Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
190 FXUS62 KKEY 131901 AFDKEY Area Forecast Discussion National Weather Service Key West FL 301 PM EDT Tue Aug 13 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 245 PM EDT Tue Aug 13 2024 Surface analysis depicts a relatively chaotic synoptic pattern for the eastern third of the United States, extending into the North Atlantic. The climatological high pressure and associated ridge axis in the North Atlantic weakly extends westward toward South Florida. This is being modestly disrupted by a weak stationary front draped over the Southeast. For the Keys, the net resultant wind vector owed to these pressure features is light to gentle east to southeast flow. KBYX radar has been detecting occasional isolated showers propagating through the Florida coastal waters. In addition, owed to the light steering flow, a broken cumulus cloud line has been waxing and waning across the Lower Keys, where a waterspout was earlier observed between Cudjoe and Sugarloaf Keys. Skies are generally partly cloudy across the island chain. The main weather story continues to be the at times oppressive heat. Heat indices have been flirting with 100-113F at many communities for the past several hours. For tonight, meteorological reasoning suggests a residual boundary should remain in the vicinity of the Lower Keys. Occasional showers should continue to progress from the Straits of Florida towards the island chain, which may interact with this quasistationary boundary near the island communities. Inherited low-end chance level PoPs for tonight, and given this setup, this still seems reasonable. CIMSS satellite-derived total precipitable water product suggests a wave of drier air is progged to reach the island chain around sunrise tomorrow morning. This, combined with light steering flow, should result in reduced rain chances for tomorrow. The exception to this will be the possibility of yet another island cloud line forming in the vicinity of some of the island communities. Beyond tomorrow, the main feature of interest will be a weak backdoor moisture boundary that should progress southwards towards the Keys by Friday before stalling. This will provide a bit of added lift. Combined with deep moisture ahead of the boundary sampled in forecast soundings, elevated rain and thunder chances appear likely for Friday through at least Sunday. The boundary should push through the Keys by Saturday night, resulting in a brief relief in the oppressive dew points for several periods. Until the backdoor boundary pushes through, the heat will continue to be the main weather hazard. Combined with light winds and ample solar insolation at times, heat indices will likely continue to exceed 110F at times through the end of the work week. Heat Advisories can be expected during the daytime hours for these periods, and Excessive Heat Warnings may also need to be considered. && .MARINE... Issued at 245 PM EDT Tue Aug 13 2024 There are no watches, warnings, or advisories in effect for the Florida Keys coastal waters. From synopsis, as an Atlantic ridge axis stretching west across South Florida will support light to gentle easterly breezes through Wednesday. Breezes will shift to the northwest by Thursday night, as a trough dips south along the Eastern Seaboard. As the ridge axis fractures over the Florida Peninsula, breezes will become more chaotic for Friday through Sunday. Strengthening Tropical Storm Ernesto near the Leeward Islands will slowly turn northward, likely impacting the island of Bermuda as a hurricane Friday night through Saturday. && .AVIATION... (15Z TAFS) Issued at 245 PM EDT Tue Aug 13 2024 VFR conditions will prevail at both EYW and MTH through the TAF period. With a cloudline formed over the Lower Keys, VCSH is included until this evening when the cloudline will break apart. Near surface winds will be easterly at near 5 knots. && .PRELIMINARY POINT TEMPS/POPS... Key West 84 92 84 92 / 30 20 30 30 Marathon 84 92 84 92 / 30 20 30 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory until 7 PM EDT this evening for FLZ076>078. GM...None. && $$ Public/Marine/Fire...BT Aviation/Nowcasts....AP 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