554 FXUS62 KKEY 130829 AFDKEY Area Forecast Discussion National Weather Service Key West FL 429 AM EDT Mon Sep 13 2021 .DISCUSSION... Currently - A surface through lower level ridge extends broadly across the southeastern United States and the adjacent Atlantic. This is producing gentle to moderate easterly breezes across the Keys and surrounding waters. Last evenings sounding is likely somewhat contaminated by an outflow boundary that swept through the area a few hours earlier, but it did indicate some low level inhibition which is consistent with shower activity struggling to hold together through the evening hours. The sounding did indicate precipitable water above 2 inches,, but a bit below the ~2.25 estimate of latest derived satellite imagery. Radar activity has more recently been trending upwards, with much of the activity concentrated over our eastern and southeastern waters. Forecast - Over the next couple of days the surface ridge acros the southeastern United States will gradually retreat eastwards into the Atlantic as Tropical Storm Nicholas migrates northward through the western Gulf of Mexico. The local pressure gradient will gradually relax and winds will trend downwards. For the near term, deep layered moisture will remain about half an inch above normal for this time of year. This along with a still healthy flow and at times no inhibition will continue the wetter than normal pattern. Will advertize likely pops for today, trending to high chance tonight. Outside raincooled areas, expect overnight lows to be near 80 and highs near 90. Heading into mid week an upper level low meandering over the greater Antilles and Bahamas will help to amplify a surface trough over or just northeast of the Bahamas. As this trough develops and tracks towards the Carolina Coast, expect the local pressures gradient to open up and winds will slacken significantly out of the southeast. Winds may go variable at times due to day time heating over the nearby large land masses. Rain chances should slip to near or slightly above normal due to the slackening flow and the reintroduction of more persistent but still weak lower level inhibition and slightly drier air above the boundary layer. In the latter part of the week the surface through lower level ridge will build westward across Florida as Nicholas and the Carolina low lift northeastward into the northeastern United States. With the ridge nearby, surface winds are expected to become gentle out of the east. Rain chances will remain generally near to slightly above normal due to weak inhibition and slightly above normal deep layered moisture. && .MARINE... A ridge across the southeastern United States and adjacent Atlantic will shift eastward further into the Atlantic as Tropical Storm Nicholas arcs north then northeastward into the northwestern Gulf states. Winds will relax further out of the southeast as a surface trough/low develops near or northeast of the Bahamas and Nicholes likely begins lifting northeastward through the central and eastern Gulf states. && .AVIATION... Shower activity is beginning to increase across the area yet again after a brief lull. Another wet day is expected at both terminals. There will likely be periods with decreased shower coverage throughout the TAF period, however, due to the uncertainty of timing and location, have included VCSH through tomorrow morning. Surface winds will be from the east at around 7 to 10 knots. && .CLIMATE... On this day in 1987, the daily record warm low of 86F was recorded in Marathon. This is also tied as the warmest low temperature recorded during the month of September. Temperature records in Marathon date back to 1950. && .PRELIMINARY POINT TEMPS/POPS... Key West 88 80 89 80 / 40 50 40 40 Marathon 88 80 90 79 / 50 50 40 40 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...11 Aviation/Nowcasts....NB Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest