"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".

Sunday, August 22, 2010

Boundary/Sea Breeze Front Collision Convection Day In Store

Image: Looking west across the Banana River toward US1 at storms that lined up along the US1-I95 Corridor yesterday. This image shows the outflow developed gust front that moved across the A1A corridor associated with those storms to the west. Also of note, anvil level winds steering storm tops away from the coast, keeping the sky blue until the storm is nearly right on top of any affected area.
RECAP: After posting yesterday morning it became apparent that East Central Florida had drawn the Tarot Card with an umbrella on it from the deck. It was mentioned that early morning convection was on going over West Central Florida to near the Lake County Area. The convection never made it further east as was suspected and in fact these storms eventually collapsed and scoured out much of West Central Florida; however, once we had some daytime heating and a cumulus cloud field formed it was easily apparent through watching the visible satellite imagery animation that a great outflow boundary from that collapsed convection was spreading rapidly ESE across the peninsula. As it progressed across the state the east coast was sitting pretty with the normal noon time sea breeze beginning to slowly develop. Some good cloud lines initially developed over the Space Center south over Cape Canaveral but nothing came out of this activity. Once the sea breeze developed in earnest which was by 1pm these clouds dissipated and further development along its leading edge to the west. Steering currents were weakly from the north the sea breeze took its time working west across the rivers and made it about as far west as somewhere between US1 or I-95. Meanwhile, the aforementioned outflow continued through the Orlando area and met the sea breeze right along that corridor. As such, storms rapidly developed in a North/South line the entire length of Brevard County beginning around 1:30pm dumping over 2" of rain over many areas. With the steering currents nearly paralleling the coast this activity was hard pressed to cross the waterways in earnest. As a result, rainfall totals were significantly lower out on the barrier islands, although the entire spectacle was fun to watch out there at a 'safe' distance from the lightning (see image included in this post).
SYNOPSIS:  As of 9am it appears that East Central Florida is in somewhat of a mid level COL with low pressure over the mid-Atlantic to the NE states and well to the south of the state. At the same time high pressure is well off the east coast with another area extending into the Gulf from a core right over the Central U.S. states.  The Central and Southern Peninsula in general are not being directly affected by any of these features this morning. As such, surface winds are land breeze generated and winds aloft are all less than 10 kts, but generally from the north. The area most in this indefinable wind field predicament appears to be, of all places, Brevard and Indian River Counties. I haven't been able to obtain a sounding from KSC for two days now, at least not before making a blog post. Yesterday's finally came out well after the post, but even so probably would have been of little use considering the circumstances that developed. Given water vapor imagery though and current forecast trends, see no reason that there is not abundant atmospheric moisture to work with again today coupled with the standard warmer than normal mid-upper level temperatures.
NEAR TERM SYNOPTIC FORECAST:  Based on model trends/forecasts for the past 2 days and continuity believe that much of the peninsula will eventually be under a very broad mid-level area of low pressure at the base of the trough now running down the U.S. eastern seaboard through the NE and mid-Atlantic states by day's end during the course of the day. As such, a trough axis will eventually develop which at this time appears will be running from near Daytona Beach SW to just south of Sarasota by mid-day Monday...after which a very discernible steering flow will be established.  Steering currents today will remain very very weak to non-existent in the meantime, with a NE wind at the upper most limit aloft of the steering current level. Anvil level winds will remain from the NE as they have for days. But until then...
TODAY: With the scenario painted out 'as such' above, the local forecast for much of East Central Florida and much of South Florida is quite the quandary at this time of day with no synoptic scale features at hand to work with. Will the same thing happen today as yesterday?  Highly unlikely. There was a lot of storm activity along the west coast this morning over Tampa and points south like yesterday, but this activity is moving generally toward the SSW (off their coast over there) and has pretty much all but ended now for that entire region. More will be revealed once cumulus clouds start to form in earnest, but that is still another hour from now. As such:
Expect east coast sea breeze to once again form on queue between 12:00-1:00pm. It should be slow to migrate west once again with no help from upper level winds to either enhance it nor pin it on the coast either.  With ample moisture around...and perhaps even more at the low levels once the sun gets beating under nearly clear skies due to transevaporation/transpiration from already rain soaked grounds...the cumulus field will start to develop most noticeably after the thin land strips of the Space Center, near larger inland lakes, and along the shores of the intracoastal as early as 10am. As these clouds gain a little substance and merge rain showers will eventually form just about anywhere with very little motion. Clouds will grow most formidably along the developing, light sea breeze and move very little. It will be interesting to see what the west coast sea breeze does today, especially after all the rain shower activity they've had over there this we'll have to be watching that.
Wherever, showers and perhaps some lightning develops during the 10am-3pm time frame..they should remain fairly isolated without broad 'expansial' coverage. With additional heating of the day the atmosphere over the peninsula will become increasingly unstable and rising thermals will give way to further cumulus cloud development over the entire peninsula except behind the sea breeze. I'm going to watching the KSC toward the port though. With almost no winds aloft and rapid rising thermals...who knows.
Once we reach the mid-late afternoon just about anywhere could get a storm as boundary collisions occur from collapsing earlier activity and peak instability is reached. Toward evening, as the mid-level trough axis becomes established a bit of a push toward the east will be develop mainly south of Daytona Beach-Miami.
ENOUGH FOR TODAY: In short, Monday-Tuesday look to be days with enhanced flow from the SSW-SW with showers/storms most likely in the afternoons/evenings on the east side of the state south of Flagler and perhaps most of Volusia well as early morning activity around Tampa Bay.
WEDNESDAY-THURSDAY: Transitioning back to more of normal wind field pattern as mid-level gradient flow relaxes.
BEYOND: Thunderstorm shut down. Dryer, stacked easterly flow becomes established as high pressure builds eastward from the Central U.S. states over the mid-Atlantic region and off shore that region.

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