465 FXUS62 KKEY 161900 AFDKEY Area Forecast Discussion National Weather Service Key West FL 300 PM EDT Sun Oct 16 2022 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 245 PM EDT Sun Oct 16 2022 Clusters of showers and a few embedded thunderstorms were spreading northwest through portions of the middle and upper Keys. The eastward transit of high pressure off the southeast U.S. coast was allowing lower tropospheric winds to becoming more southeasterly, while remaining disconnected from the west to northwest flow 700-500 mb as mid level high pressure continued over the south central to west central Gulf of Mexico. While the Lower Keys had exited the cloudy and rainy skies early this morning, the highly-sheared convective cells further up the Keys would provide a quick heavy downpour with gusty winds with a slow trailing off of rainfall. GOES16 TPW imagery indicated the Keys remain entrenched in deep tropical moisture, and as earlier noted by regional soundings PW could be a tenth of an inch higher than the retrievals suggest. The slow pivit with dry air drifting slowly down the southeast Florida coast versus the slow northward drift up the west coast as the lower tropospheric high moves east seems to offer little change for tonight's weather in the Keys. Through midweek, heights will fall across the eastern U.S. with deep cyclonic flow as the mid level hight over the Gulf flattern and retreats southward. Differences continue in timing of a frontal passage in the Keys, with the GFS most quick in terms of winds, drying, and a first taste of cool air advection. Precipitation appears to linger in the anafrontal environment, with mesoscale regional guidance such as the NAM suggesting some instability may remain aloft vs the quicker GFS depiction. A slight chance of thunder was left in the Wednesday forecast, although confidence in such decreases later that morning and afternoon. In any case, drying occurs aloft mitigating thunder threat for late week, with a quick moderate to fresh northerly breeze ushering in sub-70F dewpoints and temperatures down in the lower 70s by Thursday morning. Howeven, even the GFS keeps moisture streaming aloft at 700 mb with an upper shortwave trough digging aloft over the Florida Peninsula. Confidence is not very high in weather there could be simply be a more cloudy, sprinkly post- frontal environment or a Thursday with scattered gusty showers or shallow depth. By the weekend, heights rise over the Gulf of Mexico with a tilted ridge extending northeast, producing northeast flow with perhaps some modified hybrid continental/Atlantic maritime mixed air. The challenge then will there be some leftover troughing aloft to perhaps act on the lurking deep moisture nearby with the stationary front to our southeast. && .MARINE... Issued at 245 PM EDT Sun Oct 16 2022 No watches, warnings, or advisories are in effect for Florida Keys coastal waters zones. East winds were generally 12 to 16 knots but gusty with surges produced by northwest-moving showers. Seas had settled below 1.5 feet at the buoy west southwest of Sand Key, which are waters not impacted by showers for much of the day. High pressure along the southeastern United States coast will shift eastward and weaken tonight through Monday. Moderate breezes tonight will diminish and become light by Monday evening. A weakening cold front wil approach the Florida Keys coastal waters Tuesday night, and move through the Keys with a northerly wind shift Wednesday. A period of fresh northerly breezes is likely in some areas late Wednesday through early Thursday. The front will become stationary over the eastern Straits of Florida or Cuba toward the end of the week. && .AVIATION... (18Z TAFS) Issued at 245 PM EDT Sun Oct 16 2022 VFR conditions are expected to prevail at both EYW and MTH for the rest of today and into tonight. Showers continue to linger around the island chain and may develop near either terminal. As a result, VCSH has been introduced for both terminals until this evening with TEMPO groups amended in as needed. Winds outside of convection will generally be out of the east at around 10 knots. && .CLIMATE... On this day in Keys' weather history in 1991, the daily record rainfall of 2.07" was recorded at Marathon International Airport. Rainfall records for Marathon date back to 1950. && .PRELIMINARY POINT TEMPS/POPS... Key West 78 86 78 86 / 50 50 30 30 Marathon 78 88 78 88 / 50 50 30 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...JR Aviation/Nowcasts....JAM 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