current from NHC TAFB & NWS Melbourne
Posted by cypresstx
on 9/29/2017, 9:11 am
Synopsis for the SW N Atlantic including the Bahamas
440 AM EDT Fri Sep 29 2017
.SYNOPSIS...A cold front will move into the northern waters Sat where it will stall this weekend. Surface low pres may develop between the western Bahamas and Florida early this weekend, possibly becoming a tropical cyclone. The low will drift NE through Sat evening, shifting back to the SW-W through Sun. Strong NE winds will develop NW of the low pres and behind the front.
310 AM EDT Fri Sep 29 2017
Today/tonight...inverted surface trough will lift northward into southern and central Florida over the next 24 hours. Global and mesoscale models show disparate solutions regarding the strength and placement of a surface low along this trough, with the GFS pretty much on its own now showing a slightly stronger low moving northward just offshore the ECFL coast. Interestingly enough, the position of the RUC analyzed H25 divergence maximum is near Key Biscayne, and the short range progs show this max moving northward just offshore the Florida east coast over the next H24, which does seem to support something close to the outlier GFS solution, at least position-wise. Consequently, the forecast will show a somewhat coherent surface low moving northward along and then a little offshore from late this, afternoon through tonight, reaching a position offshore NE Florida by sunrise Saturday. This should result in highest coverage (60-90 percent) of showers over the coastal counties from the Cape south, tapering to low-mid range scattered to the north and inland. Storm coverage should be limited by extent of clouds. temps will range from the M80s over the SE CWA to the L90s from around I-4 north and west.
Locally heavy rainfall may become an issue in a few spots, however expect convective bands to be progressive, which would limit the potential for training of echoes. As the low center moves northward, winds will shift or back to an offshore component, which will allow precip to taper off from south-north this evening-tonight. Highest POPs (50-60) will remain along the coast, mainly during the first half of tonight, although showers will likely linger through much of the night. Mins tonight will drop into the L-M70s behind the low.
Saturday-Sunday...A very messy weather pattern in store for this weekend across the Florida peninsula. Low confidence continues as location and strength of various features remain cloudy. Early in the period models forecast an upper low over the WCNTRL Gulf to slowly move southwestward toward the Mexican Yucatan peninsula. As this occurs mid-level ridging will strengthen over the Deep South including the FL peninsula. A weak surface low off of the northeast FL coast will spin off of the southeast U.S./north FL coast before being drawn back across the north FL peninsula late in the day on Sun, then continuing a westward movement into the northeast Gulf Sun night as a trough. Potential for tropical development of this feature still remains low-moderate at this time.
PWAT values will be around 2 inches or higher during this period as deep layer moisture remains elevated with more cloudy periods than not. Regardless of any tropical development, likely showers and a chance for lightning storms will impact ECFL through the weekend with potential breezy conditions at times. Highest precip chances will be along the coast and offshore with slightly lower chances inland.
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