"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".

Thursday, July 1, 2010

Big Change Overnight Could Manifest as Storms Today

(Image: Hurricane Alex makes landfall)
Some pretty big changes have occurred overnight which could manifest as higher storm coverage today over the immediate area. This change first became evident last night from an observer's point of view when an outflow boundary just above ground level from an inland storm (manifested by a linear cloud deck) passed over Cape Canaveral at 7pm. It's been nearly 2 weeks since we've even seen an outflow boundary reach the immediate coast so I was eager to see what the morning sounding was showing. It is worth mentioning that believe it or not it hasn't been dry everywhere in the state by any means. There has been storms, particularly yesterday, all over the west half of the state the past few days...but you'd never know it without looking at radar or having a trained eye to see the storms from a distance.

Sure enough...the big changes are in the mid levels where two things stand out immediately: (1) The temperature at this level has dropped by nearly 5 degrees since yesterday; and (2) Moisture has greatly increased in this level. Total PWAT has increased throughout the column from yesterday as well. Additionally, the wind at this level, although very light (less than 10 kts) predominantly from a westerly component which is backed up by area profilers showing a westerly wind component beginning around 6000 ft (southerly below that).

Two other factors in play for today which have been referred to in earlier posts: (1) The TUTT low that was in the North/Central Bahamas has made a marked drop to the SSW and is now over Central Cuba in a much weakened state. The subsidence/dry slot around the NW periphery of this system could be a big negative for even better rain chances today though. Latest water vapor loops show that perhaps some drying in the mid-levels has worked into the south half of Brevard and all points south toward Miami in the past 2 hours (after the KSC sounding was launched). The drying seems to be working further west and north...but just how much this continues might be determined by factor number 2. (2) The mid-latitudinal trough...which also exists mainly at the mid-levels has made its way into the Florida panhandle and at this point will probably start to lay out in a more west-east orientation south of I-10 and reside this afternoon somewhere between I-10 and Ocala by late afternoon.

Maybe not so ironically, this is the same area that the level of apparent drying from the TUTT could reach which could result in a wonderful moisture gradient for the atmosphere to work on by late afternoon. The very fact that mid-level temps have dropped so much and moisture gone up at this level over the Space Center this morning proves its very existence near by. This trough will likely be the primary initial threat area for clouds/storms today before things get crazy over the remainder of the peninsula with day time heating. Cloud coverage this morning as of 9am is basically non-existent over the region other than some patchy high heating and increased instability won't be a problem to set the wheels in motion by late morning. Just what happens from there will be interesting.

Given all of the above, it might be worth a trip into Osceola County today or maybe even closer to home toward the Indian River for some storm photo-ops...but in cases like today (just like any decent Florida storm day along the east coast) things will start to fall into the "watch on an hourly basis before making any commitments" category.

The main thing to watch today will be those mid-level winds and temperatures in later KSC soundings. I wish I could be making this post later in the morning toward noon time since by that time we'll have a better grip on how this afternoon will evolve...but then that would be more of a NOWcast rather than a FOREcast.

A lot will hinge today on what happens with the impinging subsidence associated with the remnant TUTT low and the extent of its influence down to the immediate local level.

Things to watch for today will be the possiblity of early convection onset (after 10:30-11am) close to the Indian River. With the mid-level temperatures having dropped so much and moisture increased this currently appears to be a good possibility. If it does get going, then a funnel cloud might not be out of the question along the leading edge of the sea breeze over the rivers. Expect storms to go up over Osceola County along the Florida Turnpike, Orange, Seminole, Western Volusia, and Okeehobee Counties by mid-late afternoon. Bascially, every where one would normally expect to have them.

After today a lot depends on what happens with an area of strong high pressure building across the mid-west and into the Northeast states. The NAM indicates that it will have no problem totally engulfing the entire east half of the U.S., including Florida, which would put most if not all of Florida in a drier, easterly flow and nearly rain free regime. On the other hand, the GFS continues its 'wet' scenario...keeping the mid-level trough across the Central Florida within an atmospheric pool of moisture and stormy conditions for every afternoon into the beginning of next week. It has also continued to depict spurious blobs of rainfall almost anywhere along the trough axis from Louisiana east to off the Florida east coast. It has been insistent on this scenario for days. Given the time of year I am more inclined to go with the lighter side of the GFS depiction...which would mean not a full blown "high pressure from the North take-over"...but not a total wash out either. But no matter which model verifies, at this time it looks like the best chance for the east central Florida coast to see some rain will be today and tomorrow. By that time hopefully things will look promising for continued better chances. We could use it.

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