on showers though given the wind fields it shows.          

Tropical Storm Sean To Lift North Tomorrow /Cold Front Thursday Night

SEAN positioned over 800NM East of Ft Pierce/West Palm this morning. This image shows Ocean Heat content (which is closely correlated to the SSTs (Sea Surface Temperatures) this morning. Note that any further northward motion will quickly take Sean into ocean waters too cool to support Tropical Storm status (black coloring), although winds will remain at Storm Strength well after it clips Bermuda. The brighter colors in orange denote dry air. Note that Florida is in the dry air in the mid-upper levels to well off shore, indicating that shower activity over the state is not related to Sean.

***REMINDER: Nation wide test of the Emergency Broadcast System (EBS) today at 2:00pm EST. ****


NOW: At 7AM all areas are experiencing drainage flow with some small areas of low patchy fog and a very saturated low level atmospheric moisture profile which quickly dries out  500 ft above the ground, more so above 5-6000ft. Temperatures are in the low-to mid 60Fs with a few upper 50Fs everywhere other than direct beach side from Port Canaveral to Key Biscayne and the middle and lower Keys where temperatures are clinging for dear life on 70-72F.   A few low topped showers linger just offshore the Cape with other showers working into far SE Florida.


TODAY: Sean will meander in place today and eventually begin to lift northward tonight. High pressure builds NE ward from the SW Gulf as the high pressure wedge down the Eastern Applachians that had been creating the pressure gradient retreats NE ward as well ahead of an approaching cold front and that front's supporting upper level trough.


Winds today to become more NNE at 10-20mph with strongest inconsequential winds down the Barrier Islands/Intracoastals along the entire east coast, with a period of such winds in the mid-afternoon inland as mixing works out the low level inversion that is trapping the moisture close to the ground this morning. Low topped showers, mainly sprinkles but the dominant mode will be decks of flat topped stratocu mainly over the Southern Half of the state, with more dense clouds of various altitudes across North Florida ahead of the approaching frontal boundary. Temperatures like the past two days, with highs at the beaches in the mid-upper 70Fs  with some very low 80Fs interior/west/and south Florida. All in all, highs will be dependent on cloud coverage (where it will be located) during peak sun angle hours.


TONIGHT/EARLY THURSDAY: Winds become light NW well after dark and shower chances end with cooling temperatures everywhere. There could be some lower ground fog almost anywhere by morning with dewpoints remaining steady state close to the ambient air temperature, with lows in mid-50Fs everywhere except near any body of water where lows will be in the low-mid 60Fs.

Morning enhanced infrared satellite image shows Sean well to the east of Florida and a projected track for starters. Surface front in light blue and the high pressure building into the Gulf and down the Appalachians. Sprinkles possible, mainly the South Half of State, with patches of stratocu resulting in sky conditions varying from sunny to mostly cloudy for brief periods in a few select TBD locales. Meanwhile, Alaska is dealing with a No-Named Hurricane Equivalent Storm of its own, one perhaps of intensity this time of year never equaled except maybe once in recorded history.

THURSDAY: NW Winds of 10-15mph during the afternoon with highs near 80F to lower 80Fs, but cloud cover will be a key factor in this variable, especially across Dead Central where it might end up being in the lower to mid 70Fs. Front appears will go through Panhandle dry. As high pressure in the Gulf continues NE ward (and pushes Sean further north and east), pressure gradient winds behind the front will already be in place over the Western Gulf. Moisture convergence during a brief window of opportunity behind the departing high and ahead of the front could result in some sprinkles or showers 30 miles either side of the Magic Dividing Line (MDL) running from Tampa Bay to Port Canaveral from early afternoon to sunset 'ahead of' and 'as' the front passes through.


THURSDAY NIGHT/EARLY FRIDAY: Cold front then to cross from NNW-SSE down the peninsula, crossing the MDL around 10:30pm. Front to be followed by PERHAPS gusty winds right along both the West and East Coasts from JAX - Ft. Pierce (on the east side) of 18-25mph for a few hours overnight. It appears these will stay offshore the coast further south, and be greatly reduced by sunrise or shortly thereafter as the high pressure continues NNE ward.


FRIDAY: Cool all day with highs in the upper 60Fs to near 70F along the MDL and cooler North with some highs north of I-4 never making it out of the 50Fs. South Florida / Keys should reach the Middle 70Fs..all with north winds of 15-22mph making for a very cool, fall like day under mostly clear skies.


FRIDAY NIGHT: Circulation around the high which will work well NE ward to the NW Atlantic and SW ward into the SW Gulf of Mexico results in NNE-NE winds overnight. The immediate east coast from Port Canaveral and South should level off in the quick temperature fall that will ensue with the setting sun, and actually warm a few degrees prior to sunrise, remaining essentially in the lower to mid 60Fs while inland lows vary from the low 50Fs to mid 40Fs as far south as Okeechobee, and even cooler from Ocala toward the Big Bend and Panhandle region.


SATURDAY: With a cool/cold start early winds will become ENE everywhere by late morning with a rapid warm up into the 70Fs with sunny to scattered skies working onshore by early afternoon. Winds in the 10-15mph range and 70F's to make for a stellar weekend with similar conditions on Sunday.


BEYOND: Much of next week will be more of the same with overnight lows gradually warming as air mass modification (rising dew point temperatures) is prolonged with continued ENE-E flow. Any windier conditions (above 18mph) will be restricted to the Southern 1/3 of the state. There might be some low topped sprinkles toward South Florida by early to mid next week, but not worth the mention in a forecast highlight.


NEXT WEEKEND: So far, it continues to look like the weather this coming weekend won't be that of the following weekend per the GFS Model. Warmer with overnight and daytime highs remaining in the 70Fs at the coast and 60Fs inland with highs near 80F or above interior and west, cooler near the east coast everywhere . E winds becoming ESE-SE as the next front will be on the approach by next Thursday (right on cue). It still appears this front will reach Central, this time becoming absorbed quickly in the prevalent dome of high pressure over the southeast States toward coastal South Carolina. Not once in the past 4 days (and 16 model runs) has the GFS showed a clear cut frontal passage. Numerous showers  with moisture depth reaching upward toward 8000 ft (as opposed to a shallower 5000 ft) would result in measurable rainfall, mainly over the Southern 2/3 of the state with the higher totals within 40 miles of the East Coast from Brevard County and South.  

Sub-Tropical Sean With 45 mph Winds Spits at Florida East Coast Today

Sub-Tropical SEAN is seen in this enhanced water vapor image from early this morning. The system has winds of 45mph and will likely strengthen further during the next 48 hours as it remains nearly stationary and eventually drifts toward the west to northwest before entering cooler waters. Also shown is the ridge of high pressure (zig zag line) down the East Coast into the Gulf and flow around it. Florida is in 'dry air' and our activity is not related to Sean other than very indirectly at best, but directly in the sense of the long period and large ocean swells. Cold front moving through the Southern Plains with upper level low shown over New Mexico. That low will move toward Western Michigan track the front across Florida, while the low will be far removed in NE Canada. Best chance of severe today shown in solid lavender with other areas in the dash lavender (but not all inclusive) possible. ..for presentation purposes only. The problem being presented today for severe further north is not unlike that which happens in Florida along the Magic Dividing line. The best wind profiles will be far removed in western Michigan, whereas all the instability will be near and south of the Arklatex Region several hundred miles away. The difference with these events in Florida is that the two regions are separated by, well, almost nothing.

OVERNIGHT: Decoupling and resultant drainage flow was more expansive last night with only the Cape toward West Palm Beach remaining in NE winds ( along and east of US 1), as well as a small portion of far NE Florida near JAX. Net result was cool temperatures in the low to mid 60Fs many areas as far south as Okechobee, with Homestead near Miami having the same temperature as Pensacola before sunrise. In the areas not affected by the factors of decoupling and drainage lows remained in the low 70Fs (Cape to West Palm) except far NE Florida near cooler ocean waters and less direct flow off the ocean. This can be best seen by the well past sunrise temperature schematic which shows temperatures already rising along the east coast where onshore winds of 10-20mph today will prevail...with some coastal sprinkles being the dominant mode of activity today mainly along and east of the light blue line.

TODAY: Coastal highs mainly in the mid to upper 70Fs (South Central/South) near the warmer ocean waters but prevailing mid to lower 70Fs further north. Inland temperatures in the upper 70Fs to near 80F.


Morning RUC and North American Model (NAM) forecast soundings indicate a very strong subsidence inversion just below 5000 ft this afternoon that would not support rain, with the prevalent modus operandi being banks of vertically challenged pancake stratocumulus clouds which could pass well inland and across the state. Daytime heating should lower dewpoints inland, so not sure even a sprinkle will be found west of I95 except toward South Florida. There are bigger gaps in the cloud field per satellite imagery than of yesterday, likely due to the better organization of 'now Sean' and  increasing subsidence around the western periphery (far removed from the center) as anticyclonic flow starts to encompass the storm. A sample forecast sounding shows how shallow the moisture will be today if the NAM is correct.

NOTE the dewpoint and temperature lines above and where they separate below 850mb which by standards is at 5000ft. Looks like a sprinkle day with a brief shower possible only at the beaches. This inversion was maybe 1000 ft higher yesterday at best, but every inch counts under the circumstances.  This sounding equates to spittle driplets. 

  MEANWHILE: Sean is well off to the east and is centered somewhere roughly a few hundred miles east of West Palm. Models have all seemed to initialize it too far north by 50-75 miles. No matter. The storm is nearly stationary and seems to be getting better wrapped up. Sean is meeting critieria of being a '27'...near the 27th latitude and hovering over 27C degree ocean water temperatures (which meet those necessary for tropical storm formation). Waters cool SUBSTANTIALLY north of the latitude of Jacksonville well out at sea toward Bermuda. Regardless, the storm could still become better organized and start to look more impressive on satellite imagery through Thursday.

