Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
236 FXUS62 KKEY 181903 AFDKEY Area Forecast Discussion National Weather Service Key West FL 303 PM EDT Sat May 18 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 231 PM EDT Sat May 18 2024 Water vapor imagery highlights a positively tilted mean- layer ridge centered over the Western Caribbean and the Bahamas. The next in an endless series of mid to upper-level lows is near the mouth of the Mississippi. A slightly squashed surface high stretches west- northwest through the Bahamas into the eastern Gulf of Mexico. Temperatures are in the lower to mid 90s and dewpoints are touching 80. Heat indices range from 105 to 110 and are above normal for May. .FORECAST... The oppressive heat will continue into Sunday with afternoon highs in the lower to mid 90s and heat indices climbing above 100. A pattern change is expected Sunday night and Monday as the upper low near the Mississippi pivots east and southeast around the mean layer ridge. Low-level flow will become more confluent as the heights fall aloft. A weak surface trough will fuse with the thermal trough on Monday, so SFC fields will be sloppy. Nevertheless, the MOS POP guidance suggests badly needed rain is on the horizon Sunday night through Tuesday. Once again, there is a large disparity in the rain chances and we continue to advertise a wetter solution (30/40%). Forecast soundings suggest very fat CAPE profiles above -10 degC and healthy storm relative wind. If low-level moisture convergence is as advertised by the Euro, thunderstorms with hail are not out of the question. By Tuesday night or Wednesday, the Keys will be on the western flank of the upper- level low including strong subsidence and very dry mid level air. The criminally high dewpoints should return to the lower 70s mid week. However, it will be hard to discount mesoscale rain chances along island cloud lines, off the Mainland, and within the developing east to southeast steering. We trend the forecast for Wednesday and beyond to near normal with slight rain chances (20%) and high/low temperatures near 90/lower 80s. && .MARINE... Issued at 231 PM EDT Sat May 18 2024 There are no watches, warnings, or advisories currently in effect for the coastal waters of the Florida Keys. The western extent of a low- level ridge axis extends west- northwest through the Bahamas and across the Keys. Southeast breezes will tend to peak and lull overnight through Sunday as the heating and cooling of South Florida and Cuba modulate the local wind forecast. There may be a break in the rain-free conditions Sunday night through Tuesday, followed by variable breezes turning to the east Wednesday through Thursday. && .AVIATION... (18Z TAFS) Issued at 231 PM EDT Sat May 18 2024 VFR conditions are expected through the evening and overnight hours at EYW and MTH. Latest hi-res model guidance continues to show the risk for isolated showers and thunderstorms to develop mainly well north of the Island Chain overnight through Sunday morning. Right now, this activity looks to remain north and doesn`t pose a threat to the terminals, though, we will continue to monitor. Therefore, VCSH was also left out of the TAFs with the afternoon update. Surface winds will oscillate between south southeast and east southeast over the course of the afternoon through the overnight hours, remaining between 6 to 12 knots. However, towards daybreak Sunday winds will begin to shift to more of the south to southwest. && .CLIMATE... Interesting climate tidbit so far for the month of May. Key West has hit 90 degrees so far 7 times this month with one more time expected Sunday. However, without even counting today and Sunday, the last 7 days have already broken the record for the hottest 7 day average temperature during the month of May. The previous record was 85.0 degrees which was set back in May 2017. Currently, the average of the last 7 days is 86.3 degrees which is an astounding 1.3 degrees above the previous record, thereby shattering it! && .PRELIMINARY POINT TEMPS/POPS... Key West 82 93 79 88 / 10 10 30 30 Marathon 83 91 80 88 / 10 10 40 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory until 6 PM EDT this evening for FLZ076>078. GM...None. && $$ Public/Marine/Fire...CLR Aviation/Nowcasts....MJV Data Acquisition.....MJV Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest