Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
681 FXUS62 KKEY 120813 AFDKEY Area Forecast Discussion National Weather Service Key West FL 413 AM EDT Sat Sep 12 2026 ...New DISCUSSION, MARINE, AVIATION... .KEY MESSAGES... - Moisture will linger across the region through the weekend, supporting slightly above normal rain and thunderstorm chances. - The primary threat for any stronger thunderstorms will be lightning strikes. When thunder roars, go indoors. If on a boat, stay low, or go below. - Heat index values will range from 100-108 degrees daily with little relief from the muggy conditions overnight. Know the signs of heat stress, take frequent breaks, and stay hydrated. && .DISCUSSION... Issued at 400 AM EDT Sat Sep 12 2026 A surface through mid level Atlantic ridge stretches westward across the Florida Peninsula into the Gulf of America. This has resulted in gentle to moderate east to southeasterly breezes across the Keys and surrounding waters this evening. Last evenings sounding indicated the precipitable water was around 2 inches and the 75th percentile for the day. CAPE was ample, however a stable layer was evident around 950 mb with modestly drier air. This may have contributed to the overall limited convective activity across the area this past afternoon and evening. Surface conditions are certainly sultry with temperatures in the mid 80s and dew points in the upper 70s. Over the next few days, the surface through lower level ridge will retreat into the Atlantic as a mid latitude trough takes shape and pushes off the Atlantic Coast. The remaining ridge to our north will weaken and mainland day time heating will effectively batter the surface ridge. As a result, east to southeasterly breezes should trend downwards with bouts of variability. A moisture rich swath across the Central Bahamas and eastern Cuba is expected to spread westward across our area through the weekend and should help to keep rain chances above normal through at least today. The weakening steering flow with no support aloft may counter this some. For now will maintain the already advertised 50% PoPs for today, which is below global models and above the NBM. No trend in temperatures or moisture is expected. Highs will remain near 90, lows in the lower 80s and dew points in the upper 70s. Through the first half of the weak, sharp deep layered ridging will build over the eastern United States as the mid latitude trough moves out to sea. This will setup robust surface ridging stretching along the Atlantic through Gulf coast states while an unusually amplified surface through lower level trough off the Atlantic Coast. A band of stronger northeasterly breezes will develop off the Southeast Atlantic Coast, Florida, and the Gulf. While there is uncertainty with how this unfolds, there is the added uncertainty as to how far south this band will reach. For now guidance shows breezes firming up slightly out of the northeast to the east for the Keys. Surface dew points may actually slip into the mid 70s for a change. Rain chances may be near to slightly However, for now, rain chances are expected to be near normal early in the week due to some drying and stabilization coming with the northern fringes of a Saharan layer. However, chances should return to slightly above normal heading into mid week as as band of lower level moisture pushes southwestward into our area. && .MARINE... Issued at 400 AM EDT Sat Sep 12 2026 An Atlantic ridge reaching westward across the Florida Peninsula will be battered daily by day time heating. As a result, while winds will generally be light to gentle out of the east to southeast over the next several days, periods of light and variable will likely. Heading into the middle of next week, a robust high pressure system building down the eastern United States will reinforce the pressure gradient, freshening northeast to easterly breezes. There is considerable uncertainty regarding how far south the belt of stronger winds can extend, and the Keys may just just remain out of most of it. && .AVIATION... (00Z TAFS) Issued at 400 AM EDT Sat Sep 12 2026 VFR conditions will prevail at the island terminals today. Shower and thunderstorm potential will remain near to slightly above normal. Surface winds will be light to gentle out of the east. && .PRELIMINARY POINT TEMPS/POPS... Key West 92 82 92 81 / 50 30 40 30 Marathon 90 82 90 82 / 50 30 40 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...AJP Aviation/Nowcasts....AJP Data Acquisition.....RG Visit us on the web at weather.gov/key Follow us on Facebook and X at: www.facebook.com/nwskeywest www.x.com/nwskeywest