Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
445 FXUS62 KKEY 211902 AFDKEY Area Forecast Discussion National Weather Service Key West FL 302 PM EDT Tue May 21 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 256 PM EDT Tue May 21 2024 Synoptic composite analysis highlights an amplified shortwave trough with its axis east of the Florida Peninsula, with its counterpart upper-level ridge bridging over the Gulf of Mexico and now reaching our westernmost coastal waters. Meanwhile, at the surface, a weak area of low pressure east of the Bahamas continues to trek slowly eastward, with a weak area of high pressure over the Mid-Atlantic states building in its wake. The interaction of the low and high pressure features has resulted in a weak surface pressure gradient over the Florida Keys, with generally light and variable flow. The light flow has promoted a broken cumulus cloud line in the vicinity of the Lower Keys, occasionally dishing out a few showers. Outside of a couple stronger cells in the vicinity of Card Sound in the Upper Keys, mid- level dry air aloft is likely stinting shower activity from growing very deep. Outside of these showers, skies are partly cloudy across the island communities, with temperatures generally in the upper 80s. For tonight, drier air will continue to filter into the Florida Keys aloft. Shower and thunderstorm activity will likely be isolated in nature, associated with any potential weak nocturnal boundary collisions. Given the less organized nature of this convection with minimal upper-level support of ascent, did elect to nudge PoPs down to slight levels. The aforementioned ridge over the Gulf will continue to slide eastward, bridging over the Florida Peninsula by late in the week and into the weekend. Forecast soundings suggest formidable dry air aloft for these periods, and thus have retained very low PoPs and removed mention of thunder for Thursday through Monday. There are early indications in ensemble global numerical weather prediction guidance of yet another shortwave trough propagating across the Southeast and Mid- Alantic for the early to middle of next week. Should this pan out with a breakdown in ridging, this may provide the best measurable rain chances for the foreseeable future locally. In terms of temperatures, seasonably warm and muggy conditions will persist, with highs near 90F, lows in the lower 70s, and dew points generally in the lower to mid 70s. && .MARINE... Issued at 256 PM EDT Tue May 21 2024 There are no watches, warnings, or advisories in effect for the Florida Keys coastal waters. From synopsis, a weak area of low pressure in the vicinity of the Bahamas will continue to decay as it slides northeastward in the North Atlantic. As an expansive ridge of high pressure builds in its wake, light and variable breezes will gradually clock around to the east to southeast through Saturday, then to the southeast to south on Sunday. && .AVIATION... (18Z TAFS) Issued at 256 PM EDT Tue May 21 2024 VFR conditions are expected at the island terminals. With that said, the environment is capable of supporting convective development. This along with day time heating may result in a round or two of sub VFR conditions. Surface winds will be light and variable. && .PRELIMINARY POINT TEMPS/POPS... Key West 87 80 89 80 / 20 20 20 20 Marathon 87 80 88 81 / 20 20 20 20 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...BT Aviation/Nowcasts....11 Data Acquisition.....DR Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest