"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, December 10, 2012

A Strong to Severe Storm Potential Exists Today - Otherwise, Rain Seems Likely

Latest visible satellite Imagery shows storms over the Gulf progressing ENE-ward toward mainly Central Florida. Although that activity will not hold together per se as a unit, the 'energy' causing them should be crossing parts of North Central to South Central after 2-3 pm today with rapid changes forthcoming if that is indeed to be the case
TODAY: Changes already in place today with a southerly, long-awaited  wind directional component. It has been quite some time since there has been  southerly to southwest winds across the state, where easterlies to northerlies have been predominant since early November. As such and as noted yesterday, moisture is expected in increase rapidly by mid afternoon across Central across the boards around the outer periphery of the surface ridge axis which appears will remain across far South Florida one more day (which might off set storm potential in that area).

Otherwise, I've ignored the NAM model as it did not initialize well at all from this perspective of current activity on satellite imagery (above). The GFS and RAP (former RUC) are both showing several low to mid-level 'swirls' of vorticity (energy) to be in place across Central later today, with the GFS showing vertical velocities up through the 18,000 foot level over Dead Central from mid afternoon through early evening. As such, and if that holds true, then some rainfall totals of up to 2,00' could occur in and near the red zone. The biggest issue in that determination is whether or not high clouds streaming eastward from the initial activity to the west will offset (or 'seed')   downstream activity ahead of the west to east storm motions anticipated. Which means, clouds could stabilize the atmosphere and off set storm potential.

On the other hand, the KSC sounding shows respectable turning of height with winds, and the Energy helicity index which compounds helicity with unstable overall atmospheric conditions measured in CAPE *(convective available potential energy) coupled with continued influx of that parameter from the south under any cloud canopy could result in strong to severe storms regardless. So for all purposes in the blog post, will throw this in although no official outlet such as the Storm Prediction Center or The National Weather Service is stating such. Just never know. Otherwise, there is a potential for some unusual for this time of year rainfall to occur across mainly the red/ and / or but not all inclusive orange zone in the image above.

BEYOND: Tuesday and Wednesday get dicey. The SPC has already placed Central in a potential for severe weather on Tuesday as noted. There will likely be timing issues combined with reboot, destabilization requirements after today's activity regardless of which form it takes,  which might need to be resolved after today's anticipated activity. Chances are it will all be continent upon a vorticity max crossing over on Tuesday (upper level energy when stated generically), regardless of other situational atmospheric circumstances. 

This forecast pictured below was formulated around 1 AM last night, and will likely be updated by the time this post is completed, as it is scheduled to be by 12:30PM EST today. (* SPC just updated and maintains this zone shown for tomorrow).

Outside of any severe potential either today or Tuesday the bigger story is rainfall potential accompanied by rather strong wind gusts regardless of whether the heavier rain is being generated by a thunderstorm (or not). 

Any storms to arrive today, do note, will not necessarily be 'easily observable upon approach' except perhaps the first activity of the day, but could be buried in cloud cover, with only a darkening toward the westerly direction as the activity gets close to one's proximity. So, if you have a good radar source on line or on TV and plan to head out, now might be a good period of days to accommodate them.

The GFS and to some degree the latest RAP model run are showing rainfall exceeding 1" today particularly over the Barrier Islands for a reason unknown; that has been the trend now in successive model runs over the past 24 hours as well. In any case, here is an 'example' image of total rainfall between today and when the show is over sometime later Wednesday.

Note the purple which would indicate at least 3" of rain over
East Brevard and Indian River Counties. I cannot really see any sound
basis for selecting that area, but the GFS insists. Perhaps it is using  data points of MLB and KSC
being ingested into the model as a framework of determination.
THURSDAY: Up until Thursday, a frontal boundary appears will be 'somewhere' across parts of Central, possibly wavering south then back north  then back south..from Tuesday evening if not before . This means more disturbances riding along the boundary could result in more storms, rains, or merely cloud coverage; nothing is set in stone other-than rain chances are high with emphasis on 'chances'.

By Friday the frontal activity should have cleared as onshore flow quickly replaces said activity  and temperatures will return to much of what we experienced earlier this week, with stratocumulus clouds and possible quick spits of light rain near the coast for a day or two. Could be a bit breezy along the coast as well for a few days, but nothing unusual as lows return to the mid-upper 60Fs and highs in the low-mid 70Fs prevailing near the coast, cooler inland over night.

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