Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
970 FXUS62 KKEY 261550 AFDKEY Area Forecast Discussion National Weather Service Key West FL 1150 AM EDT Sun Jul 26 2026 ...New DISCUSSION, MARINE, AVIATION, PREV DISCUSSION... .KEY MESSAGES... - A generally active pattern will remain in place with above normal to well above normal rain chances through mid week, peaking tonight and Monday. - Heat indices may approach 105 to 110 degrees each afternoon for some Florida Keys island communities, especially in the Upper Keys. && .DISCUSSION... Issued at 1112 AM EDT Sun Jul 26 2026 Our KBYX radar has been busy detecting pockets of showers and thunderstorms as they have been waxing and waning over the past few hours across our forecast area. Around 10 AM, a line of thunderstorms from low level convergence over the Gulfside waters brushed across the Lower Keys, bringing bouts of lightning and rainfall with it. The ASOS at Key West International Airport reported 0.13" of new rainfall from these showers, and this lines up pretty well with the radar- derived estimate of 0.05" 0.15" across Key West and Stock Island. MRMS highlights a pocket of higher amounts, 0.30" to 0.50", offshore to the north of Key West, Big Pine Key, and to the south of Marathon. Some island communities may have seen in the Lower and Middle Keys may have seen rainfall amounts just under the half inch mark, but we do not have any reports or observations to confirm that. Typically, we associate gusty conditions with thunderstorms, but wind observations showed sustained winds near 10 mph with this line. This was likely due to a combination of slow forward speed (around 5 mph) and towers that were not particularly tall (cloud tops around 15,0000 to 25,0000 ft). Upstream, troughing looks like it is digging into the South FLorida area. There is a general northwest to southeast motion to the cloud field upstream from the island chain, but a more southwest to northeast flow just to the east of us. The base of this troughing is likely across our area, so we expect surface winds to take on a northwesterly direction here any minute. Radar trends offshore of SWFL show that pockets of showers and thunderstorms are still firing, so even though we are entering a lull here, we continue to expect an uptick in activity again later. Hi res guidance is struggling a little bit with regards to timing, but has done well showing the up-and-down pattern in terms of activity on radar. The 12Z KKEY sounding from this morning shows a primed environment with approximately 2000 J/kg of ML CAPE with only around -16 J/kg of CIN to overcome. The profile was sufficiently moist with a calculated PWAT of 2.02", much higher than the daily mean of 1.77", so the 40% chance of rain inherited from the morning package seems reasonable. It just looks like the 40% will be more applicable to the second of this afternoon, rather than right now. No changes are proposed with this morning update. && .DISCUSSION... Issued at 428 AM EDT Sun Jul 26 2026 The Keys are expected to remain on the southern flank of a broad longwave trough across the Eastern Seaboard with ridging on either side of this trough. This will keep increased moisture and instability across the region for the next several days resulting in above normal to well above normal rain chances. Rain chances peak tonight and Monday when the moisture and instability across the area maximizes. Decreasing rain chances are expected thereafter as slightly drier air moves in and the longwave trough shifts off to the east. Outside of the rain and thunder chances, typical summertime heat and humidity will continue with daytime highs near 90 degrees and overnight lows in the lower 80s. Dew points in the mid to upper 70s combined with temperatures near 90 degrees will keep heat index values between 105 to 108 degrees with isolated locations to 110 degrees. South to southwest light breezes this morning will give way to light to gentle breezes this afternoon while also shifting to the west to northwest. At the surface, a frontal boundary is expected to remain draped across Florida for much of the week. This will result in mostly gentle to moderate southwest breezes. && .MARINE... Issued at 1112 AM EDT Sun Jul 26 2026 Surface troughing will continue to dig across the area today, causing light and variable breezes to back to the northwest and becoming gentle to modestly moderate. Pop up showers and thunderstorms will crawl across the local waters. Seas will be higher and waters will be rougher in, and near, showers and thunderstorms. Breezes will return from the southwest and west as the trough moves east of the Florida Peninsula early this week. There is growing confidence of a return to an active weather pattern starting tonight. && .AVIATION... (15Z TAFS) Issued at 1112 AM EDT Sun Jul 26 2026 Unsettled weather across the area will keep SCT to BKN clouds near FL030, so observations may show flight categories going back and forth between VFR and MVFR throughout the TAF period at both island terminals. The best chances for activity at either airfield look like they will be from now until around 22Z, followed by a brief lull, and then another round of showers and thunderstorms beginning near 06Z. Any strong thunderstorm may produce an instance of gusty crosswinds and reduced visibility. && .PRELIMINARY POINT TEMPS/POPS... Key West 90 82 90 82 / 40 50 60 40 Marathon 90 82 90 81 / 40 60 60 40 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...DP Aviation/Nowcasts....DP Data Acquisition.....DP Visit us on the web at weather.gov/key Follow us on Facebook and X at: www.facebook.com/nwskeywest www.x.com/nwskeywest