"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".

Saturday, September 25, 2010

All Eyes on the Tropics

SYNOPSIS: Western fringe of high pressure over the southeast states lingers one more day as developing mid-upper level trough encompasses the Mississippi River Valley to the Great Lakes. Meanwhile, broad area of low pressure over the Caribbean into the extreme SW Gulf of Mexico, highlighted by Tropical Storm Matthew near La Ceiba Honduras. The storm is 'forecast' to eventually weaken over the weekend and become absorbed in a monsoonal low pressure area expected to form over Central America. We'll see. (do you detect a hint of uncertainty here? See more).
TODAY: Latest short term model (RUC) matched with the XMR (KSC) sounding shows the ridge remains over South/Central Florida, with the axis at roughly 15,000 Ft located overhead where winds are calm. Radar is showing very light rain returns moving from SW to NE. Believe these may not be reaching the ground for the most part, since their motion is SW to NE and would be a manifest of denser cloud patches associated at or just above the ridge axis aloft. The RUC indicates during the course of the day that these winds could lower to approximately 8,000 ft entering the mean steering current for late afternoon thunderstorm range; however, winds below that level (to the surface) remain solidly steady from the east for the most part. Atmosphere not as moist this morning as late yesterday with a PWAT at 1.80". Skies are mostly cloudy with a few patches of partly cloudy skies across the peninsula. Cloud motion is weak from SW-NE, namely with the mid-upper level clouds. Once low level cumulus clouds start to form they will move steadily from east to west.
Clouds may keep afternoon high temperatures down a few degrees today and preclude ample heating for thunderstorm generation until late when a boost will be provided by sea breeze convergence on the west side with a few pockets of Lake/Sea Breeze interactions thrown in. Wouldn't expect coverage to be very high at all though (i.e., would be isolated) and well west of I-95. However, with the winds aloft gradually becoming SW with time by late at lower levels, some of this activity may propagate back toward the coast from the Cape and points north in the early-late evening in the form of light or perhaps moderate rain fall.
SUNDAY: The ridge begins to break down even more, and might complete the transition after sunset. As such, similar conditions as today with a chance of thunder reaching the coast primarily from near Melbourne and points north by late afternoon. It should be noted that South Florida will be under going a completely different set of circumstances, most notably that the more westerly steering component does not become established down there. Moisture will be plentiful though, so what they will incur is a somewhat modified version of what has been occurring in the past few days...but perhaps less of it.
MONDAY-WEDNESDAY: Somewhat of a summer like pattern to prevail as a cold front associated with the deepening trough (and eventual cut-off low) over the Deep South becomes the playing factor for North and Central Florida early next week. This would be a summer pattern favoring the east side of the state for late afternoon thunderstorms and rain showers from West Palm Beach north to Jax. Cloud cover during the early portions of these days will be a factor in timing of what/when/where activity will occur, thus these days will require closer scrutiny on a daily basis.  At this time, there are hints that a well organized area of thunderstorms, and nearly a squall line of sorts for North Florida, could push into the panhandle which would push east and south to as far south as Daytona Beach or even extreme N. Brevard by Monday night. After which it should wash out with remnants lifted off to the northeast. Thus, we could see an up tick on thunderstorm potential/strength and/or coverage late Monday.
BEYOND: As we head toward the later portions of the week into next weekend much of the weather over South and Central Florida will be contingent upon what occurs over the western Caribbean which is a tremendously huge unknown, thus it would behoove the forecaster to go into details concerning the whys and where rain is most likely to occur, or for that matter, not to occur. If indeed, the organized line of convection does manifest and maintains itself into Central Florida, any remnant surface boundary left further complicates matters. Thus, we'll leave it at there 'should' be a continued chances of showers or at least cloud periods, with thunder quite possible.
TROPICS: Not going to go too deep into the tropical Caribbean at this time, but will illustrate why. Tropical Storm Matthew to drift toward the S. Yucatan region over the weekend and meander over this region. Models continue to indicate that it will either retrograde back east into the waters, or at least one, if not two, more low pressure areas could form any where from south of the Dominican Republic to South/Central Cuba. Models from this yet to occur event provide eventual solutions of a named storm Nicole moving north and either up the far eastern Gulf off the Florida West coast to further east just off the Florida SE Coast, contingent upon both the origination point and the timing coincident with the passing of a upper level trough to the north. Further down the road, the GFS latest solution actually takes a Nicole around the entire periphery of the Gulf with it ending back where it starts in the Bay of Honduras while another system which would be Otto, develops and moves quickly toward the NE over the Bahamas. This would leave Florida in between both systems with little impacts. But that's just one model describing what is already apparently becoming a very complex, yet to develop, situation. Other models indicate one solid storm approaching the Tampa Area...and another takes just one system near the SE tip of the state. Point is, this scenario could be a never ending story for the next two weeks as alluded to in the previous post. And to add fuel to the fire, the timing off the overall broad-brush picture might be delayed to even further out in time, as often occurs at this time of year. For you see, we not only have to monitor not only what is already an ambiguous situation in the Caribbean (as just described), but also what sort of developments occur closer to home over the continental United States during this time frame. How they eventually interact, whatever 'they' may be, will determine the outcome...which could be anywhere from late next week to late the week after that (or even beyond).

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