"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, September 28, 2010

POST 1: Tropical Storm Develop Much More Likely - Rotating Storm Structures for East Central Florida?

(Image: Total Rainfall forecast for 2am - 8am Wednesday shows max over Brevard County and SE Florida)
OBSERVATION ONLY: Breaking down the details very early this Tuesday and monitoring trends in RUC Model updates.
The current observation is noted. Surface front extends from Jacksonville to Tampa. Mid-upper level support for this feature has moved NNE from Alabama yesterday to West Virginia and continues north toward NW Pennsylvania. Likewise, vorticity maxima are plunging south down the backside of the trough through Wisconsin prior to sunrise with expectation this energy will penetrate as far south as Southern Alabama by early Wednesday morning. The result will be to reinforce the the mid-level trough in its current position and thus prevent further eastward progression of the surface front as its southern tip skims close to North Brevard and then becomes cut off as cyclonic circulation from the south takes the leading role. Meanwhile, Central Florida will be influenced by negative vorticity advection early on this Tuesday morning during the following transition:
1) Area of low pressure with a 60 percent chance of becoming a closed surface circulation over the Western Caribbean and its  peripheral circulation begins to drift north toward Cuba. ***UPDATE: This has just changed to 80 percent***. We could have a Nicole on our hands by the next update from the Hurricane Center. But I digress,
South Florida was never affected by the trough and front, and thus have been in continuous ESE-SE flow all along, unlike folks from Central Florida and points north. Current water vapor loops and surface observations indicate that South Central and Central Florida will be encompassed with the low level circulatory pattern between 11am-1pm today directly related to the developing system to the south. Meaning, surface winds will shift from SSW-S to a more SE-ESE component. Meanwhile,  the mid-upper level features described above reinforce the wind aloft at those levels maintaining the current SW direction overhead.
2) Transition of these two wind field parameters occurs primarily between 11am -4pm during the time of maximum surface heating, although cloud cover could be a big factor in damping out the overall convective nature of shower activity from what could otherwise be a more potent situation. During this time frame, as the outer parameter of the cyclonic circulation from the south enters Central Florida, positive vorticity advection is ushered in from the south.
The combination of low and upper level vorticity, low level directional wind shear, and influx of even greater moisture from what currently exists could harbor resultant rapidly developing small, but rotating storm cells. The affect will be maximized along the East Coast from Sebastian Inlet to Ormond Beach.
Believe the main affect of this, should it occur, would be strong, gusty winds associated with fast moving, small thunderstorms...but circulations reaching the ground can't be ruled out. This covers Tuesday afternoon, now what about over night tonight?
AFTER MIDNIGHT: The NAM and GFS continue to support the first vorticity maximum directly related to the Tropical System (by this time Nicole?) to impact Indian River, Brevard, and Volusia County between the hours of 1am - 9am Wednesday morning as further development continues. As noted, by this time we might have a named system which would add fuel to the fire. The HPC has forecast a precipitation bulls eye for mostly Brevard County during this time frame of over 1" of rain, so they must be seeing something. Believe this rainfall will come in the form of convective storms containing brief periods of heavy rain rather than a solid, steady state rain. Conditions do not look as ideal as yesterday morning for rotating storm cell structures, but should the system approaching from the south indeed wrap up as much or more than anticipated the weather radios might be blaring with Special Weather Statements or warnings while most folks are in bed.
SPECIAL NOTE: Should Invest 96L develop into a named system, the timing on the over night situation tonight might still occur, but could be a full 12 hours later, at least, than current thinking. Thus, this could take place  during the afternoon on Wednesday. Additionally, note that this is not information from official resources. Namely, I'm thinking out loud. Just providing a heads up.
P.S.: Should the system to the south develop into a named system and strengthen toward hurricane intensity, all forecasts for the state will be blown out of the water as far as wind speeds and precipitation coverage are concerned. Based on track forecasts from multiple models I've flipped thru this morning, should a system develop, the tracks are most clustered from South of Naples toward West Palm Beach, with 2 or 3 others going as far north as New Smyrna Beach on the East Coast. (opting out the other tracks taking the system toward Texas for now...but that possibility has been indicated).

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