Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
079 FXUS62 KKEY 071840 AFDKEY Area Forecast Discussion National Weather Service Key West FL 240 PM EDT Sun Jul 7 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 230 PM EDT Sun Jul 7 2024 Mid-level vorticity analysis places an expansive ridge extending from the Gulf Coast all the way to the eastern North Atlantic, along with a weak tropical wave approaching central Cuba. Further aloft, a distinct Tropical Upper Tropospheric Trough (TUTT) cell is stationed southeast of the Carolina coastline. Finally, at the surface, high pressure extends across the Atlantic, with Tropical Storm Beryl slowly approaching the Texas coastline. All earlier shower and thunderstorm activity across the Flroida Keys coastal waters north of the Keys has dissipated, as a ribbon of mid-level dry air and southerly influences of Cuba have won the convective battle thus far this afternoon. Skies are mostly sunny across the the island chain. Temperatures near 90F, along with dew points approaching 80F, have resulted in another day of uncomfortable conditions, even by South Florida standards. As the aforementioned wave continues to progress westward south of the Straits of Florida, a brief window of deep, tropical moisture detected by CIMSS satellite- derived total precipitable water product should push through the Keys. Meteorological reasoning suggests any convection that develops over the diurnally-favored Cuban island locations should shoot northward in the southerly steering flow. All available mesoscale numerical weather prediction guidance supports this evolution, although there are various solutions as to if any developing convection can survive the trek to the island communities. After this convection passes, a wave of much drier, Saharan Air Layer (SAL) air will push across the Keys, and any shower or thunderstorm chances will quickly diminish to near-nil after midnight. This dry air will likely last through at least Tuesday. Thereafter, the TUTT cell is expected to dive southwestward towards the Keys. There remains quite a bit of model-to-model and run-to-run inconsistency as far as the strength of this cell once it makes its closest approach to the Keys late Tuesday night or Wednesday. In addition, forecast soundings suggest continued mid- level dry air during this approach. Given these competing factors, near-to or slightly above normal rain chances seems prudent for now, which will be evaluated each forecast cycle. Thereafter, the mid-level ridge will result in an extended period of east to southeast winds. All rain and thunder chances will be dictated by any moisture undulations or weak waves in the easterlies. Plenty of time to resolve any of these features, so continue to nudge the extended forecast to near climatology for now. Temperatures will remain the primary story for the Florida Keys. Heat Advisories will need to be considered for several forecast periods over the next seven days, as high temperatures remain near 90F, dewpoints stay in the upper 70s, and little relief is expected in the overnight periods. && .MARINE... Issued at 230 PM EDT Sun Jul 7 2024 There are no watches, warnings, or advisories currently in effect for the Florida Keys coastal waters. From synopsis, gentle southeast to south breezes will continue across the Florida Keys coastal waters through Monday, between high pressure over the western Atlantic and Tropical Storm Beryl over the western Gulf of Mexico. High pressure will build westward across the Florida Peninsula and into the Gulf on Tuesday, bringing gentle to occasionally moderate easterly breezes to the Keys waters for Tuesday through Thursday. && .AVIATION... (15Z TAFS) Issued at 230 PM EDT Sun Jul 7 2024 VFR conditions will prevail at EYW and MTH through tomorrow afternoon. While isolated showers near the terminals are possible overnight, timing and location of any shower development is uncertain, so have not included VCSH. Surface winds will remain from the southeast to south at 7 to 11 knots. && .CLIMATE... On this day in 2011, both the daily record cold high temperature of 83F and the daily record rainfall of 1.37" were both recorded in Marathon. Temperature and rainfall records date back to 1950. && .PRELIMINARY POINT TEMPS/POPS... Key West 83 91 84 91 / 30 10 10 10 Marathon 83 91 84 91 / 30 10 10 10 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...BT Aviation/Nowcasts....NB Data Acquisition.....AJP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest