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

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

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

Monday, November 28, 2011

A Prelude to Winter Begins Tonight

Mid-Morning position of Surface Cold Front and weak pre-frontal trough in the Eastern Gulf of Mexico (GOM). Both will tandem to the east, with the leading edge of   reaching the Central Interior during early to mid-afternoon, then east of I-95 toward 4pm and thereafter into the evening hours.
Wind barbs and fronts alone do not provide the mental image we need to envision what the boundaries will mean when looking outside. The vehicle to provide a future reference point is the visible satellite image. The fronts have been recreated here for reference....the green shows how the band of showers and rain are aligned with the front, so timing from this can be extrapolated eastward with time. With some daytime heating expect to see more clouds anywhere , but the will not be of much consequence until at least early afternoon toward Orlando (as a reference point), but will spread to the immediate coast after 3pm or so. Showers as well. Note the extent of cloud cover behind the cold front over the Gulf yet to come well after the front has moved east of the Florida Peninsula.

Lastly, from a broader perspective, we can observe here that the surface features are contained within a 3 dimensional entirety , consisting of this mid-level low pressure system well as an upper level low (not shown here). 

Within the mid-levels toward 8500 feet overhead resides a deepening low pressure area. The 'spokes' in light blue represent for presentation purposes only of further discussion below how there will be three fronts to move across the state today through Wednesday evening. Each passage will evoke a slowly drying atmospheric moisture profile throughout the columns in the vertical, with the second and third spokes being the primary contributors within that process.  

TODAY: Wheels in the sky keep on turning, and today's is rolling across the Southern Mississippi River Valley Region and the Deep South  with more than one attendant surface low. The surface to mid level lows as shown in the above are both contained within the Mother Load..the upper atmosphere. The mid-upper levels are almost stacked overtop each other. As history tells us, that means slow progression of the ensemble as a whole, so it will be with us through the remainder of the week in various forms. Possible rain rain impacts are the first and foremost variable of interest since they  will be first realized.

SSE-S winds today at 10-20mph with gusts to 25+ perhaps over the waterways. Partly cloudy skies earlier with cloudier conditions spreading toward the east from the west coast during late morning and into the afternoon. Timing of features per close model agreement places showers/rain near  Orlando (and north) around 2-3pm and on the immediate east coast in the  5pm time frame. 

Not everyone will see showers today, especially locals who live toward the east side of the state along and south of the north side of Lake Okeechobee. Thunder is not expected, although a few rumbles are not entirely zero'd out ...just highly unlikely.  The atmosphere is neutral enough in the instability parameter such that it would not be an issue. 

The main impacts are cloudy skies, breezy, and showers from late afternoon through 8pm or so in the area north of the less likely area to the south. Winds will become SW-W-WNW shortly before, during, and after passage of the two boundaries...which will clear the entire state after midnight ..apparently most definite prior to sunrise all locations.

TUESDAY: Mainly West winds at 10-18mph G 22. Partly cloudy after a morning low in the lower 60Fs far east to mid-50Fs interior. Cooler tomorrow with highs in the upper 60Fs to lower 70Fs South Florida. In all cases, cooler north of I-4.

WEDNESDAY: The second boundary/front will be moving through late in the day after another cool start in the 50Fs and low/mid 60Fs. This will be the first influx of truly (noticeably) drier air. Passage of this boundary will take the winds toward a definitive NW direction over night with falling temperatures to a greater degree as the drier air moves in.

THURSDAY: The second boundary now  having cleared the state with much drier air (lower dew points). Lows in the low 50Fs to upper 40Fs many areas except the far north (colder), and south (warmer). Very cool Thursday afternoon with highs in the mid-upper 60Fs with much clearer skies by now if not sooner on Wednesday. Hoping for 70Fs though, which is not out of the question.

FRIDAY: Round -the- wheel goes as it lifts toward the eastern Great lakes. The final front will have to approach from a much more northerly directory, with N-NNE winds to follow during the afternoon. Timing will have to be re-adjusted in regard to exactly when this will occur. Some clouds associated with this feature, followed by a warming trend through the weekend to seasonal norms.  

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Sunday, November 27, 2011

Fairwell Warm Weather Friend...Parting is not Sweet Sorrow

5PM EST Rapid Update Cycle (RUC) model depiction of surface cold front for today in its last model run
This front will approach from the west with a fairly rare but steadfast north/south orientation, making only slow progress into most of Monday as the supporting mid-level low only recently becoming apparent forms in the yellow area for descriptive purposes.  In Green is where the best chance of measurable rainfall with the front itself seems the most probable as of this time, with the area in orange a thunderstorm area to be honed in on for future reference but in no way definitive at this stake.   

TODAY THROUGH NOON MONDAY: Very little change from what we are seeing over Central and South Florida as winds continue from the ESE-SE at 10-20mph with higher gusts at points in time almost anywhere depending on the daytime heating and any manifestation of nearby low topped sprinkling showers which dictate near by conditions (a few stronger gusts/slightly cooler due to cloud cover) - of which will be few and far between.  

Animation of early afternoon visible satellite imagery indicates that most areas other than toward NE and SE Florida will see more sun than clouds, although this could change come   lower sun angle time of day , but not of significant due cause. Otherwise, temperatures running in the 70Fs with some lower 80Fs away from the east coast north of Ft. Pierce and toward the west of I-95.

By noon Monday, the cold front should be approaching if not nearly on the west coast of Florida, with winds becoming more southerly at 10-20mph with similar if not slightly warmer highs along  a low" 80Fs more common" thread. Showers and possible thunder over the Panhandle toward Tampa with time, possibly as far south as Sarasota and eventually Punta Gorda west coast, with a few showers possible east side south of Daytona as the afternoon wears on, but those would not be related to the approaching boundary on the west side.

MONDAY NIGHT: Cold front, due to its orientation as shown above, will clear from west to east   along a common longitude, passing  or clearing for example I-95 within nearly the same hour from Daytona Beach to Miami..which per the latest NAM, GFS, and ECMWF (yes, the models have finally reached near mutual concession to agree)...around 7:30-9PM Monday evening. Best rain chances as indicated above as well, but most anywhere not shown here could receive showers as well. The least likely area appears to be SE Florida the rain realm...but we can't know definitively until some rough spots in information get ironed out. 

TUESDAY-THURSDAY: To skip back to the previous paragraph, it could be that the precipitation to occur from west to east Monday afternoon through mid evening will actually be along 'PRE'-frontal boundary, with the true front yet to cross the state a day later. In either case, it does not seem to have an effect on sensible weather, only wind direction. 

West Winds after the trough presses to the east of one's location with rain chances quickly dwindling and over by sunrise Tuesday. Much cooler air could come in two phases but the sum total of both would be mainly to re-inforce the initial surge neither taking away from, or adding to, the numbers. 

Lows interior to south Florida in the mid-upper 40Fs, and upper 40Fs to just a tick above 50F far east side. Colder all areas north of I-4. Afternoon highs warmer than the cold previously  feared (but not surprised of this) on all days into the mid-upper 60Fs to low 70Fs south with westerly winds ticking clockwise toward NW on Thursday with time.

FRIDAY/BEYOND: Preliminary. Somewhere in the scheme of things heading toward next weekend another front will be making an appearance. Ironically, this cold front could come in the back door, from the North to NNE as opposed to our incomer from the west on Monday. Ironic because it is behind this front that conditions actually warm due to the wind becoming N-NNE-NE behind it. More implicitly, cold air will be modified as it blows across warmer ocean waters with a net result of a return to the old "stratocumulus clouds, warmer overnight coastal lows, and comfortable afternoons in the 70Fs with the ever-present chance of sprinkles of maybe showers somewhere along the line"...too soon to say.

CONCLUDING THIS POST: It continues to look like it will be much cooler to almost cold Tuesday through at least Thursday morning, and probably Friday's as well...with temperatures running below normal. This expectation in and of itself would not be of much perceived impact t'were it mid-winter, but we have been running above normal for quite a while, so these colder temperatures brought forth with a period of some winds in the 10-20+ mph will add the wind chill factor in. Cannot recall  the last time that was even of concern. Looks like the A/C can go for a while...but what of the heat? Individual preference , "You Be The Judge".    

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Friday, November 25, 2011

Black Friday Forecast Frills - Bleak or Best Buy?

For image's sake, this is what the clouds over the state look like from above this afternoon, compliments of satellites above which relay the information down to planet bound denizens  

TODAY Through SATURDAY: High pressure just to the north of the state is slowly sliding east with Florida in the return easterlies behind its clockwise circulation. Moisture is just deep enough to generate the clouds as seen here and if you look outside, there as well (in most cases). Otherwise, winds from the East to ESE at 10-20mph with some higher gusts and highs in the mid-upper70Fs are the prevailing modus operandi through Saturday, although it could be  a few degrees warmer (especially than those of today) toward the Panhandle.  Shower chances are not zero, but even if they can manifest, they will be so light as to be considered 'no impact sensible'. 

SUNDAY-TUESDAY:  Sunday's winds become  SE-SSE (if not South), with temperatures running into the upper 70Fs - lower 80Fs (most likely). From there begins the dilemma. So, rather than provide a detailed  and quite laborious task of synoptic scale differences between each model at various atmospheric levels, we can look at why this is the case at hand in the first place. This can be best performed by observing a few discrepancies between the weather models used to forecast temperature, rain, and wind based on the mathematical equations employed by each without going into detail.

ASSUMPTION (S): It appears that there could be some interseasonal variations being detected or in process but which have not yet come to fruition. Most readers will have heard of La Nina which seems to be running right about normal (in many years it is not present, or the counterpart Le Nino is in force).  That is a factor to consider. Then consider this possibility: the Madden-Julian Oscillation, affectionally referred to as MJO (as opposed to having a MOJO). Yet still, perhaps the North Atlantic Oscillaion (NAO) might also be scheming an attack to ruffle  the forecast's feathers. Point is, given the time of year , climactic winter on the very near approach and variations within this time a near given initially, combined with those additive factors,  each model by all appearances seems to be weighing one of more of those variants into their equations..but providing astoundingly dissimilar results.  Examples:

The Global Forecast System (GFS) Model: Front to cross the state overnight Sunday night, accompanied by rain showers for at least the north half of the state, followed by a significant cold down. Lows in the upper 30Fs (north) through the mid-40Fs south by Monday/Tuesday time frame, with highs never breaching 60F most areas. The GFS of this morning shows these very cool to near cold (as well as very dry) Floridian conditions to prevail through early Wednesday . Well below normal. The next front arrives after perhaps 18-24 hours of slight warming before yet another re-enforcing front comes through dry...and more cold air of similar consequence...a long cold week by standards of the past 8 months.

The European ECMWF model on the other hand from last night does not have the front going through until sometime toward late Tuesday or early Wednesday. Additionally, it forms a surface low in the eastern Gulf of Mexico just off Cedar Key...with much more time for southerly flow to prevail prior to frontal passage. That would allow for not only deeper moisture to be in place prior to passage, but also create a set up much more favorable for thunderstorms as well (perhaps severe). Frontal passage was generally indicated sometime Wednesday at the latest per this model's bidding.

The NoGAPS and Canadian Models fall somewhere in between the two, with the CMC (Canadian) coming closer to shaking hands in agreement with the Europeans. Then again, the Navy NOGAPS model sides with the GFS,  not exactly...close, but slower.

Eventually, something resembling a model treaty will evolve , likely (or hopefully) by Saturday evening. By the time we reach Sunday should be completing signature, but we will have the opportunities to see in each and every subsequent model run of each player just exactly what the TREND is.

If only it was as easy as going to Best Buy to know right now.  The common remark made by National Weather Forecast offices in these cases sums it up neatly and simply,  "Stay Tuned" (the old fall back, "A word of the wises, be prepared for surprises" could aptly work as a second opinion of opinions.) Or as Confucius Say, "Forecast Model Not For Sale, Look at Sky and Figure out yourself".

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Wednesday, November 23, 2011

Several Weather Changes Next 7 Days - Gentle Intro to Winter

In blue are generalized cool front locations as noted in the time-phased image shown. Coverage of showers at any one time will not be extensive and will be mostly associated with the front itself upon approach and passage

TODAY: Cool front across the Panhandle to make slow progress into Central Florida from early afternoon through sunset. A prefrontal trough associated with the radar echoes shown in the image above  is damping out, as such are the showers. Increasing cloud coverage to spread across Central (some already in place), with breaks in the clouds to allow highs today to reach the upper 70Fs to around 80F or so. Warmest S. Florida by a few degrees , not significantly so. Using a combination of morning RUC and NAM, the RUC appears a little fast. Likewise, perhaps the NAM is too slow. In combination, it appears another diurnal pre-frontal trough will form across the CDL (Central Diving Line) Zone this afternoon with daytime heating and hold tight, allowing the cold front itself to play 'catch-up". This will for whatever can be mustered up with cloud breaks as the front progresses only slowly SE ward from North Florida to provide a focus for rain to happen chance.

