Increasing Cloud Cover / Shower Risk Central Today - Risk of Strong Storms Tuesday

On This Day , Last Year

There is a Risk that there will be thunderstorms, some potentially strong or even severe (?) come Tuesday, then again more rain-thunder chances on Thanksgiving Day, meanwhile:

TODAY: A cold front currently located near Ormond Beach stretching WSW toward Cedar Key along the west coast is slowly working south early this afternoon. Last hour an area near the Villages was reporting 'heavy rain'. In general  most areas will not see all that much today in rainfall if any, but not everyone will remain completely dry.

Cloud cover associated with the cold front is clearly discernible in satellite animation working south, now already having entered parts of North Central Florida as it works into Central from noon through mid-afternoon.

The front itself is still a way back and won't like make it to "Central Direct ' until near sunset. Wind immediately behind the boundary shifts to northerly with much cooler air that won't   be realized from Central Direct and south until after sunset southward toward midnight (far South Central/South Florida).

OVERNIGHT-MONDAY: Wind overnight will become NNE-NE heading toward sunrise. Areas at  the 'immediate' coast south of I-4, mainly Brevard and South will escape the brunt of the coolest of air associated with the front, likely not falling below the lower 60Fs whereas inland temps will range in the lower to mid-50Fs with the coolest air near Lake County and North where 40Fs will be realized. 

MONDAY: Wind during the day veers to ENE and almost east by day's end. Daytime highs will be similar to the past several days, in the mid 70Fs for the most part.

MONDAY NIGHT-TUESDAY: Pattern shift quickly takes hold as  a Strong Upper Level Jet dive-bombs from Canada south to East Texas and into the far Western Gulf then begins to curve toward the NE, poised toward Florida. In the mid-levels the WSW Flow Aloft will carry some mid-level 'impulses' of energy (vorticity) in the steadily increasing WSW Flow aloft while surface wind remains E-ESE. 

Bulk shear of up to 50Kts,  500mb temperatures running a cold -12- -14C and 700MB running around 0C,  and surface based instability of up to 1000 J2/K2 (mainly south of I4) combined could result in some thunderstorms and other areas of heavy rainfall south of I-10. So far the 'best risk' of stronger storms (if any) appears to be near the Tampa Bay area toward North Brevard southward to North of Lake Okeechobee. beginning late morning Tuesday with the risk running into late afternoon if not even mid-evening..with the better risk along the West Central Coast - though anyone could be game at various locations and varying times. 

Soundings being forecast though, indicate there could be extensive upper level cloud cover which would greatly mitigate the severe threat, though not to say there might be some 'embedded' activity in all that cloud cover that could bear watching.

WEDNESDAY: As of now, looks like a break in the action as the Jet stream continues it race toward Florida. Timing is of great issue at this point however, so nothing is certain in regard to if it will or will not rain much of anywhere this day. For now will hold peace and watch once again for a more active Thanksgiving Thursday.

THURSDAY: Chance of rain , rain showers, or even thunderstorms while bulk shear aloft continues and cold upper level temperatures at 500mb easily below -10C and even 700MB running quite cold as well. It's too soon to say if there will again be a risk of severe or strong storms on Thursday, though for now suspect the bigger 'risk' day might well be Tuesday. 

Not a complete wash out for everyone, but for now not expecting to see much sun this day if any. Cold front to eventually make way and through the state Thursday evening.

FRIDAY-BEYOND: The outcome overall , when all is said and done, will be a complete shift of recent days in the wind fields at the surface. Instead of easterly winds we will be experiencing some refreshing westerlies . 

Temperatures do not look to be anything but climatically normal for this time of year with lows in the 50Fs and highs in the 70Fs.

GREAT BEYOND: Not much of a change in the longer run as winds eventually swing around to easterly well out in time and eventually more southerly. Granted , this is still a long way off, but the GFS is indicating that the last day or two of November into the First Week of December could see above normal temperatures with highs in the 80Fs; however,  previous model runs have shown just the reversal of such fortune, with much colder temperatures.

Will be interesting to see the outcome. The Climate CFSV2 model has been showing 'above to  near normal temperatures other than for a few brief non-consequential ,   cool downs well into mid-December; 'maybe' even well above normal the past few runs going into December (for what it's worth). Though do note, some runs (like the GFS) have been showing just the opposite.

Fall Phase II Begins Today - Winter Like Weather By Thanksgiving?

