"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, August 26, 2010

COULD Be Widespread Thunder For a Select Florida Area Today

Image: Storm focused mainly over N. Merritt Island yesterday made for a brief but pleasurable viewing experience along A1A in Cape Canaveral
RECAP: Very moisture laden SW-WSW mid-level flow pattern prevailed yesterday across Central Florida with the largest of storms over N. Merritt Island where a break in the cloud deck permitted the best surface heating. Lightning was hard to come by elsewhere other than further north toward Daytona. I was honestly surprised to see that Vero Beach reached 95 degrees yesterday! Just thought we could throw that in for good measure. Heck, the Miami area had a record high on Tuesday of 95 as well. So the summer of record highs (as well as record warm minimum temperatures) combined with prevalent warm mid-upper level temperatures continues.
SYNOPSIS: It's a mid-level features day for sure! Surface ridge axis extends from S of Bermuda across S. Florida to southern portions of Okeechobee County, whereas at the mid-levels it remains over the Florida Straits.  Mid level and surface low is pulling off the extreme NE U.S. Coast with an accompanying surface cold front reflection trailing SSW  to North Central Georgia where it starts to meet up with, yes...what I've been very loosely describing as remnant TD5 from over a week now! I've seen no discussions concerning this particular feature but have been eyeing it ever since the TD came ashore. It never lost some semblance of circulation at the 850mb level since that time, therefore I fondly refer to it as such.  A very weak surface and mid-level low, as it is, remains over extreme SW Georgia.
On the other hand, the surface low over the extreme W. Gulf is drifting south to almost the northern portions of the Bay of Campeche. This is interesting because there is a weak surface and mid-level reflection of an inverted trough extended NNW-WNW from this low to the low in Georgia. North and west of this trough a very strong and broad area of high pressure is encompassing much of the Eastern 1/4 of the country including the western Florida's only the peninsula that remains in warm, moist conditions until one heads west into S. Texas over to Arizona. It was COLD this morning in Minnesota, Michigan, Iowa, and Wisconsin with wide spread lows in the 40s and even a few upper 30s in North Wisconsin and Michigan. UGH! These cold temperatures are behind a dry cold front that is approaching the NE and Mid-Atlantic coastal region this morning.
...LOCALLY: Again, surface high pressure ridge extending from the Atlantic toward or just north of Lake O. Latest LDIS plots and surface obs indicate that there could be a weak boundary emanating from the low in the far SW Gulf across Tampa to the Space Center (aside from the more pronounced trough going into SW Georgia). Latest sounding data just came in confirming a continued SW-WSW flow just above the surface but weaker than the past few days. Temperatures aloft have changed nil from yesterday with 500mb near -5C and 700mb near 7C, with a PWAT just over 2". There is a bit of an inversion (and drying) near the standard  950mb level (500-1500 ft) which is right where cumulus clouds would form. It will take a while for this inversion to work out. Little change in the overall lay-out will occur today, other than that the mid-level ridge over the Florida Straits will move a bit further north toward the tip of S. Florida, and the very weak surface 'boundary' right across the center of the state will likely disappear with daytime heating, as will the aforementioned inversion. So things will start out very slowly with nothing to speak of across all of Central Florida.
TODAY: Opting to paint a 'worst case' scenario as far as potentially wet conditions are concerned despite how things currently look (as noted above). Might do an update when this scenario does not unfold though. As mentioned yesterday and based on latest model data, it does indeed appear that a sliver of strongest mid-level WSWterlies exists right over the immediate Central East Coast over Brevard County. Further south they are much weaker to almost nonexistent. Therefore, with some daytime heating believe the sea breeze will most assuredly develop first from near West Palm south (under the very weak mid-level flow) with a slight delay further north toward Brevard and points north. The sea breeze should make it as far west as Lake O further south then make less inland progress the further north one gets. Near South Brevard it will just barely make it to the Osceola County border and will likely impinge just barely west, if even, of US1 by the time one gets north of Melbourne...the US1-I95 corridor seems to be the breaking point the rest of the way up the coast to Jacksonville.
As was the case yesterday, a lot of what will occur in the early afternoon is contingent upon how much the mid-level cloud deck can break up. It will not break entirely...but there could be just enough of one to occur for another storm or heavy shower over N. Merritt Island to develop once the sea circulation develops sometime after 1pm. One developed there yesterday even without the sea breeze in play (might also point out this is a very localized 'playground affect' for shower and sometimes funnel clouds to form).  After this point expect further spotty showers and a larger Cumulus cloud field to form over all of the peninsula as we enter the peak heating hours (early-mid afternoon). 
