"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".

Wednesday, September 29, 2010

Tropical Storm Warning Issued For the Treasure Coast - More Threats Possible Elsewhere

(Image: 7-8" rain producing storm over Port St. John. Note the mirror glass water. Wind at this time was light from the east. This is looking Northwest)
TROPICAL UPDATE: As of 5AM the tropical storm watch for Indian River, St. Lucie, and Martin Counties has been upgraded to a warning. A warning means that sustained tropical storm force winds are likely within the warned area. Further north, although Brevard County is not in the warned area, storm force gusts are possible in the heaviest of storms that could occur, mainly east of I-95. North of Brevard the concern quickly wanes due to the forecast track of TD16. More on this newly developed scenario is briefly discussed below under "TODAY".
NOW/LAST NIGHT: The storm system that generated a rainfall total of over 7" in Cocoa with possibly higher amounts toward Port St. John and lower amounts such as 3.52" in Cape Canaveral with slightly lesser amounts into South Brevard moved offshore and thinned out, with the last gasp dissipating near Cocoa Beach late last night. From that point on, a discernible baroclinic zone was established stretching from Cape Canaveral toward Port Charlotte on the SW Coast. One normally would not find such conditions this far south, as this is usually a mid-Atlantic to New England type synoptic set up. But given the depth to which the mid-upper level trough has dug over the past two days into the Deep South, we almost went "Summer Turned Winter" over night (did you see that Marianna, Florida yesterday morning was down to 52F degrees while the east coast was nearly 80 at sunrise?).
This zone sank south over night to a Naples to Vero Beach line. As such, all precipitation over night has been along and south of this zone. Meanwhile, TD 16 is located about 360 miles south of Cape Canaveral or 300 miles SSW of Ft. Pierce and is moving NNE at 14mph. The system appears to be becoming better organized. The strong convection that has been pounding Jamaica well to the east of the storm center has increased more toward the west or closer to the center of circulation. The system will cross Cuba during the morning and early afternoon and approach south Florida shortly thereafter.
TODAY: There is much hype locally for East Central Florida as events unfold (I'm hearing it on TV as I type), but there is a fly in the ointment. As noted, there is a baroclinic zone oriented South of Brevard County which is situated SSW from just south of Sebastian toward Ft. Myers. All precipitation over night and early this morning has been occurring south of this zone. So that's where we stand as of 6AM. Believe there is likely a coastal trough established just offshore as well, which as the sun rises and some heating ensues (and not much will be required)  will begin to retrograde toward the coast as early as 9AM. This seems more assured by early afternoon as the depression crosses Cuba and approaches S. Florida and surface winds gain a solid SE-SSE trajectory along the coast from the Cape and points south. The result would be something similar to what occurred yesterday, but probably not nearly as dynamic as that event as far as rainfall totals are concerned. (please refer to "*Important Note" below for disclaimer).
Rain has moved into the entire warned area as of this writing, and has just begun to penetrate extreme SE Brevard County near sunrise. I'm inclined to believe that given a few hours of daylight and backing of the surface winds, these rains will either translate onshore further north and/or simply fill in along a zone from Titusville SSW to Port Charlotte (or between Orlando and Melbourne south to Lake Okeechobee). Any storm activity could acquire rotation from noon on), particularly along the immediate coast from Cape Canaveral south where convergence is maximized along the coastal trough/baroclinic zone. This means that we might have some more tornado warnings again today. There were only a few warnings yesterday, and that will probably be the case again today. However, even if no tornado warning is issued, these cells could translate downward momentum to the surface and produce stronger/tropical storm force wind gusts along or near the coast outside the Tropical Storm Warning area, primarily east of I-95. The threat for rotating cell formation will wane quickly during the time this system, which at this point will likely, but not necessarily be named Nicole, exits the Florida East Coast.  Outside of this minimal threat, the greater threat will be heavy rainfall totals where cells train repeatedly or stack up over the same area.
As TD16 crosses the Florida Straits during the early afternoon it may be named Nicole. This is not really too important for landlubber though, since a majority of these winds will be east of the center of circulation (off shore). Given the fast motion the system will acquire as it starts to be united with the deep latitudinal trough digging down the U.S. East Coast, the system could pass across the land area of SE Florida with little affect on storm strength. It may in fact, be at its strongest as it passes east of Brevard County early this evening on its approach to the Carolinas before it become extra-tropical. Just because the system will become extra-tropical is neither here nor there though, as the storm systems interaction with the frontal boundary further north from the eastern Carolinas to New England will generate a much greater wind/rain hazard than Florida will ever know.
In any case, there is the possibility that what we'll call Nicole (give or take 5 mph of winds to make the difference between depression or storm), could make a few wobbles on a more northerly track during its crossing of SE Florida which would mean the system would exit off the east coast somewhere between Ft. Pierce and Vero Beach. Hence, the watch was upgraded to a warning.
(*IMPORTANT NOTES: (1) It would be irresponsible not to mention that the weather over the majority of Brevard/Orange/Seminole Counties might not be nearly as unaccommodating as the official forecast would lead one to believe. Namely, if the coastal trough / baroclinic zone does not retreat from its current location or only does so to a small degree, these areas could remain not rain free entirely, but would have significantly less hostile weather conditions than what we are being led to believe. Given the current synoptic scale set up is very rare for this time of year over Florida (where near winter meets the tropics), tremendous uncertainty on my part is admitted on how to deal with this situation). I'm picturing a Christmas card with Santa wearing a Speedo relaxing in a hammock stretched between two swaying palm trees).
(2) To take the level of uncertainty to up another notch, it is possible that should nasty weather develop, north of the warned area, it might be restricted to solely the intracoastal or even just the region from Cape Canaveral north to the Pads A and B. Should this be the case, activity of intensity worth noting would be limited to occur between 2-8pm today.)
TONIGHT: Conditions will rapidly be on the improving side as the storm makes its closest pass off the Space Coast. It may also be beginning to develop it's greatest strengthening phase as it passes the Cape over the Gulf Stream before making a second landfall in Central South Carolina by early Thursday.
THURSDAY-FRIDAY-SATURDAY: After  a slight chance of showers early Thursday, the remaining period will be quite pleasant with drier atmospheric levels (lower PWATS) and early fall conditions.
SUNDAY: The system will be out of everyone ones hair, but what evil lurks in the minds of the breeding season. High pressure to the north will combine with the continued simmering area of low pressure in the Caribbean to produce very breezy conditions along the coast from Ft. Pierce to Jacksonville. As these winds shift from NNE-NE-ENE that could usher in a shallow layer of moisture to the coastal communities. This moisture, combined with passage across the warm Gulf stream with steady winds could manifest as low topped ocean showers anywhere along the coast with breezy conditions for a number of days. Some minor beach erosion could become a concern, mainly north of Daytona Beach.
Meanwhile, the Caribbean won't be on its own. It's looking more like the forces from the Tropical Pacific as well as the Tropical Atlantic could be meeting up for generation of not 1, not 2, but perhaps three more systems during the first three weeks of October. At this time, the Bahamas appear to be most likely to be first affected by anything that would form. However, as we head later in time some transitions over the eastern portion of the continental U.S. will abet to generate a synoptic scale weather pattern that would result a tropical threat to somewhere in the NW Gulf, most likely Florida.

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