"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".

Sunday, February 26, 2012

Generous Rain/Thunder Chances Monday - Is 'Winter' Over for South Half?

TODAY'S 500 mb/millibar (20,000 ft level)  wind forecast for this afternoon. Continuity  shows that the closed low over Mexico as mentioned in previous posts is no longer evident today, but instead is shown as a mere 'trough' (red line) moving across the northern Gulf Coast. Extensive cloudiness and showers combined with 'evaporative cooling' could keep temperatures in the mid-40Fs to lower 50Fs near I-10. Chance of rain/showers/sprinkles most likely in green, and minimally  'possible' as far south as SR 520 later today and early this evening, albeit not extensively so. Evaporative cooling is caused by rain falling through cold , dry air, evaporating into the drier air toward the ground but causing the air temperature to remain much cooler if not fall more so than would otherwise be expected.

TODAY: Major "Yuck" factor along I-10 today looks to be the agreed upon consensus in model guidance. Extensive cloud cover as short wave mid-upper level trough crosses this area with embedded rain showers, some possibly moderately heavy later today. There is no instability in this fast moving parade of disturbed moisture, and dew points remain very low. Thus, as rain falls in to the dry air it will drag down cold air which will evaporate 'some' of the rain and cause air temperatures to remain relatively low.

The first image was for the  500 millibar (mb), around 20,000 feet aloft ,  level winds. This is for the same time frame at ground level. Breezy ENE-E winds most of today and damp. The low is still evident in the SW Gulf but will wash out later tomorrow. The old front is sketched in (perhaps too far south toward the Florida Straits), but either way..whatever is left of it will work north tomorrow along to where the dotted black line is shown and eventually even further north. The focus of rain will be nearer that boundary...but also out over the Gulf Stream waters east of Central Florida. 
Meanwhile further south of the better rain chances today, ENE wind most of today becoming easterly tonight and eventually ESE on Monday. There is a small chance of rain as far south as the MLB toward SR 520 line, but the gradient of rain to 'no rain' line will be closer toward I-4 on the East Side of the state toward the Brooksville area on the west coast. Highs today in the mid-upper 60Fs most of central due to cloud coverage and  recovery from the meager cold frontal passage the other day. Low-Mid 70Fs more likely toward South Central and all of South Florida. Some showers possible over the Keys for the first part of the day as well.

MONDAY: Cloud coverage continues, so over night lows to remain in the low-mid 60Fs most areas. The area of low pressure that was in the SW Gulf will begin to break up later today..and bits and pieces of 'energy' (vorticity) will traverse across the state as a result after or near daybreak and through the day within a flow similar to what is shown in the top image (above) from west to east.

The main focus of energy so far is depicted to cross those areas that will not be in the rain today. Thus, everyone gets a shot at the rain between today and Monday.  The main difference tomorrow will be that instability will be much more sufficient to make for a chance of thunder most anywhere from North Central through most of South Florida, but South Central to Central seems so far to be the 'target area' for thunder.

This is a FORECAST of jet stream winds on Monday. Note the divergence of winds (separation) over Central Florida. This area is also expected to receive the brunt of 'energy'. With surface based CAPE (Convective Available Potential Energy) approaching 1000 units or more and temperatures in the mid-upper 70Fs inland showers/thunder possible in the orange zone most likely. Purple is where an even better chance exists, especially out over the Gulf Stream waters EAST of the Cape Canaveral area. On shore flow could 'exasperate' the rainfall potential from far Eastern Flagler  County southward to Martin County near the A1A corridor.    
There is a chance some heavier rainfall could occur along the SW Coast as well as the easterly low level flow stacks up against the mid-upper level westerlies. There is a large disagreement in early morning model guidance concerning that possibility.

Either way, the 'pool' of moisture as well as the 'energy' responsible for Monday's rain chance is all expected to pull off to the east before sunset although not entirely. Realizing that this post for today is based on data spit out at 2AM Sunday morning based on real-time information from 8pm (eastern) last night, much refinement as to timing and rain location details is desired, personally; however, based on the continuity between models this morning from previous runs, there has been little change since yesterday afternoon's results in model output...saying  something for consistency's sake.

BEYOND: There is a chance of showers and maybe some thunder on Tuesday interior and west side Central and South later in the afternoon, but elsewhere it will continue to warm toward the 80F mark each and everyday, particularly nearly statewide  by Thursday. There is no large significant 'drying' trend as far as clouds from time to time is concerned; thus, anyone anywhere could be in and out of some clouds from time to time, anytime. Wind will become southerly to eventually SSW-SW by Thursday/Friday time frame at which point east coast temperatures will possibly reach the mid 80Fs , and maybe more so depending on cloud coverage. The next frontal boundary poised for next weekend may not even make it beyond Central Florida if even the I-10 area. 

WINTER and OTHER CONCERNS?: In regard to cold temperatures, there has been no indication that any cold spell beyond One Day well into the first week of March is possible. Although it is too soon to say definitively so, we are reaching March at which time cold air intrusions seldom if ever pose a situation worth concern beyond one or two days, although cool periods can continue for quite some time to come.  

The other 'concern' will be in regard to Severe Weather. Although not necessarily for Florida, there will likely be at LEAST 3 Severe weather events to occur in the Deep South early this week through March 7th from Louisiana east and north through Mississippi/Alabama/part of Arkanasas/Tennessee and further eastward as well (other possible areas are possible in even more expansive coverage) . Whether Florida (any part of the state) will get into the 'action' is questionable, but not to completely disregard. March is often considered the "Severe Weather Month" (Severe Weather Awareness Week has already come and gone)...although the worst tornado outbreak in the State's History occurred in late February of 1998 nearly to the day.

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