Clouds should start to congeal into showers and eventually thunderstorms almost anywhere over the East half of Central and South Central Florida...but the further south one gets, especially near Lake O the further west the storms will form. Outflow from a storm over N. Merritt Island (if this does occur) will abet in aiding a localized enhancement of storm development further to its west and south along and west of the sea breeze front toward Seminole, Orange and Osceola Counties as well as northward into Volusia. This activity will move generally ENE-E in the prevailing mid-level flow and perhaps be further enhanced as it meets the pre-established sea breeze front, particularly from St. Lucie County north to Jacksonville. All this will occur later in the afternoon (after 3:30-4PM)...first affecting the inland portions.  Regeneration of showers and isolated thunder could continue, particularly over Central and North Brevard for quite some time due to remnant outflow interactions and/or remnant inland storm activity drifting toward the coast. As long as we're painting this 'worst case for wet' scenario, might as well go full bore in stating that the last of the rain...or probably more likely...a denser mid-level cloud deck..would be last to clear the coast in an area roughly outlined from near Oak Hill to Satellite Beach but well east of downtown Orlando-Sanford area south toward Deer late as 11pm tonight. 
As you can see, a lot could happen today over the most eastern portions of all of Central Florida..particularly from Volusia County south through St. Lucie County. Further south of there (which is Martin County)..things get very difficult to ascertain, especially if one assumes a good Lake O breeze develops. But do believe that any activity from Martin into PB County will be a "one time shot sometime late this afternoon deal", if at all.
FRIDAY: Synoptically speak...not a whole lot to go on. Mid-level flow will weaken even further and remaining cloud cover (regardless of what does or doesn't occur today) will be problematic. Similar sea breeze set up though but perhaps making it further westward than it will today. Chances are that storm probabilities will be officially be above average for this one last day.
SATURDAY-MONDAY: Point blank, BIG problem, but no big deal when push comes to shove. The cold front never makes it here, but rather the brunt of its force gets carried offshore north of the state as the big high pressure area broadens its expanse across all of the east 1/3 of the U.S initially. It looks now as though the high pressure will make its final build from the NNE and down the Florida east coast sometime late Saturday toward Sunday...sufficient moisture will still abound for at least clouds to exist in the meantime...and a final surge of NE-ENE winds at the mid levels will make head away around the ridge and onto the the Florida east coast as a 'backdoor' cold front. Convergence along this surge could provide enough lift for coastal showers to move in, first by Jacksonville Beach then southward with time to as far south as West Palm. This will occur sometime over the weekend, but timing at this point as to just when this will occur remains sketchy at best.
BEYOND MONDAY: We're in 'it' for the long run. "IT" being deep ENE-E flow with cooler coastal temps (below 90F) and no thunder pretty much everywhere expect for maybe a brief period along the immediate SW Florida Coast near and south of Ft. Myers.  Tuesday through next Friday will be defined by this uneventful, first signs of early fall flow pattern.
BEYOND NEXT FRIDAY: High pressure remains in control under thunderstorm shut-down mode, but transitioning to an early fall- onshore tropical 'like'' mode with coastal showers becoming an increasing issue. By later Thursday or Friday we might need to start watching for inverted troughs to impinge on the coast from the Cape and points south to the Keys under the base of the prevalent high pressure area extending across the mid-Atlantic states. Further north additional cold frontal blows will cross the Great Lakes region and the NE states and be of no impact locally.
TROPICS: By now most folks (or at least any one who reads this) knows about Hurricane Danielle and it's tease with Bermuda. Believe the high pressure area and preceding front will be enough to divert this storm from the island in the nick of time, but I bet the folks living there aren't taking it so lightly and will be on the edge of their seats until the storm makes a definitive turn.  Erstwhile, TS Earl could become a hurricane as well. It's course is less certain...despite the fact the models divert this system as well...don't be too quick to judge. But I'd place my bets on that becoming a reality. It's what comes next which would eventually be Friona that I'd be watching. As we work toward next weekend the strong high pressure over the mid-Atlantic states could work further east and prevent future tropical storm development from heading toward Santa's Palace...placing a larger threat on Puerto Rico and the Dominican Republic. This would be as we approach mid-September and the peak of Hurricane Season.

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