Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
588 FXUS62 KKEY 041823 AFDKEY Area Forecast Discussion National Weather Service Key West FL 223 PM EDT Thu Jul 4 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 137 PM EDT Thu Jul 4 2024 Hurricane Beryl made its closest approach to the Florida Keys this afternoon, and as it moves west across the Caribbean winds will slacken from moderate to gentle breezes across the Keys. Deep layer ridging will slide in following the departure of the nearby tropical system. Temperatures rose to near 90 today with heat indices just below Heat Advisory criteria, and there are no features to suggest any relief to the high temperatures. Isolated showers are developing in lines of low- level wind convergence, but thunderstorms will be sparse and ephemeral. Statistical and hi-res guidance dropped PoPs to 10% overnight given the lack of any synoptic-scale features that would support convection. Overall the pattern indicates a mostly clear night for Fourth of July fireworks, though debris clouds from Hurricane Beryl may obscure stargazing. Climatological shower coverage and light to gentle breezes will last through Saturday night. However, two features will act in concert to provide a surge in moisture and shower formation on Sunday. A Tropical Upper Tropospheric Trough (TUTT) located over Bermuda as of noon will shift west following the deep layer ridge, priming the upper atmosphere for a plume of mid to upper level moisture. At the same time, a tropical wave following behind Hurricane Beryl will makes its closest approach to the Florida Keys and add a synoptic-scale feature supporting convection in the low levels. However, this scenario relies on multiple features to move in certain ways to allow thunderstorms to form, and the environment becomes very uncertain by Saturday. The first source of uncertainty is Hurricane Beryl. Where exactly will it move, how much will it weaken, and how will that change the movement of the deep layer ridge? That in turn effects how far west and south the TUTT will shift, which in turn butterfly effects the northward movement of the tropical wave. If the TUTT does not move as far south as the ECMWF and GFS currently suggest, then the two features will not phase together and showers are less likely on Sunday. Thus maintaining the 40% for Sunday PoPs, and increased the overall PoPs to a mixture of 20 and 30% to account for the possible increased amount of moisture. && .MARINE... Issued at 137 PM EDT Thu Jul 4 2024 Hurricane Beryl continues its westward trek across the Caribbean Sea, and made its closest approach to the Florida Keys this afternoon. Moderate breezes will slacken tonight and tomorrow as the pressure gradient subsides. High pressure and gentle breezes will mark the first half of the weekend. Gentle to moderate breezes will resume for the first half of the work week as high pressure builds over the Caribbean. && .AVIATION... (18Z TAFS) Issued at 137 PM EDT Thu Jul 4 2024 VFR conditions will prevail at EYW and MTH through tomorrow. Isolated showers may move across both terminals through the TAF period, however, confidence in exact timing is low so have left out VCSH for now. Surface winds will east at 8 to 14 knots, with occasional gusts of 15 to 20 knots through this evening. && .CLIMATE... On this day in 1947, the daily record low temperature of 71F and the daily record rainfall of 6.07" were both recorded in Key West. Rainfall record date back to 1871 and temperature records date back to 1872. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...AJP Aviation/Nowcasts....NB Data Acquisition.....NB Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest