Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
159 FXUS62 KKEY 210233 AFDKEY Area Forecast Discussion National Weather Service Key West FL 1033 PM EDT Mon Jul 20 2026 ...New DISCUSSION, MARINE, AVIATION... .KEY MESSAGES... - Recently formed Tropical Storm Bertha is located across the northeastern Gulf, and the National Hurricane Center continues to issue advisories. This system poses no threat to the Florida Keys. - Heat indices may approach 108 to 110 degrees each afternoon for some Florida Keys island communities. - Saharan Air Layer plumes will transit the area through at least mid week, limiting rain and thunder chances. && .DISCUSSION... Issued at 1025 PM EDT Mon Jul 20 2026 Recently formed Tropical Storm Bertha is still churning over the northeastern Gulf waters, and practically crawling northwestward at 3 mph. A turn to the west-northwest or west is still expected sometime after Tuesday morning. Anyone with interests along the northern Gulf Coast is encouraged to check with the National Hurricane Center and local Weather Forecast Offices for updates. Closer to home, things have been mostly benign for this evening shift. Even with some low level moisture and a little bit of surface wind convergence, our KBYX radar was only detecting some showers and thunderstorms across the SE Gulf, outside of our marine zones. Even now, our radar is still detecting some low level cloud streamers, and their motion suggests there is still some convergence out there. However, the 00Z KKEY sounding wasn`t terribly favorable for substantial activity. The calculated PWAT value came in at 1.48", which just so happens to be the tenth percentile value. Satellite-derived PWAT values across the area are between 1,3" to 1.5", and this is just a little bit drier compared to the 1.7" to 1.8" we had last night when some thunderstorms rolled through. The stray thunderstorms that have come off of Cuba are currently having trouble holding their own as they drift northward toward the island chain, so the inherited slight chance for showers and thunderstorms seems reasonable. Temperatures along the island chain are currently in the mid 80s with dew points in the mid to upper 70s, so our heat indices are still in the mid to upper 90s. Gentle to modestly moderate breezes out of the south-southeast to south are near 10 mph, but any shower or thunderstorm that develops nearby will be able to produce gustier breezes around 20 to 25 mph, or so. With this being said, no changes are proposed to the inherited forecast package. && .MARINE... Issued at 1025 PM EDT Mon Jul 20 2026 As of 8 PM EDT, recently formed Tropical Storm Bertha was centered over the northeastern Gulf of America. Bertha is expected to crawl northwestward during the overnight hours into Tuesday morning, followed by a turn toward the west. On the forecast track, TS Bertha will move near or along the northern Gulf coast during the next several days. Closer to home, an Atlantic ridge of high pressure will extend to the Florida Peninsula for the next several days. Moderate breezes, especially across the SE Gulf will slacken to gentle to moderate this afternoon. Thereafter, breezes will continue to peak overnight and lull during the day through Thursday. && .AVIATION... (00Z TAFS) Issued at 1025 PM EDT Mon Jul 20 2026 VFR conditions are expected to prevail through the TAF period, but one or two observations of MVFR CIGs are possible due to low level clouds around FL025. Any MVFR conditions reported during the first half of the TAF period should be short lived. Surface winds will remain southeasterly at 5 to 10 knots, increasing to near 10 knots by 20/12Z. Keeping TAFs dry due to low rain chances, around 10 to 20 percent, with the best chance of any activity west of EYW. && .PRELIMINARY POINT TEMPS/POPS... Key West 84 91 84 91 / 20 10 10 0 Marathon 83 90 83 90 / 10 10 10 10 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...DP Aviation/Nowcasts....DP Data Acquisition.....11 Visit us on the web at weather.gov/key Follow us on Facebook and X at: www.facebook.com/nwskeywest www.x.com/nwskeywest