Suspect much of North Central will be stabilized/hampered by greater cloud coverage from the pre-existing trough that is moving out this morning, and so rain there should be limited to sprinkles and a few spits. Further south toward Dead CDL, cloud coverage will be less extensive. West winds all day, possibly becoming WNW behind a pre-frontal trough North Central (and prior to the actual front).  Winds from surface to well aloft will be mostly unidirectional (from the same direction) with height, and instability will be severely hampered by cloud cover and be mostly surface based due to mulit-layered clouds. Thus, the better chances of rain today/tonight appears will occur along and south of the secondary pre-frontal trough from Brevard County, possibly part of Orange/Seminole and south toward Miami (with time overnight as the front moves in that direction).  If there is to be any thunder at all, it should be elevated type harboring mostly incloud or cloud to cloud lightning, but not feeling very strong on any of said activity. If so, Brevard to Martin County within 20 miles of the coast.

The image above shows general locations will the front should be today through early Thursday. It currently appears that a "diurnal frontal stall cycle' will occur near I-4 to Dead Central during the mid-late afternoon, with no clear delineation as to exactly where the front is located until after dark once that cycle is complete. From that aspect, the front will be free to plow through toward the Straits by sunrise if not before.  Best chance of showers appears to be when convergence/low level winds sync with the time phased diurnal cycle combined with the fronts location near Central as high pressure builds east across the Deep South region toward Georgia. This puts the best covergence/abrupt wind shift on the east side of the state toward Southern Volusia / Brevard region around 8pm as the front will be close to there.  All in all, most people today will not receive rain under partly to mostly cloudy skies and west to West Southwest winds around 10-18mph this afternoon. At some points (or points), skies will be cloudy, but for residents across South Central and South that will occur after sunset.

TONIGHT/THANKSGIVING DAY: Front to press south and be followed by a NNE-NE wind by sunrise most locations (after veering overnight from the NW).  Sunrise should yield a Thanksgiving Day with lows in the lower 60Fs and 50Fs north Florida, warming to the mid-upper 60Fs toward Central and upper 60Fs to lower 70Fs South Central to South. Cool and breezy day with winds from the NE at 15-22mph, gusts toward 28mph. Looks like possible Lake Wind Advisory conditions and Small Craft Advisories might be required. Stratocumulus clouds, but not extensive to follow by mid-late afternoon. Not all that much warming during the day, perhaps up it about 5 degrees from morning lows as already modified cool air advection sweeps across the state from off the Atlantic.  In short, breezy and cool with some clouds. For Friday, NAM continues with bringing in rain showers most of the east coast by morning or shortly thereafter with a nearly saturated atmosphere from the surface to 5000 ft. This seems like 'overplay", and if even so, having a hard time rationalizing anything but more clouds as opposed to showers.

BEYOND: Next front to impact the state beginning Sunday through Monday. Rainfall appears will be more likely most areas with this front, only 4 days later. But hold on, yet another front could follow in due time within another 3-4 days if not less. This next front could manifest anything from widespread showers to isolated thunder, maybe even severe. If so (the latter), it would most likely be for the North Half of the state. Good wind shear but meager  thermal instability being the ever present liability as we approach the last quarter of the year, aka Winter.

As noted yesterday, much cooler from Tuesday and through the first week of December, except maybe for a day or two before the second front comes in to re-enforce Winter's Urgent Calling Card. So far, it doesn't appear it will be extremely cold, just very cool to almost cold (in the mornings) for a prolonged period. Slow and easy...  for easier adjustment without a profound shock to the system.

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Tuesday, November 22, 2011

Are "Winter Like" Conditions Systematically Oozing In Through Next Week?

Today's Broad, Albeit Generous, Brush of where precipitation could fall. The best chances appear to be toward the interior north late afternoon through mid-evening. Sprinkles could occur within the yellows. Nothing beats color coded weather. Wish it was that simple.

TODAY: High pressure off SE Georgia and the Carolinas eventually elongates eastward into the Atlantic to be replaced by ESE-SE flow through late evening, becoming SSW-SW prior to sunrise Wednesday. A potent cold front related complex of three dimensional ferocity will rage across the entire Deep South today into the evening, with possible supercell (rotating) thunderstorms ahead of and imbedded within a Quasi-Linear (as opposed to completely linear) Squall line could   be on the menu of this smorgasbord containing severe category wind gusts as well as hail in association with the cold front which will approach Florida tomorrow.

