357 FXUS62 KKEY 140817 AFDKEY Area Forecast Discussion National Weather Service Key West FL 417 AM EDT Mon Oct 14 2019 .DISCUSSION... Mostly clear skies prevail across the Keys on this early Monday morning. Radar shows scattered showers over parts of Florida Bay and the Gulf waters, but the Keys island chain remains dry, and very little shower activity is present over the Straits of Florida. Temperatures are hovering between 80 and 83 degrees, and winds on land are from the east to southeast at 10 to 15 mph. Surface analysis depicts high pressure centered off the Southeastern United States, with the Keys lying within a moderate pressure gradient along the SW flank of this high. The weak low level trough that moved through the Keys during the weekend is now over the SE Gulf of Mexico. Moist ESE low level flow prevails over the Keys in its wake, with MIMIC-TPW satellite imagery showing estimated PW values around 1.8 inches extending eastward from the Keys to Andros Island. The 00Z Key West sounding found ample moisture below 600 mb with PW of 1.91 inches, but the very dry airmass now present above 600 mb reflects the building mid/upper level ridge over the area. Water vapor imagery shows this deep/strong ridge extending from the Gulf of Mexico across the Keys and South Florida through the Bahamas. This ridge will be the dominant weather feature for the Keys during much of this week. For today, we expect the scattered showers currently on radar to remain mainly over the Gulf waters early this morning, with coverage likely decreasing later this morning. With decelerating easterly low level flow and the building ridge aloft, along with a drier airmass filtering into the area from the east, there appears to be little impetus for shower development, and will maintain just 20 percent rain chances. Otherwise expect plenty of sunshine with highs once again reaching the upper 80s. Mainly dry weather will continue for tonight through Thursday, as the deep ridge aloft provides dry and stable mid levels, and PWs run near to below normal for mid October. Although light winds expected for Wednesday through Thursday could support mesoscale processes such as cloud lines, the steadily lowering sun angle and suppressing influence of the ridge should prevent anything more than isolated showers, with deep convection unlikely. For tonight through Thursday, the forecast carries mostly clear skies, only 10-20 percent rain chances, and no mention of thunder. Rain chances should increase again toward the end of the week and into the weekend, as the subtropical ridge builds to the northeast of the Keys, with moist SE flow developing over our area. Have maintained 30 percent PoPs along with isolated thunderstorms. Otherwise, expect continued warm and humid weather, with no indication of fronts approaching our area through the upcoming weekend. && .MARINE... No advisories or cautionary headlines are currently in effect, and none are expected through the upcoming week. ESE winds have been running around 15 knots during the night at the C-MAN stations along the reef, with slightly lower speeds observed in the Gulf waters. Winds should lull a bit today, then surge slightly back to around 15 knots across the Straits, Hawk Channel and the deep Gulf waters tonight. That should be the final wind surge of the week, as the high to our north weakens beginning on Tuesday causing easterly flow to die out. An extended period of light winds is expected for Wednesday through Friday, with gentle ESE breezes finally returning to the waters beginning Friday night. && .AVIATION... VFR conditions are expected to prevail at both island terminals through the next 24 hours. Isolated showers early this morning will give way to only few cumulus based near 2500 feet with easterly surface winds near 10 knots. && .COASTAL FLOODING... Positive water level anomalies have increased during the past 24 hours and are now running around 1.2 feet above predicted levels at the Key West and Vaca Key tide gauges. The Blackwater Sound gauge also continues to run above predicted levels. A Coastal Flood Advisory remains in effect for the Middle and Upper Keys, while a Coastal Flood Statement remains in effect for the Lower Keys. This coastal flooding episode has been ongoing for almost three weeks now, and there is nothing to indicate that it will end anytime soon. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory for FLZ076-077. GM...None. && $$ Public/Marine/Fire...Jacobson Aviation/Nowcasts....WLC Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest