Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
709 FXUS62 KKEY 181848 AFDKEY Area Forecast Discussion National Weather Service Key West FL 248 PM EDT Wed Sep 18 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 300 PM EDT Wed Sep 18 2024 Currently - Persistent mid and upper level troughing aligned over the southeastern United States, along with considerable lower level moisture is maintaining a wetter than normal setup across the Keys this afternoon. An associated weak surface trough/low off the Atlantic Coast is disrupting the usual residence of the Atlantic Ridge`s western flank leading to light and variable winds across the Keys. The weak flow is not helping much to prime the boundary layer or provide much in the way of convective triggers. That said, occasional rounds of shower and thunderstorms continue to fire across our area. Currently, activity is sparse with a few cells located west of Andros and far south of the Dry Tortugas. Cloud cover has thinned out sufficiently to let temperatures creep to near 90, while dew points remain in the mid to upper 70s. Forecast - The overall synoptic makeup is not expected to shift much over the next few days. The upper level trough axis will remain just to our west and should amplify further. Lower level moisture will remain ample. The trough off the Atlantic Coast is expected to slowly deepen and keep our winds light and often variable. As a result, above normal rain chances remain warranted. Rounds of convection is expected, interspersed with long recovery windows. Outside of convective influences, temperatures will range near normal. The pattern begins to shift heading into this weekend. The amplified upper level trough is expected to break with the core shifting off into the Atlantic and ridging moves down into the eastern United States. At the surface, this will result in ridging taking hold of the southeastern United States and the Atlantic trough deepening as it starts accelerating southeast to south towards the windward islands. This evolution will not kick out the broad swath of high lower level moisture, but winds are expected to begin firming up out of the east to southeast. There is probably a window where rain chances might come down, but it is too early for specifics. Will maintain slightly above normal pops with temperatures and dew points near normal. All guidance has been consistent with pressures falling in the northwestern Caribbean Sea early next week. The upper level flow is expected to become conducive for the formation of something. The development, or non development, of any system will be a significant component of Keys weather in this time range and beyond, and is something to pay attention to. && .MARINE... Issued at 300 PM EDT Wed Sep 18 2024 A weak surface trough/low off the Atlantic Coast will meander over the next few days and keep the pressure gradient and winds in the Keys light and aimless. The weak low is expected to deepen late this week as it begins accelerating southward. Its counterpart, ridging, will consolidate across the southeastern United States. Adding to the complexity is expected falling pressures in the northwestern Caribbean Sea early next week. Without projecting too much, it is expected that the combination of the above will result in gradually freshening east to southeasterly breezes through the long range of the marine forecast. Uncertainty is high, stay tuned. && .AVIATION... (18Z TAFS) Issued at 300 PM EDT Wed Sep 18 2024 VFR conditions will prevail at both EYW and MTH terminals. For the time being, shower activity is not expected to impact either terminal but will be monitored for any updates needed for later TAF issuances. Near surface winds will be southeasterly at 5 to 10 knots. && .CLIMATE... On this day in 1926, "the Great Miami Hurricane" made landfall in Miami at category 4 intensity, bringing Hurricane force winds to the Upper Keys. In Key West, the minimum pressure was 29.48", or 998 mb, and the maximum sustained wind was 52 mph. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 PM EDT Thursday for FLZ076. GM...None. $$ Public/Marine/Fire...11 Aviation/Nowcasts....AP Data Acquisition.....AP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest