Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
962 FXUS62 KKEY 161859 AFDKEY Area Forecast Discussion National Weather Service Key West FL 259 PM EDT Mon Sep 16 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 132 PM EDT Mon Sep 16 2024 Another quiet, albeit muggy, morning passed for the Florida keys. Dew points remain in the upper 70s to near 80, the precipitable water values over 2 inches measured by the sounding and derived from GOES imagery will persist through the night. Near surface breezes remain light and broadly southwesterly to westerly. Cloud lines over the Middle and Upper Keys are possible tonight, and waterspouts will be a concern for boaters through sunset. Surprisingly for September, baroclinic features will begin to impact the Keys tomorrow. Potential Tropical Cyclone Eight, located off the Carolina coast, is moving inland today and will merge with a longwave trough located over the southeast United States. Jet dynamics will develop off the Florida coastline and direct moisture-rich air across the Keys. The forecast challenge relates to where the trough axis moves and how close the jet develops to the Keys. If the trough stays further east, the Keys will be on the dry side of the longwave trough. If the trough moves further west, then a weak right entrance region will be located close to the Keys and enhance showers and thunderstorms. Thus, increased the probability of precipitation to 60 percent on Tuesday and Wednesday. Model confidence and timing is rather consistent in predicting a wet Tuesday and Wednesday. Model agreement after Wednesday, however, is all over the place. The source of uncertainty ties to how much the aforementioned trough deepens and where specifically it moves. Spread in statistical model guidance shows a disparity of over an inch of rainfall next Monday, as one example. Despite the developing trough, breezes will remain light to gentle outside of showers. Overall, expect a good amount of rainfall, cloud cover, and potential thunderstorms over the Keys this week. Please stay up to date for any changes. && .MARINE... Issued at 132 PM EDT Mon Sep 16 2024 A Coastal Flood Advisory remains in effect for the Upper Keys, and a Coastal Flood Statement remains in effect for the Middle and Lower Keys. Ponding on the typically favored roadways will peak at the times of the morning higher high tide in the Lower and Middle Keys, with little tidal cycle relief in the Upper Keys. Other than these minor coastal flooding hazards, are no watches, warnings, or advisories in effect for the Florida Keys coastal waters. From synopsis, light and generally variable breezes will continue through Saturday over the Florida Keys coastal waters. Winds and seas will be elevated around thunderstorms, particularly on Tuesday and Wednesday, though background winds will remain light and variable. A developing low pressure system off the Carolina coast will generate a higher northerly swell off the Upper Keys for Tuesday and Wednesday. The low will deepen into an upper level trough and slowly slide south towards the Florida Peninsula through Saturday. Unpredictability in the movement of this trough means confidence in the extended forecast is very low. && .AVIATION... (18Z TAFS) Issued at 132 PM EDT Mon Sep 16 2024 Despite tranquil conditions currently across the terminals, scattered showers and isolated thunderstorms are expected to briefly proliferate along a developing cloud line just north of the island chain late this morning or early afternoon. A window of VCSH is included in the TAFs for now, with possible amendments to account for likely short-lived impacts to visbilities and ceilings to be added as needed. A second round of, perhaps more widespread showers and thunderstorms, are expected beginning after sunrise Tuesday morning, when another window of VCSH is included for now. && .CLIMATE... On this day in Keys weather history in 2023, the daily record high temperature of 97F was recorded at Marathon International Airport. This is also tied for the warmest temperature ever recorded in the month of September for the Marathon area. Temperatures records for Marathon date back to 1950. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 5 PM EDT Tuesday for FLZ076. GM...None. && $$ Public/Marine/Fire...AJP Aviation/Nowcasts....BT Data Acquisition.....BT Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest