"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".

Tuesday, June 7, 2011

Chance of Thunder in North Florida/Panhandle, Small Chance Portions of North Central

Shown: Mock radar composite reflectivity (what radar would look like) at 9:15AM this morning. The area off the Florida East Coast is relatively accurate. This area is moving slowly toward the wwst to WSW this morning, whereas the areas of 'showers' depicted elsewhere do not exist. Details in text below.

TODAY: High pressure in the mid-upper levels remains over the Deep South and Florida. Showers (with some lightning per lightning imagery) seems to be related to a weak mid-level disturbance embedded around the main clockwise circulation around the periphery of these high pressure 'centers', per se.

Otherwise, the clockwise circulation is bringing full easterly flow across Peninsular Florida, but it is weaker over North Florida closer to the center of the high pressure areas.  With this factor considered, for today it currently seems feasible to believe that a Gulf Coast Sea Breeze will be able to establish over the Panhandle and a portion of far North Central Florida (west of Gainesville) where thunderstorms will be most apt to be able to develop. This same region is also forecast by all guidance to have the most unstable air conducive for storm development. It does not appear that a west coast sea breeze will be able to develop further south, or if so, it would be so close to the coast in a more stable air mass (namely south of Brooksville) that thunder or even showers would be able to develop there as a result of a sea breeze/Lake Breeze collsion.

Meanwhile (and additionally), the best low-mid level moisture going into mid-afternoon is forecast to exist outside of the most unstable air to the north...which does not really make sense considering that moist air is more buoyant.   However, taking the forecast moisture fields into account, as well as having viewed visible satellite imagery the past two hours, it would not be entirely infeasible to consider that rain showers could reach the Florida North Central Coastal communities by mid-afternoon toward Flagler County and eventually southward with time toward far North Brevard county.  The Flagler option seems most plausible at this time; further south, it  will be a race with time considering that Convective Inhibition is forecast to expand northward from South Florida toward the Cape area by 7pm.  With those factors in mind, we cannot entirely discount the chance that some of those offshore showers might impede upon the coast by early-mid afternoon as far south as Volusia County as thunder or even North Brevard as showers later today.  

Further south in Southern Volusia/North Brevard, not so sure the activity will even be 'surface based', especially since model guidance indicates the activity is associated with a mid-level trough around 700mb (10,000 ft) rather than a surface trough. Again, with that factor in mind, the Cape area north of the 520 Cswy might see a few drops of rain before the sun has set late today (North Brevard).  

Keep in mind, any minor deviation in the ebb and flow during the day today could either:

 A) totally preclude rain chances at all along the east coast. This would be due to the fact that the easterly gradient flow combined with the east coast sea breeze (which is forecast to pick up to 15-22mph this afternoon) would squelch the activity currently offshore as it approaches the coast due to subsiding (sinking) air behind the sea breeze, leaving it as only elevated 'junk' clouds; or, 

 B) increase the thunder chance further south toward the 520 CSWY; or

 C) per model guidance on average  as currently portrayed by some models, bring a certain chance of at least rain with a few rumbles into Flagler and Volusia Counties with measurable rain by 3-4pm.

Elsewhere, no rain is expected to occur over South Central or South Florida today.

BEYOND: Little change in the mid-long range models, as well as with the feisty NAM. Again, the NAM is forecasting an inverted trough, and even a bit of a close low-mid level area of low pressure to press northward during the next 42-84 hours into Florida. The net effect is a band of precipitation moving northward with time from South Florida and into Central Florida before the weekend. Again, I'm discarding it; but watching with care. The ECMWF (European Model)...seems to indicate a similar scenario but the information I have over the internet without using a 'pay service' does not provide the finer details. 

Meanwhile, the GFS holds firm to its previous idea from 3 days ago, with only minor deviations in timing and pressure system locations. That being, once the jet stream level winds which are currently suppressing tropical development in the SW Caribbean shift east of Florida, this permits either an inverted trough or a  weak low pressure center to move into the Eastern GOM (Gulf of Mexico) west of the peninsula going into early next week.  This would increase the moisture levels over all of the state and completely change the low-mid-upper level wind fields across the state, favoring the east side for diurnal afternoon rain/thunderstorm chances in only a slight/moderate unstable atmospheric thermal profile. In other words, late week through next week are still up for grabs... but I'm tending to favor the GFS considering how consistent it has been...and hoping for the needed rainfall over South Florida optimistically (and admittedly, wishfully).

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