"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, June 20, 2010

Active Thunderstorm Day A-'Brewin'

(Image: Distant thunderhead over Palm Bay in South Brevard yesterday)

Several atmospheric differences today which should enhance the potential for afternoon thunderstorms across the Central Florida Peninsula. Although yesterday was quiet per se across the Central part of the state it did eventually light up in the evening with a 3/4" hail report in the Orlando area. Most of the activity didn't really get going though until well after dark. Do not believe this will be the case today. At least not as of 9am this morning.

Today: A number of things jump out immediately:

#1: There appears to be a remnant outflow boundary (or mid-level 'wave') that's progressed steadily south down through the Deep South since yesterday per water vapor/satellite loops and surface observations. That boundary is now situated from near St. Augustine on the east coast to near Crystal River on the west coast. Further to the north and east...this boundary appears to be connected to, and associated with, a cluster of shower activity off the Carolina coast. It seems to have slowed its southward push over the land mass...but is continuing south over the Gulf. Looks like it might get hung up along I-4 or just south and east of this bears watching.

#2: Like Friday morning, there is more early morning activity over the Gulf and a little along the Atlantic coast from near Miami toward West Palm Beach. Most of the activity is nearly stationary though. This activity was absent on Saturday. Expect this activity to slowly creep up the coast in the late morning and very early afternoon hours.

#3: Morning instability (convective indices) per the KSC sounding and LDIS plots is already becoming evident at 8-9am. Especially in the area yesterday where there was 'relatively' little indicated all day as compared to other days this past week (over Central Florida).

#4: Winds aloft per the KSC sounding, although very light, are showing a west-east direction the whole way up to nearly 500mb. Although they are generally less than 10kts...the fact that the direction is pretty much uniform all the way up indicates to me that the boundary that has moved into N. Florida is indicative of possibly more than what that the models (from last night) are alluding to at this time. The latest RUC model seems to have a clue as to what is going on though...which is encouraging. Also, averaged winds through the mid-levels are showing cyclonic circulation along the coast near Crystal River (which would correlate with the boundary mentioned earlier). The steering currents depict a broad swath of SW flow across all of Central Florida...whereas yesterday morning the winds were totally disorganized and all over the place).

#5: The sounding does not show much change in the PWAT value this morning from yesterday...but higher PWAT is forecast by this afternoon. This would coincide with the remnants of the boundary to the north sinking into the Central Peninsula. The convective temperature on the sounding has come down a few degrees from this time yesterday. At this time yesterday it was 94, whereas today it is only 90 which is totally reachable over the Cape.

#6: The dry area that has been perpetually in place across extreme East Central Florida (namely over all of Brevard and parts of counties to the north and south) on the water vapor imagery has almost completely eroded away...but not entirely. I think this is why the sounding at KSC is still 'drier' than surrounding areas...but the area has shrunk so much that it will take very little to be eroded away.

Now, further to the south from St. Lucie County and points south almost nothing has changed much. An over all on-shore component is already yielding the 'close to the coast/early in the day' activity which will progressively work its way west and north during the day...and set off a boundary which will work up the peninsula much like yesterday. In fact, there's already a shower near West Palm Beach and another just off the coast of Fort Pierce at this hour.

When push comes to shove, it looks like there could be some good storm coverage along the I-4 corridor today pretty much almost anywhere. Like other days, the coast east of US-1 or I-95 will have a hard time seeing anything north of Indian River County, although I wouldn't be surprised to see outflow of sorts in the form of a remnant gust front (unaccompanied by rain) to reach the coast between 6-8pm along with a cooling wind shift. However, I do expect some strong storms today, no matter where they may (particularly after 4pm and inland), mostly due to wet microburst winds and sub-severe sized hail.

The fly in ointment today will be to see if activity will hold off for the most part until at least 3pm. If it gets going too soon and spreads out too broadly than the atmosphere will be worked over before it can reach the maximum level of potential instability..and thus more vigorous storm intensity.

After today, the show will likely be over as far as good thunderstorms goes for the east 1/2 of the state. So enjoy a light show if you can get one today...lets get one for dear old Dad.

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