Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
008 FXUS62 KKEY 191935 AFDKEY Area Forecast Discussion National Weather Service Key West FL 335 PM EDT Tue Aug 19 2025 ...New AVIATION... .AVIATION... (18Z TAFS) Issued at 335 PM EDT Tue Aug 19 2025 VFR conditions will prevail at both EYW and MTH for the rest of today and into tonight. Storms moving south from mainland South Florida could cross the island chain near MTH this evening, but uncertainty in the exact timing and location of these showers will keep mention out of the TAFs for now. Near surface winds will be out of the northwest at 5 to 10 knots, increasing to near 10 knots. && .PREVIOUS DISCUSSION... Issued at 1155 AM EDT Tue Aug 19 2025 Nocturnal convection has mostly fallen apart this morning leaving the Florida Keys and its coastal waters largely rain free. KBYX is still tracking one small shower in the distant Straits off of the Middle Keys, but GOES-19 visible imagery notes mostly clear skies with a few fair weather cumulus stretched across our CWA otherwise. Hurricane Erin is currently east of The Bahamas and while it will continue to move off to the northwest, its influence on our wind field is observed along the Reef with gentle and somewhat variable northerly winds. Meanwhile, temperatures along the island chain are already near 90 with unfortunate dewpoints up to the lower 80s. More of the same weather is expected in the short term forecast. CIMSS MIMIC Layer TPW notes the same dry slot it did yesterday over south Florida and our area. This dry air can also be observed in the mid levels of this mornings KKEY 12z sounding and is mostly the blame for suppressed convective development today. Once again, we will be looking for late afternoon seabreeze convection from mainland to follow northerly flow into our waters. Usually this set up can cause a lot of rain to sweep through, but CAMs are not too thrilled with the set up possibly due to the unseasonably dry air aloft. Thus chance PoPs are held for now. Tonight and into tomorrow, breezes will continue to freshen out of the northwest and turn to the west. Rain chances will remain near or above normal due to excess moisture from Erin for the next few days. && .FORECAST... Issued at 339 AM EDT Tue Aug 19 2025 As of 5 AM EDT, Erin was located roughly 630 miles to the ENE of Key West. The system looks pretty large on satellite, and we can see some of the higher cirrus clouds across our forecast area are from the "exhaust" of Erin. The current forecast has the system turning to the north today. As Erin passes well to our east, moisture will advect from the north and showers and thunderstorms could be more efficient at producing heavier showers. With the fairly slow movement the system has, moisture will be able to sort of "build up" in the vertical profile, and it is possible that the 30 percent chance of rainfall we have advertised, specifically for Wednesday, may be a little too low. Regardless, the next couple of days have the opportunity to be a little wetter and a little cloudier than we think right now, it just depends on Erin`s motion. Once Erin pushes far enough northward, possibly from Thursday afternoon and onward, ridging will be able to build back in. Guidance is suggesting substantially dry air above 850mb, so our moisture source for any activity will be very shallow. Even though showers will still be possible, since it is August in Florida, a shallow moisture source means they will likely be short lived and unable to build into thunderstorms. The bottom line is that weather conditions should feel more normal once Erin pushes away, but you may want to keep an umbrella close until then. && .MARINE... Issued at 251 PM EDT Tue Aug 19 2025 No watches, warnings, or advisories are currently in effect for the coastal waters of the Florida Keys. From synopsis, hurricane Erin will continue to turn due northward over the open Atlantic going into tonight. The increasingly expansive circulation of Erin will result in a transition from light to gentle northerly breezes across Florida Keys coastal waters overnight, to gentle to moderate northwest breezes Tuesday and moderate to fresh westerly breezes on Wednesday. A slight swell from the north will lead to elevated seas in eastern portions of the Florida Straits and Hawk Channel. As Hurricane Erin migrates farther away toward the north and northeast, a weak subtropical high pressure ridge will settle over Florida Keys coastal waters, resulting in a lighter wind pattern Thursday through Saturday. && .PRELIMINARY POINT TEMPS/POPS... Key West 83 93 82 92 / 30 30 30 30 Marathon 82 91 83 91 / 30 30 30 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...JAM Aviation/Nowcasts....JAM Data Acquisition.....JAM Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest