"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".

Friday, June 18, 2010

Tricky Thunderstorm Forecast Again Today

(Image: Wall Cloud over West Cocoa)

Yesterday's atmosphere yielded some isolated but hefty thunder boomers, and two severe thunderstorm warnings were issued for the general area of East Central Florida (Holopaw and Titusville). Storms showed very little motion although there was a general eastward drift in some pockets which allowed activity to reach the coast along the southern tier of Brevard, northern Volusia, and near Ft Pierce. Overall though, as anticipated, motion/propogation was dictated by sea/lake/out-flow boundary interactions.

A few minute differences at this time this morning from yesterday might be worth mentioning. Number one. The morning sounding from KSC showed an increase in the PWAT value. This probably means very little to the overall outcome of things other than that it confirms the existence of abundant moisture at all atmospheric levels. The water vapor imagery shows a shrunken 'drier air' area from yesterday over Brevard, but this played little into the overall scheme of things yesterday and expect this will be the case for today as well. Also, winds aloft this morning were even lighter (if that's possible) than yesterday with not much more than a 7 kt puff the whole way up to 30,000 feet. Indicative once again of the type of storm motion we will have today. Interestingly, activity in the Gulf this morning has gotten off to an early start and there's already some showers around the Tampa area. Again, not sure if this will have any bearing on the weather outcome for East Central Florida this afternoon as the Gulf activity is showing zero motion. The last item of note is that there appears to be a weak surface boundary extending from SW to NE from basically just south of Sarasota to just north of Daytona Beach (similar to the position of yesterday morning's surface boundary).

Expect east coast sea breeze to kick-in between 12:30-1:30pm in its entirety along the coast, but believe the west coast boundary will kick in sooner and initially be more active . Some activity may pop initially along the east coast sea-breeze as well, particularly along Volusia and extreme N. Brevard as it pushes inland, but not nearly as active as the west coast one will be. The initial east coast activity should only have the generic impacts of getting one wet with a few lightning strikes. The real activity won't get started in earnest until between 2-3pm after day time heating has allowed lake, sea, and initial convective/collapsed activity breezes to work against each other in a variety of ways establishing localized pockets of low level convergence (and hence upward vertical motion). If the west coast sea-breeze is indeed more active today than usual, storms could be enhanced as we look toward Osceola and Orange counties going into the mid-late afternoon hours, so this will be something to watch for.

Finding a 'most likely area of activity' today is close to impossible...but believe after all is said and done that things will evolve 'similar' to yesterday (and I say similar because no two days are exactly alike, so variations in storm evolution are inevitable). There are no sig pockets detectable of cold temperatures aloft or triggering mechanisms in storm intensity will likely be the same as yesterday without that added instability ingredient, but a possible severe warning or two could be issued somewhere across the area.

As for the east coast today, with the slight increase of moisture indicated by the KSC sounding, and based on the latest LDIS upper level/steering currents plot...the chances appear at this time to be a little higher for the immediate coast to at least experience some rain today, but the greatest likelihood of the big storms will still be west of I-95 or perhaps US-1. However, if the west coast boundary does evolve early and really get going it tends to be 'self perpetuating' (enhanced)...thus, outflow boundaries could give the storms that additional boost needed to work their way against the east coast seabreeze and propogate closer to the coast.

Current thinking is for the final show being from Western Volusia and all of Seminole Counties eventually working south toward N. Okeechobee County. Not to leave out Osceola County where activity there should spread in from the North and West from 3:oopm onward. Then, as noted before, it'll be a wait and see game as to just exactly which activity can penetrate to the immediate coastal communities.

Saturday now appears that it will display more activity coverage wise than today. Sunday will again be active across the region but a decline is on the horizon. If we can squeeze it out, Monday would be the last gasp for the rest of the week as far as afternoon thunderstorms along the east 1/4 of the state.

Still watching for early morning, coastal shower activity to potentially show its face beginning Wednesday, making for some pretty awesome sunrises.

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