"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".

Monday, July 25, 2011

Isolated Late Afternoon - Mid Evening Thunder Possible

CURRENT CONDITIONS: This shows very unfavorable conditions for storms to form over Central Florida as of noon. ..the blue area. This area has been slowly eroding since early morning. Also shown is some stronger thunder along the Big Bend moving east around 10 mph.  The seabreeze has not yet formed north of Vero Beach but probably will shortly. Cloud cover along the east coast is being exasperated by upper level divergence associated with a TUTT low off the East coast of Florida. This is also creating sinking air, creating more forecast issues for today in regard to anything beyond rain showers. Otherwise, the atmosphere is unstable with ample moisture between 1.7" - 2.0" of PWAT, mostly north of the northern blue line

TRANSITION DAY - CURRENT: The atmosphere is unstable today with sufficient moisture for scattered storm activity. But there is a problem. A TUTT low (tropical upper level tropospheric trough) is located off the Florida East coast. Circulation on the descending air side of the low has spread across eastern Central and starting to reach SE Florida in NE winds aloft (at jet stream level). This low is not forecast to move much today. In that regard, I am tempted to say, NO THUNDER today over Central least not until after 8pm. However, model guidance insists on showing rainshower activity...and that might very well be all that will occur today..with a renegade thunder chance central. Most likely Thunder will occur over North Florida from its current location toward Flagler County, as well as over SW Florida and close to Lake Okeechobee. Things could change during mid-afternoon. In fact, today is a TRANSITION DAY from the past two days.

The transition is that a mid-upper level trough and frontal boundary, which will never make it to Florida, is beginning to dig down the East coast just offshore in the upper levels and more toward the west in the mid-levels. During the transition the ridge axis is slowly sinking south piece meal. There is a number of things going on  today, but it is so convoluted, slow, and disorganized in doing so that it is difficult to put a finger on anything.  This leaves to resorting to the summer norm of relying on Lake and Sea Breezes for iniation in areas where conditions are favorable otherwise which is acorss North Florida and Near Lake Okeechobee through mid Afternoon.

This is the latest satellite image. Mid-high clouds are continuously forming on the back side of the TUTT low off the east coast. These are spreading SSW toward Lake Okeechobee. WHOOPS. Maybe that area isn't so favorable for development afterall. The air down that way is also most dry.. This leaves us with North Florida through at least the first half of the afternoon

TODAY: With so many unfavorable parameters in play being 1) A cap still in place at 1pm ( 2) warm air in the mid levels with 700mb coming in at 10C (3) Cloud cover over Lake Okeechobee 4)Sinking air behind the offshore is easier to argue for no thunder rather than for it..other than over North Florida which is experiencing none of the negative factors 5) Delayed Seabreeze likely leading to no sea breeze collision other than over SW and NE Florida (like yesterday). I have drawn in a wishful thinking area for rain and thunder activity today for Central, but the entire area encompassing Central Florida is pure speculation, and not applicable, if ever, until after 4pm lasting through 9pm.

Green is where an isolated shower could from, orange isolated thunder, and red some stronger thunder (any of which would be brief except maybe North Florida).

Why it could rain or thunder Central: As noted, today is a transition day. Often these transitions happen either slower or faster than anticipated. In the case of today's sketched in precipitation, that was opting on the faster side, although as of 1pm  I'm not seeing it happen. Essentially, the make or break point is going to occur between 2-4pm when Lake Breezes and sea breezes have formed and are underway. It will depend on the air mass above those breezes and where/when they meet and what the air mass above those areas is like that will determine the rain chance later today. There is the remote chance that some of the instability will remain bottled up until after dark, at which point a storm could form very close to the East Coast from Daytona to Vero Beach. These events are nearly never forecast though by guidance..and given the warm mid-level temperatures not expected to change much..the atmosphere would not be all so conducive. Best chance for a dusk toward 10pm storm would be close to the east coast and in toward Osceola County.

TUESDAY/WEDNESDAY: There has been references to a tropical wave. This wave is to pass well south of Florida, so the only conclusive evidence I've can squeeze out for it to aid in rain chances would be some moisture being advected northward from it as it gets just SSW of the state overnight tonight in deeper SW flow at the surface and aloft. This could also begin as soon as early evening, which gives one more reason to rationalize a late evening storm somewhere, since new, incoming moisture often results in a storm during a transition.

Otherwise, warmer days beachside are in store, esp. on Tuesday with a delayed sea breeze. Increased cloud cover should offset the inland temperatures from rising above that of past days though. Not sure there will even be a seabreeze north of Port Canaveral on Tuesday, which would mean mostly showers north of that location, possibly forming into thunder as they move offshore.  Late afternoon intracoastal upwind factor could play in, for storms close to the coast of Brevard/Southern Volusia County though...with other storms favoring the east side of the state south to Boyton Beach...with widespread shower and storm activity otherwise by mid-late afternoon mainly on the east 1/2 of the state.

WEDNESDAY: We will start to transition out of Tuesday's hard set pattern just a bit by mid afternoon. This should allow sea breezes to form all along the east coast with more widespread thunder chances with cooler mid-level temperatures with a sea breeze collision from both coasts. Activity might initiate too early in the afternoon for other than very isolated stronger storms...but we'll just have to wait and see how things play out in regard to cloud cover, speed of sea breeze initiation, and which one plays out to be the fast mover (likely to be the west coast one). We might even see a bit of an organized line up of showers and storms along the west coast by noon time marching steadily eastward.

THURSDAY-MONDAY:  Next Transition will be  in full gear by early afternoon on Thursday for deep easterly flow to ensue by late evening. There could be morning and early afternoon showers and storms along the East Coast transitioning westward by mid-afternoon, with the strongest storms far interior and west side late in the day, although a few could be retained just about anywhere Central..esp. near Lake Okeechobee and into Osceola County through Lake County..western Orange county. SE Florida should end with the rains earliest.

After Thursday, things look pretty dry through the weekend- Monday for other than SW Florida.

No tropical entities are at hand, and none are expected. The tropical wave now over Cuba should wash into the Yucatan as the trough digs down the U.S. East Coast Tuesday. Things could become more active though heading into mid-August...that is climo...and hints are already in the cards for as said.

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