One Year Ago This Morning -  2016

TODAY: Weak frontal boundary characterized mainly by low and mid-level cloud cover and wind shift to northeast wind progressing southward will lay across South Central Florida near day break along a line near Central Brevard Country to south of Tampa Bay on the west coast. Just ahead to behind the boundary satellite imagery indicates what appears to be rather extensive cloud cover in the lower to mid-levels. There is no rain showing up along this boundary and none is anticipated but for perhaps later today for near St. Lucie - Palm Beach counties.

Wind behind the boundary is from the northeast gusting toward 20 mph and with cloud cover in the offing today, mainly for parts  of South Central Florida and northward, afternoon high temperatures will be inevitably cooler than the past few days other than for areas across South Florida where cloud cover will not be extensive and any affect from the dwindled boundary will be but hardly realized at all.

TONIGHT-SATURDAY: Some guidance indicates the chance of onshore moving rain-shower activity mainly for Indian River County northward toward Flagler County sometime after 2AM Saturday morning with the 4KM NAM model favoring Central - North Brevard to Volusia county initially.

What is to remain of the boundary either way will have lifted just a bit northward  but mainly above ground level. The surface boundary itself will have been fully absorbed into the synoptic scale high pressure area north of the state with little trace of its remains other than a moisture boundary.  No changes will be realized temperature/wind wise at the surface other than a bit of a veering more toward an ENE component. 

 Most guidance does indicate rain however, but exactly where is a tough call. Any rain that does fall would be 1/4" or less. All in all Saturday does not look like a wash-out anywhere, but cloud cover might continue to be a real bug-a-boo.

SUNDAY:  Sunday morning temperatures right near the coast will be closer to 70F (south of Daytona Beach) and cooler just a bit inland, but the bigger change and hence 'Fall Phase II" will be afternoon highs not reaching 80F (though some might see 80F from Vero and South) but more toward the middle-upper 70Fs depending on cloud cover. Chances for now favor upper 70Fs. 

Any rain-shower activity that might occur earlier on Saturday  will have worn thin and made history.

Otherwise, this day looks to be characterized by typically mid 'fall' like conditions of easterly to ENE wind and  little to no chance of rain -  cloud cover varying from scattered to perhaps a bit cloudy at times. 

MONDAY-TUESDAY: Decreasing cloud cover but not much warmer with highs remaining in the 70Fs . Coolest locations in the morning inland from the immediate east coast (where closer to 70F will be realized). 

WEDNESDAY: Another back door front presses down the state either later Tuesday into Wednesday. This front will only serve to re-enforce the air mass already in place. 

Rain chance  with this boundary appears to be even lower than with the one currently at hand. The difference with this boundary is that   cooler morning lows might be realized  along the immediate coast (lower-mid 60Fs and 50Fs inland).  

Those temperatures look very close to being 'here to stay' for the most part, though the GFS might be over-dramatizing the situation a bit (which would be typical for that model). 

Overall it looks like 80Fs will be increasingly few and far between and hence the 'Fall Phase II" period.

BEYOND:  The current trend is for continued cooler with this second boundary's passage, but with a lighter (less breezy conditions) wind from more of a northerly component come mid-late week. 

 The GFS is flopping around quite a bit lately heading toward the week of Thanksgiving and in parallel is the Climate CFSV2 model showing a similar picture.

 That being, not one , but several cold air intrusions beginning any time from around Tuesday of the week  of Thanksgiving to the day after Thanksgiving, and in both cases , it just goes downhill from there. 

By cold is meant  widespread morning lows in the 40Fs if not some 30Fs accompanied by the expected gusty winds (and wind chill factor) that herald in  'goodbye to fall'.   

 How reliable is that portion of the outlook? Not necessarily very, but then again: 

The CFSV2 was showing what the blogger would consider the 'typical first cold blast of the winter season' to occur during the first week of December (two days ago). History has shown that in many years the period between the 4th - 8th of December might be seen as a 'classic time frame' for that first true 'wintry feeling' cold air mass to intrude into and across the state. Such abrupt changes take a bit of getting accustomed to as coats suddenly get hauled out of hibernation.

However, the last run as of last night suddenly shifted that to Tuesday of the week of Thanksgiving, though the GFS which was showing something similar suddenly backed off. These discrepancies indicate the increasing disparities and uncertainty in long  range forecast model skill. 

Both of them  attribute any said wintry blast'  to a very large area of low pressure, and re-enforcements to it,  forming over the Eastern Great lakes and into Northeast states  with nowhere for the low to go but sit in place and deepen as it extends well into the Deep South -- with Florida being on the receiving end of air flowing southward along the back side of 'said prognosed region of blocked low pressure'.

For now, such speculation could well change.  On the other hand, one way or another, days ahead for those who favor truly cooler to colder dry weather is showing up on the horizon, if not for now, only hypothetically.

November 23, 2016