Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
161 FXUS62 KKEY 311407 AFDKEY Area Forecast Discussion National Weather Service Key West FL 1007 AM EDT Sun Aug 31 2025 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 1015 AM EDT Sun Aug 31 2025 Last night`s weather across the Keys continues to be unsettled. Another wave of numerous showers dissipated by sunrise, and GOES- East day cloud phase scans show dissipating cirrus clouds and stray cumulus across the CWA. KAMX radar returns highlighted a couple bursts of showers and a stray thunderstorm over the nearshore waters, but otherwise conditions are rather quiet. Winds along the reef this morning are westerlies near 10 knots, and temperatures along the island chain are already in the mid 80s. The morning KKEY sounding sampled nearly 2.25 inches of PWAT, safely above the 90th percentile, with only a shallow inversion holding back convection. The most significant change from yesterday`s sounding would be a more zonal wind field. Given the pattern remains very similar to last night, making no changes to the inherited forecast. Please note this does not mean the forecast is simple. The current pattern is highly chaotic and CAMS models show no consistency in timing convective initiation across the Keys. We are expecting a cloud line to form in the afternoon, and outflow boundaries generated by thunderstorms over South Florida or Cuba will need to be watched. Keep an eye out for thunderstorms, plus winds and seas will be much more chaotic near showers. && .MARINE... Issued at 1015 AM EDT Sun Aug 31 2025 No watches, warnings, or advisories are currently in effect for the coastal waters of the Florida Keys. From synopsis, somewhat unusual gentle westerly breezes prevail across the Florida Keys as our area is situated between ridging in the Caribbean and troughing along the Eastern Seaboard. This pattern will remain relatively unchanged throughout the forecast as the trough lazes over the east coast of CONUS while a surface low develops along the Georgia coastline. This low is progged to meander off into the western North Atlantic and rest on the west edge of the Bermuda High promoting an extension of the already established pattern in the Keys. && .AVIATION... (12Z TAFS) Issued at 1015 AM EDT Sun Aug 31 2025 VFR conditions will prevail through early afternoon hours. Another active period of scattered showers and thunderstorms is expected late this afternoon and tonight, but the exact timing remains uncertain. Amendments will be issued as conditions change. Otherwise, winds will be southwest to west near 10 knots. && .PREVIOUS DISCUSSION... Issued at 450 AM EDT Sun Aug 31 2025 The short term forecast is quite similar to what we observed yesterday. The Keys are currently situated between ridging in the Caribbean and troughing along the Eastern Seaboard thus allowing for westerly winds throughout a good chunk of our thermodynamic profile. Last night`s KKEY 00z balloon sounding confirms this with westerlies observed from the surface to just before 300 mb. The sounding also notes a PW of 2.13 inches, just 0.05 inches shy of the 90th percentile for today, along with an MLCAPE value greater than 2300 J/kg. It is no wonder why a wave of showers and thunderstorms was able to proliferate as well as they did. CIMSS MIMIC TPW shows our area is entrenched in similar PWAT values. Due to how unchanged our thermodynamic profile and our wind field is from yesterday, have opted to keep chance showers and thunderstorms in the short term forecast. Not much change to the overall pattern and the resulting sensible weather in the Keys over the next several days. While the trough along the Eastern Seaboard will shift east into the western North Atlantic, it is expected to stall out while a surface low develops off of Georgia`s coastline. While high pressure will build back into eastern CONUS, the stalled out trough and its surface reflection will keep Keys breezes westerly until the end of the week when high pressure finally spreads over mainland Florida. As little change is currently expected, persistence continues to be the best forecast with above normal PoPs at 50% along with a chance of thunderstorms. High and low temperatures will stay near 90 and in the lower 80s (outside of precipitation) respectively as breezes generally remain out of the west. && .CLIMATE... In 1889, Key West experienced its coldest August ever with an average temperature of 81.0F in each occurrence. In 1953, Marathon experienced its coldest August ever, with an average temperature of 81.9F. Monthly temperature records for Key West date back to 1872, and date back to 1950 for Marathon. && .PRELIMINARY POINT TEMPS/POPS... Key West 92 81 91 81 / 50 40 50 50 Marathon 91 80 90 80 / 50 50 50 50 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...AJP Aviation/Nowcasts....AJP Data Acquisition.....AJP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest