Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
605 FXUS62 KKEY 211730 AFDKEY Area Forecast Discussion National Weather Service Key West FL 130 PM EDT Thu Aug 21 2025 ...New AVIATION... .AVIATION... (18Z TAFS) Issued at 130 PM EDT Thu Aug 21 2025 VFR conditions will prevail at both EYW and MTH through the TAF period. A cloud line is currently attempting to develop along the northside of the island chain in the Lower Keys. No showers have formed as of now, therefore, no mention of VCSH included for the time being. Near surface winds will continue to be light and primarily south to southwesterly. && .DISCUSSION... Issued at 1058 AM EDT Thu Aug 21 2025 Shower activity has continued to diminish in both coverage and intensity through the morning hours across the Florida Keys. At present, only isolated showers are evident on KBYX radar. Outside of these now limited showers, much of the forecast area is experiencing partly cloudy skies. Temperatures along the island chain are currently in the mid 80s, gradually climbing towards near 90. Marine observations indicate light to moderate breezes, generally 5 to 10 knots along the Reef, though sea conditions in the Upper Keys remain influenced by swells generated from Hurricane Erin, located well to the northeast. As the day progresses, the development of a reserve cloud line remains possible, supported by the prevailing light breezes along the island chain. This cloud line could create a few light showers on land and a potential for a waterspout or two in the nearshore waters. However, the 12z KKEY sounding observations resulted in an in- house waterspout index of only 9%, which is lower than values typically observed during more favorable cloud line set up days. Outside of any cloud line development, additional isolated showers are expected across the CWA, with some cells briefly intensifying into a quick fuse thunderstorms. && .FORECAST... Issued at 429 AM EDT Thu Aug 21 2025 Outside of Hurricane Erin, the forecast for the next several days to week or more looks to remain rather benign. Hurricane Erin remains the main story for the next day or so as it is currently making its closest pass to the Eastern Seaboard. The storm will continue to move north northeastward before turning more northeastward by tonight while accelerating as it moves farther out into the North Atlantic. This will result in another day or two of southwest to west breezes. The Keys remain well to the southwest of Erin and are located to the northwest of the weak ridge trying to build in behind Erin across the southwestern Atlantic. Moisture is expected to remain rather plentiful again for today with GOES East Total Precipitable Water (TPW) products showing PWAT values of 1.7 to 2.0 inches across the Keys. Therefore, 30% PoP was maintained. However, the only real trigger we have to get any shower or thunderstorm activity are leftover mesoscale boundaries from earlier convection and potentially some very minor speed convergence today. There is also the potential for reverse cloud lines for the next few days as the pattern remains quite stagnant and winds remain light. This is typically a good pattern for cloud lines and waterspouts. We will keep an eye on this closely over the coming days. Other than that, weak ridging will build into the Keys for Friday continuing through the weekend and even much of next week. Slightly drier air is expected to move in for the weekend and next week resulting in 20% PoPs through the extended. Otherwise, the summertime heat and humidity will be the name of the game going forward with daytime highs in the lower 90s and overnight lows in the lower to potentially mid 80s. Heat index values will be consistently between 105 to 108 degrees each day. && .MARINE... Issued at 1058 AM EDT Thu Aug 21 2025 A Coastal Flood Statement is in effect for all of the Florida Keys through at least this evening. Elsewhere, no watches, warnings, or advisories are in effect for the Keys. From synopsis, Hurricane Erin will continue to move to the north northeast today. The system will turn to the northeast by tonight moving away from the Eastern Seaboard and out into the North Atlantic while accelerating. A slight swell from the north will continue to lead to elevated seas in eastern portions of the Florida Straits for another day or two. A weak subtropical high pressure ridge will begin to build into the Keys tonight before settling over the Keys through the weekend. This will result in generally light, occasionally light to gentle breezes. && .COASTAL FLOOD... A Coastal Flood Statement remains in effect for all the Florida Keys. Tides are running almost a foot above predicted. As a result, minor saltwater flooding of low elevation streets and lots is likely. Some storm drains will overflow, and some seawalls and docks will be overtopped. Boaters can expect less clearance under fixed bridges. Motorists should remember that persistent puddles around the times of high tide are almost certain to contain a mix of saltwater. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...AP Aviation/Nowcasts....AP Data Acquisition.....AP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest