"But seeing they could not See; hearing they could not Hear"
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"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".

Wednesday, March 9, 2011

Severe Weather Panhandle Today - Some Strong Central/South Thursday

This image shows storm reports yesterday through this morning. Note the reported tornadoes in NE Texas, as was being monitored in yesterday's post.  There has been innumerable tornado warnings since late yesterday, but comparatively near zero reports other than these noted above. The other biggest threat which has materialized has been flash flooding and strong winds. We can also see that a waterspout was observed by a pilot 15 miles east of Ft. Lauderdale. I also observed a suspicious looking shear funnel about 1 1/2 hours after the time of the Ft. Lauderdale waterspout very near the 520 Cswy. over the coast (Cocoa Beach) yesterday, dangling from the ill-defined base of a sprinkling ocean shower which was part of a covergence line.  It was hard to tell if it was an actual funnel or just a cloud filament, but for about 45 seconds it was very pronounced, and weak rotation seemed apparent. Also in this image, I've outlined an area in red in the panhandle where I'm monitoring for additional tornadic activity today. See more below in that regard.

TODAY: The storm system responsible for the flash flooding and flat out flooding in some areas as snow melt meets areas of prolonged heavy rains due to training storms down stream of the melt will continue today and expand NE ward into Tennessee, Kentucky, Virginas, and Pennsylvania.  The main line of overnight activity is passing through West Alabama as I type. Below is the current radar at 8AM EST. Wow, it's already in Central Alabama.  I've annotated in red the area to be watched today for tornadoes, although there exists a much broader area of 'potential' as well.

This line is moving quite steadily, considering just 3 hours ago it was passing over the Tuscaloosa area. Note the lagging portion over extreme Southern Mississippi. I've annotated on this radar image the main threat area to watch today through late afternoon. Latest guidance is indicating a strong 925mb wind 'streak' to move across this area from the south which will be undercutting strong jet stream level winds from the west during the time of peak heating (although heating will be greatly limited due to precedent cloud coverage). It'll all be about the sharply veering winds with height in the low levels that would be the prime instigator of potential tornadic activity here. As a matter of fact, as I'm typing a tornado watch was just issued to include the west half of my red/outlined area.

Over the remainder of the state today. Breezy and partly cloudy. East to ESE winds this morning should remain in the 12 -20mph with gusts to 28mph this afternoon, especially along the entire East Coast. Winds become more SE-SSE later this afternoon and remain elevated. Not looking for any rain through daylight hours, but will be watching for a sea breeze convergence line to form very close to Route 27 (30 miles either side of that line) late this afternoon as was referred to yesterday.  It will be warm and muggy today, particularly interior and west side of the state with highs in the low - mid 80s, with A1A temperatures north of Vero Beach in the mid-upper 70s up and down the coast, near 80F south of Ft. Pierce and coolest north of Brevard.

TONIGHT: It's now looking unlikely that these mainly low topped showers that form along Route 27 will be unable to latch on to the prevailing WSW steering flow higher up in the atmosphere above them, so not expecting them to make much eastward progress beyond Lake County to western Orange County, although a few could break loose and head toward NE Florida after 10pm. As winds become almost due south after 1AM, a separate area of coastal showers from near Boynton Beach to Daytona could ride up and along the immediate east coast as this will be a moist, long-fetched low level wind and nearly parallel to the warm Gulf Stream waters which are currently in place near the coast from Port St. Lucie and south which will advect directly NNW ward into the Cape Canaveral area. This would amount to a chance of a rain shower or two along and East of I-95.  Otherwise, the stronger activity associated directly with the storm system will be spreading east across the Panhandle, but appears will weaken substantially from Tallahassee and East as the stronger low level winds mentioned earlier lift northward and out of the main 'threat' area.

Overnight lows will be similar to those of last night, perhaps even warmer. Thus, overnight lows in the upper 60s to low 70s. Muggy with a S wind at 10-18mph.

THURSDAY: Storm system (rain), and our last shot at any real rain for quite some time to come, will be over most of North Central Florida at daybreak. The remainder of the state south of the Beach Line to south Tampa Bay should be dry right before sunrise, but this quickly changes with the first vestiges of sunlight.

Pre-frontal trough/confluence zone ahead of the cold front will be steadily marchinh ESE ward across Lake County at sunrise, with some stronger storms possible just before or at daybreak from the location toward Volusia/Flagler counties shown in 'blue' below.  

New resurgence of storms/showers emerges west of the Tampa Bay area and expands eastward during mid-morning.  Prefrontal trough to move across Central Florida between 9AM - 12:30pm with the heaviest of activity moving onshore the west coast, then weakening. Little heating of the day due to prevalent cloud cover will likely hinder strong storm develop initially, but expecting to see radar light up between 9:00 - 10:00AM with storms to the west developing and pressing east due to the fact that Central Florida will be in the left exit region of a departing jet stream max. Divergence aloft and horizontally rotating gyres aloft (vorticity) at various levels will increase shower/storm coverage  Activity with these rainshowers and some thunderstorms (some of which could be strong due to wind gusts of 40-48mph and pea to dime sized hail) now appears will have it's greatest impact in the secondary area bounded in blue below. 

This image is the general threat for thunderstorms tomorrow generated by the Storm Prediction Center (SPC). The blue lines are of my own making.  Will be mainly watch the east half of the state south of Vero Beach between the hours of 11:30AM - 2:30PM, as the stronger Gulf Storms will be crossing this portion of the state with potentially less early day cloud cover and thus more heating (leading to destabilization). Again, we see the other area further north due to pre-sunrise activity  area noted just north of Brevard to watch for a strong storm more directly related to the synoptic scale wind fields, not due to destabilization.  

We can see from this image that much of immediate Central Florida 'could' be slotted from any threatening weather conditions, but this could change EASILY after events unfold later today and tonight.  The areas shown below are merely based on overall synoptic scale forecasts generated at 1AM this morning and not on mesoscale features that develop once initial activity has commenced.  Probably most everyone will received rain between later tonight and sunset Thursday, varying from a trace to 1/2 inch, maybe even a 1" total somewhere. Storms will be moving at 20-30mph, so the heaviest of activity won't linger long enough for larger rainfall totals.

So when does the rain end? Again, per guidance (which is in close agreement), the actual cold front will be across Central Florida at sunset with indications that the atmosphere will remain quite moist and 'stirred up' even after passage of the confluent/ pre-frontal activity earlier in the late morning/early afternoon. With that, there is a chance of an isolated rain shower South Central / South Florida until sunset, but completely gone shortly thereafter.

FRIDAY-WEEKEND: Very cool to cold, especially since it's been quite some time since much of Florida (other than NW Florida) has had winter like air in this region. So the bark could hurt more than reality.  Cold air advection/infiltration will be in full swing all night Thursday night and all of Friday.  Morning lows Friday in the mid-40s inland, upper 40Fs near the coast. Afternoon highs I'm tempted to leave in the lower - mid 60s on Friday due to continued cold air infiltration. However, given the time of year and higher sun angle (as opposed to early January), this could translate to upper 60s and quite breezy from the NW. Dry (which is not good as Fire Weather threat will start to be an increasing problem from this point on).

SATURDAY/SUNDAY: A cold morning with some lows in the upper 30s northern portions of North Central, with more mid-upper 40s interior down to SW Florida and on the north side of the Big Lake.  Cold air advection will have ceased though, so winds should relax more with highs reaching the lower to mid 70s South (and hoping this is not wishful thinking in regards to how warm it will be).  Sunday will be another cold morning in the interior, but gradual warm up along the coasts overnight begins.

MONDAY-WEDNESDAY: Continued very gradual warm up, with temperatures returning to seasonable norms (highs in the mid-upper 70s) by Wednesday. No chance of rain at this point, and don't see any arriving anytime soon.

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