Meanwhile back on the farm, looks like a good day for bailing hay with summer like clouds across the state, with the greatest concentration of clouds  near the east coast of South Central and north, eventually to make a showing all interiors by early afternoon. A few sprinkles near the coast from Brevard and north (South of I-4) with a better chance of showers near and north of I-4 to possibly St. Augustine by late day. Although Central is in sufficient moisture for showers or nearly so, much of it is being advected out of the area before showers can form. Central is the Source region for regions further north where better convergence can occur along a line running from Tampa, Ocala, toward Daytona and north. Best convergence should be over the interior late in the day through mid evening  in  proximity of that  green box traced out in the image above.   

TONIGHT: Cold front approaches the western Panhandle. Wind overnight becomes SW toward midnight and beyond. Partly cloudy in spots, becoming almost cloudy north. Best chances for fog tonight seem to be interior South Central (South of Orlando) and all of South Florida where winds will be lighter. Coolest temperatures will be away from any clouds which should be South Central, with lows in the lower 60Fs. Warmer further north under the increasing cloud blanket, and further South per common logic.

WEDNESDAY: Main point to observe is that the atmospheric moisture ribbon associated with the front is quite broad. Moisture both precedes and follows the boundary, so clouds could be on the increase from north to south during the late morning and through the afternoon. Winds from the WSW-SW all day, but cloud cover comes with the moisture, so afternoon highs across Central and North Central will unlikely be as warm as they could be otherwise, but South Florida (where the fog will be earlier), has a better bet of the warmest pockets. Highs most areas reach the lower 80Fs south of I-4 ..with some mid-80Fs South Florida before the better cloud cover can move in , which will post-peak heating anyway. 

Cloud cover seems a given to various degrees all North and Central, with the morning NAM showing a better chances of at least a sprinkle both before and after frontal passage. For now riding with the GFS, which implies almost solely clouds, with possible sprinkles/a shower along the immediate east coast East of I-95 as far south as Melbourne. The Cold front ETA for the CDL (Central Dividing Line) is within an hour or two of sunset (most likely after)...progressing toward Miami/Dade toward sunrise, Thanksgiving Day.

Winds behind the front shift to WNW, then NW, then N, then NNE within 11-14 hours after passage, which equates to NNE winds by the time the morning grapefruit and AllBran is being served Central, working toward South Florida by late morning toward Noon Time..

THANKS-N-GIVING DAY: NE-ENE winds ALQDS (All quadrants) at 15-22mph during the day, with some gusts in the upper 20s. Looks like a Small craft advisory type of day, with plentiful stratocumulus clouds working in by early-mid afternoon as well once the depth and longevity of these winds persists down and east of the Gulf Stream waters offshore. Showers unlikely, but it could look like there will be rain from time to time as the sun sets. 

OVERNIGHT-FRIDAY: Continued winds of similar direction and speeds, with more clouds as well. Overnight lows in mid-upper 60Fs to near 70F+ at the coast, especially South/South Central. The NAM is showing incoming showers Thanksgiving Night through Friday east coast. Certainly, upon inspection of the forecast soundings moisture is good, however limited to a shallow 5000 ft,...which wouldn't justify anything beyond a wind blown sprinkle, especially since there is no convective inhibition...allowing any instability to escape into the wild gray yonder. Time will tell.

BEYOND: Per the header in the post this morning, and as previously pointed toward, another front is on the horizon for late Sunday into Monday, just 4 days later...this front could be the harbinger or foreboding of a trend toward climactic winter. In other words, there's ALMOST no turning back now.  The next front will take our overnight lows/daytime highs down a good 8-12 degrees / 5-8 degrees respectively (which is for the first few days of December). 

If the latest GFS trend stands fast, there is yet another front following suit 4-5 days later; thus, once again breaking the old  "One Front per Week" rule of the past month and a-half. Two fronts in a row, 5 days apart is more 'winter like', not allowing for much recovery in the temperatures between them.

This by now third front  being referred to toward the end of the first week of December bears watching....from the active weather prospect.    

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Monday, November 21, 2011

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.

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Thursday, November 17, 2011

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) 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?).  

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Wednesday, November 16, 2011

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.   

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Tuesday, November 15, 2011

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. 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 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.

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Monday, November 14, 2011

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.


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Saturday, November 12, 2011

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.

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