Green line shows the western extent of the circulation per cloud types. The lavender lines along the east coast of Florida is the area that onshore winds blew all night (where the atmosphere did not decouple and/or where drainage flow was not experienced, thus warmer overnight lows). The orange arrows show the flow before sunrise. The yellow indicates low clouds or thin fog closer to the ridge axis noted by the blue zig zag.  

Per satellite animations so far this morning, it looks like the best chances for any actual showers will occur over Volusia and North Brevard toward late morning and early afternoon...but other areas could get in on the action at any time after 2pm, but not be a big deal.

TONIGHT/WEDNESDAY: Suspect that almost everywhere might fall prone to drainage flow, but a small corridor could remain free of those affects along the east coast from Canaveral to Ft. Pierce/West Palm once again. Similar temperatures with less chance of showers limited to sprinkles.


During the day Wednesday models have been agreeing that sometime between 11AM -2PM the east coast could fall within the realms of circulation of Sean as the ridge of high pressure pulls out to the NE ahead of the approaching cold front. Shower chances could exist once again mainly within 25 miles of the east coast from the North Side of the Cape to Miami. The NAM is showing ample moisture to support showers but does not depict any. Then again, that has been the case the past few days. The limiting factor though will be how shallow the moist layer will actually be. I suspect it will be a sprinkle fest at best at this point given the trends with winds more northerly with less oceanic effects. The GFS has trended downward with the rain chance.


THURSDAY: Front will be in the Panhandle and lift off to the NNE while crossing the state dragging its non-dynamic tail across the state Thursday night ... with hardly a surface reflection. During the day, winds will be NNW-NW with a cool morning due to drier air now in place due to subsidence (sinking) around Sean combined with drainage down the spine of the state. Thus, the cooler morning everywhere will be a function of lower dew points (less moisture) holding heat in as well as no wind off the warm ocean waters. High pressure in the mid-levels will build NE ward from the SW Gulf further cutting off the moisture supply, but not fully enough before generating rain along the front along and north of I-4 (at worst)...if even that.  The front will clear the remainder of the state pretty much un-noticed until after dark when winds become more NNW.


MEANWHILE: Sean will become Extra Post Tropical and move out as a gale near to or shortly after passing the Bermuda Triangle, eventually impacting indirectly the coastal NE states toward Maine and possibly even Greenland as it heads toward the Labrador Sea and Baffin Bay. Models vary from taking what is left across Greenland to merging 
SuperExtraPostMortum Sean with the other low that will be tracking the cold front across the state (noted earlier in this post), and subsequently retrograding that merger toward far northern Canada south of the Arctic Ocean!:

FRIDAY: High pressure in the mid levels continues to build in the mid-levels across the NE gulf and into the Mid-Atlantic while a surface high builds eastward from Central Texas behind the front. The two combined could send a 'wind surge' of 22-28mph down the east coast, but so far it looks like that surge will narrowly by-pass the coast by less than 15 miles. Either way, after a very cool morning low with most areas in the low 50s-upper 40s and closer to 60F only right on the beach from Port Canaveral and south, due north winds during the afternoon coupled with the already pre-established drier air will limit daytime highs along and north of the magic dividing line (Canaveral to Tampa Bay region) to the upper 60Fs and cooler north, with lower-mid 70Fs graduating (warming) the further south one goes to the Keys (upper 70Fs).


FRIDAY NIGHT/EARLY SATURDAY: Winds clip the coast all night, so the coolest temperatures east of US1 might actually be felt around 2AM and warming a few degrees as winds gradually become more onshore by sunrise Saturday, but similar overnight lows to Friday Morning elsewhere.


WEEKEND WEATHER/BEYOND: Picture perfect with winds becoming easterly post-haste by late Saturday afternoon and beyond (eventually ESE-SE by late Monday). Temperatures round the clock in the 70Fs right at the coast, warming into the 80Fs by Monday South Florida and spreading northward to much of the state Tuesday. Overnight lows warming inland as well, but will still be in the 50Fs most areas until Tuesday morning.


Next chance for showers comes Monday and Tuesday before the next front comes, in you guessed it, nearly exactly one week after the now approaching front passes per this time of year. The next front will have a problem crossing the entire state..or this is at least   possible. The GFS has shown this for several runs day after day, with the front hanging up anywhere from South Georgia to Central Florida. The easterlies to ESE-SE winds with high pressure now established due east to ESE of the state in the Atlantic and increasing moisture could make for a showery weekend before that of Thanksgiving, more 'showery' than this previous regime, but a bit warmer as well.   This is well out in time and will likely change innumerable times before then, but so far the writing has been on the wall for a more wet period heading toward the week before T-Day for a while now.