Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
202 FXUS62 KKEY 020211 AFDKEY Area Forecast Discussion National Weather Service Key West FL 911 PM EST Sun Nov 1 2026 ...New SHORT TERM, MARINE, AVIATION... .KEY MESSAGES... - Coastal flooding will continue through the next several days, especially in the Upper Keys. - A wet, stormy period will continue through Monday. Locally heavy rainfall, especially when coincident with high tides, will exacerbate coastal flooding impacts. - Much drier conditions are expected for Tuesday through the remainder of the work week. && .SHORT TERM... Issued at 822 PM EST Sun Nov 1 2026 Water vapor imagery highlights a high amplitude trough-ridge- trough triplet across the CONUS this evening. The trough in the Gulf had a 70 knot jet streak dive into its base over the past 12-hours. All the derived upper level forcing fields (Die Vort, Pot Vort, and Die Div) suggest potent forcing over the eastern Gulf and Florida. Low level streamline analyses place the Keys in weak speed convergence with very little anticyclonic or cyclonic curvature. Current radar imagery highlights much less coverage across the Keys compared to this morning, and also across Florida compared to this afternoon. However, the occasional boundary interaction continues to be successful. The 00Z KKEY RAOB sampled moderate ML CAPE and weak inhibition, coupled with a relatively disheveled vertical wind profile. The forecast for the next 24-hour will feature likely rain and thunderstorm chances through Monday afternoon. Low level streamlines will become more confluent and cyclonic by sunrise on Monday, and with the decreased heights aloft and upper level support, the advertised rain chances (80% tonight, 70% Monday) appear appropriate. Overnight lows will fall into the mid 70s, and breezes will be slightly enhanced across our eastern waters where a SCEC remains in effect. No changes are needed with this forecast cycle. && .DISCUSSION... Issued at 1255 PM EST Sun Nov 1 2026 The sun rose on a much more active day than expected for the Florida Keys. Widespread showers and thunderstorms were able to develop across the western half of the Florida Keys. Peak rainfall totals were observed between eastern Key West and Big Coppitt Key. Accumulation totals between 2 and 5 inches of accumulation were estimated based on MRMS and unofficial rain gauges across the Lower Keys. The atmosphere ended up being too saturated to observe hazardous wind gusts. Advected Layer PWAT satellite estimates showed deep plumes of moisture from the surface through 500 mb across the Keys. Point being, a lot of moisture existed in the environment. The atmosphere finally stabilized over the Lower Keys by noon. Showers and thunderstorms will still be able to wax and wane from the Towers to the Middle and Upper Keys, but deep convective thunderstorms are less likely this afternoon. What was going on this morning, and why did we observe such heavy rainfall across the Lower Keys? Deep layer ridging set up over the eastern United States. The surface high associated with this ridge set up over New England. In the meantime, a shortwave trough set up over the northeastern Gulf. The trough was able to weaken the pressure gradient across southern Florida just enough to slacken the breezes across the Florida Keys. Breezes were also able to veer slightly to the southeast, and the combination of wind speed convergence and directional confluence was sufficient to sustain vigorous thunderstorms. Meanwhile, the upper altitude trough provided a source of upper altitude divergence to further fuel convection. What happens tonight and tomorrow? The shortwave trough is stuck in a region of broad upper level ridging and will not be able to move east quickly. Upper altitude dynamics are likely to remain over the Keys through tomorrow at the latest. The problem is that the US High will move further into the Atlantic. The pressure gradient is expected to continue to weaken across the Keys, suggesting the wind speed convergence will become less focused. Breezes will be stronger on the northern end of the CWA, which suggests shower coverage will be higher closer to south Florida. More rounds of showers and thunderstorms are possible for the island chain and the nearshore waters. Weather conditions are expected to calm down quite a bit after Monday for the Florida Keys. Eastward movement of the Atlantic High and a pronounced trough over the central United States will act to direct most of the energy from the Gulf into the eastern US. The upper level trough will linger, but without a broad source of lift, breezes are expected to slacken to light to gentle by mid-week. Late in the week, model ensembles suggest a frontal boundary associated with the central United States trough will pass across the Florida Keys. The problem is that right now, models do not show consensus on where and when the front will move across the island chain. One group of model ensembles suggests dew points could drop into the mid 60s, while another does not lower dew points below near 70. We will keep monitoring this feature. While this forecaster would appreciate dew points lowering into the 60s, that is not a guarantee, and check back later in the week for more updates! && .MARINE... Issued at 822 PM EST Sun Nov 1 2026 Small Craft Should Exercise Caution across eastern portions of Hawk Channel and the Florida Straits. Elevated northerly swell will persist through Tuesday for the waters southeast of the Upper Keys. Broad wind convergence across the marine zones will keep shower and thunderstorm chances high through Tuesday. Expect slackening breezes and drier air during the middle of the week for all marine zones. && .AVIATION... (00Z TAFS) Issued at 822 PM EST Sun Nov 1 2026 TSRA impacts at both terminals appear likely by the morning (09-15Z) and possibly extending into the afternoon and evening. The low level flow will become confluent and cyclonic overnight, combined with a moist and unstable vertical profile. Any convective impacts will include MVFR CIGS, IFR VIS, and localized wind gusts near 25 knots. && .PRELIMINARY POINT TEMPS/POPS... Key West 75 83 76 84 / 80 60 40 30 Marathon 76 84 77 85 / 80 70 50 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 AM EST Monday for FLZ076>078. GM...None. && $$ Public/Marine/Fire...CLR Aviation/Nowcasts....CLR Data Acquisition.....RF Visit us on the web at weather.gov/key Follow us on Facebook and X at: www.facebook.com/nwskeywest www.x.com/nwskeywest