Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
623 FXUS62 KKEY 241813 AFDKEY Area Forecast Discussion National Weather Service Key West FL 213 PM EDT Thu Sep 24 2026 ...New DISCUSSION, MARINE, AVIATION... .KEY MESSAGES... - Deep tropical moisture will linger near the Keys this afternoon, but supporting chances for scattered showers and isolated thunderstorms. - Drier air associated with a weak early season cold front will arrive tomorrow and into the weekend, resulting in near to below-normal rain chances. - Increasing northeasterly swell in the wake of the cold front will allow seas to build to 4 to 5 feet by the end of the week, especially in the easternmost Straits of Florida. && .MARINE... Issued at 213 PM EDT Thu Sep 24 2026 From synopsis: Unsettled weather will persist through the end of the week as deep tropical moisture lingers across the region which will support isolated to scattered showers and thunderstorms, mainly in the Straits of Florida. Breezes outside of convection will generally remain light to gentle northerlies. A frontal boundary is expected to push southward across the Keys waters tomorrow, resulting in freshening breezes, becoming gentle to moderate in the wake of the front. Winds should gradually slacken a touch over the weekend but will remain out of the north. In addition, seas across the eastern Florida Straits will build at the end of the week and into the weekend due to an incoming 4 to 5 feet northerly swell following the frontal passage. && .AVIATION... (18Z TAFS) Issued at 213 PM EDT Thu Sep 24 2026 VFR conditions will prevail at EYW and MTH for the upcoming TAF period. While SHRA can still form near the terminals during the evening, drier conditions will make VCSH conditions unlikely and resulted in their absence from the TAFs. Near surface winds are on track to stay generally northerly, but will shift between NNW and NNE. && .PREV DISCUSSION... Issued at 449 AM EDT Thu Sep 24 2026 After somewhat of a lull in activity earlier in the evening, scattered showers and a few thunderstorms have redeveloped in the Straits of Florida. However, compared to this time 24 hours ago, this is considerably less activity across our waters. Certainly not for a lack of moisture (2.44" PWATs measured by the 00Z KKEY RAOB), but rather diminishing synoptic-scale lift across the area in connection with an eastward shift in the low to mid-level trough axis over the western Atlantic. Much of the activity is currently focused in the Bahamas and off the east coast of Florida. Current surface obs indicate there is still some residual, albeit weak, cyclonic flow across the area associated with a remnant surface trough which will support at least isolated to scattered showers and a few thunderstorms. As we progress through the day, deep north to northwesterly flow will develop, and finally a weak, early season cold front is expected to pass through the area tonight. Mid-level dry air will surge southward across the Florida Keys by the end of the week as a secondary mid to upper-level trough ejects across the Mid-Atlantic region while broad, deep-layer ridging centered over the Texas coast begins to shift southward. As a result, PoPs will return to near normal or below-normal this weekend. Chance PoPs will be focused in the Straits of Florida where the aforementioned frontal boundary is expected to stall on Friday while chances remain much lower for the Island Chain and waters to our north. Deterministic models still suggest some potential for lower 70s to upper 60s dewpoints along the Keys, particularly Saturday afternoon. Highs will be in the upper 80s over the next couple of days, perhaps a couple of degrees lower this weekend, but it`s still too early in the season to expect a truly noticeable temperature swing behind this front. As far as winds are concerned, expect light to gentle west to northwesterly breezes today, freshening to gentle to moderate by tomorrow in the wake of the front. Associated northerly swell will result in building seas of 4 to 5 feet Friday into the weekend in the eastern Straits of Florida off the Upper Keys. Heading into early next week, the pattern across the CONUS finally looks to become more progressive as the stubborn ridge over the Southern Plains continues to break down and shift further south towards Central America. The upper-level low over the Western Atlantic is expected to deepen and become quite impactful for those along the Northeastern coast. As a result, a return of southwest to southerly flow and associated moisture resurgence is expected across the Florida Keys and surrounding waters by Monday and Tuesday as a secondary mid-upper level trough axis develops over the Southeast extending into the Gulf. This would potentially support near to above normal rain chances once again. && .PRELIMINARY POINT TEMPS/POPS... Key West 79 89 77 88 / 40 30 20 10 Marathon 78 88 78 87 / 30 30 20 10 && .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 X at: www.facebook.com/nwskeywest www.x.com/nwskeywest