Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
436 FXUS62 KKEY 062040 AFDKEY Area Forecast Discussion National Weather Service Key West FL 440 PM EDT Thu Jun 6 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 430 PM EDT Thu Jun 6 2024 A particularly warm, dry, and muggy afternoon currently across the Florida Keys. Satellite imagery is detecting mostly sunny skies across the Florida Keys. Temperatures are hovering near 90F, with dew points in the upper 70s. KBYX radar is not currently detecting any meteorological echo returns throughout the Florida Keys as well as the adjacent nearshore and offshore coastal waters. However, outside of our forecast area, convection is beginning to flourish across the island of Cuba and over the South Florida Mainland. CIMSS satellite-derived vorticity analysis highlights a 500 mb shortwave trough southwest of the Florida Panhandle, as well as the base of a more equatorward-displaced 200 mb trough approaching the extreme southeastern Gulf of Mexico. Based on these features, it`s not surprising the 12z sounding at KEY sampled modestly falling geopotential heights at nearly all mid- and upper- tropospheric isobaric levels, along with virtually no capping inversion. The sounding also sampled a decent low-level veering profile, and a stubborn dry layer between 950-850 mb. Tonight`s forecast is unusually challenging. Satellite-derived precipitable water products suggest the aforementioned dry air sampled this morning has likely been replaced with more moisture advecting in from the south. If this is indeed the case (we will know after the 00z evening sounding at KEY), there is really nothing stopping convective development in the overnight period after midnight. Much better upper-level support for ascent along with more robust boundary collisions and limited inhibition should support this evolution after midnight. Virtually all available mesoscale model guidance supports this evolution at some point overnight or around sunrise. Although we advertise light southerly breezes overnight, any stronger thunderstorm will support locally gusty winds. Ensemble global guidance suggests the trough features will take a bit to exit the Florida Keys, and unsettled conditions are expected through at least Friday night, before the climatological mid-level ridge tries to briefly reestablish itself over the Keys for much of the weekend. The degree of height rises will determine rain chances, but we continue to trend on the drier side for these periods. It is worth mentioning that forecast confidence for this weekend forecast is on the low side. Forecast uncertainty only continues to grow with time for much of next week. Ensemble guidance suggests a trough will approach the Southeast next week, which will likely draw deep, tropical moisture northward from the Yucatan Peninsula for an extended period. However, there is a large degree in spread regarding the evolution of this moisture, driven by three primary factors: how far south will this trough penetrate the Gulf of Mexico, whether surface cyclogenesis occurs in the vicinity of the southern Gulf of Mexico, and where the west-east moisture gradient sets up in the vicinity of the Keys. Current statistical ensemble solutions suggest measurable rainfall amounts for Monday through Friday ranging from a few hundredths of an inch to several inches of rainfall. Residents and visitors are encouraged to stay updated on the latest forecast, which will almost certainly change over the next several cycles. && .MARINE... Issued at 430 PM EDT Thu Jun 6 2024 Despite mainly dry conditions through this evening, scattered showers and thunderstorms are expected to develop after midnight tonight. Any stronger thunderstorm will be capable of producing gusty winds, as well as rapidly building and confused seas. From synopsis, weak high pressure over the west-central North Atlantic will slide further eastward through the end of the week, as a frontal boundary stalls off the Eastern Seaboard and over north Florida. This will result in light to gentle southerly breezes across the Keys coastal waters tonight through Monday. Southeast to south breezes will likely freshen for early next week, becoming gentle to moderate. && .AVIATION... (18Z TAFS) Issued at 430 PM EDT Thu Jun 6 2024 VFR conditions will prevail at both EYW and MTH through the TAF period. Near surface winds will continue to be east to southeast at 5 to 10 knots. For the time being terminals will remain dry, but later this evening into tonight there is a possibility of some shower activity with VCSH present in the TAF. && .CLIMATE... In 1881, Key West measured a daily record high temperature of 96F. This is also the warmest temperature ever recorded in June at Key West. June temperature records for Key West date back to 1873. && .PRELIMINARY POINT TEMPS/POPS... Key West 80 90 81 90 / 50 50 40 30 Marathon 81 90 81 90 / 50 50 40 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...BT Aviation/Nowcasts....AP/DP Data Acquisition.....AP/DP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest