Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
520 FXUS62 KKEY 220317 AFDKEY Area Forecast Discussion National Weather Service Key West FL 1017 PM EST Thu Nov 21 2024 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 1015 PM EST Thu Nov 21 2024 A deep cyclonic circulation over the Ohio Valley is giving an early taste of wintry weather across the Northeast and central Appalachians, with a classic deep trough axis tilting to the northwest with height across Florida and the Gulf of Mexico. All this to say finally a deep influx of continental air becoming entreched across the Keys. The evening sounding confirmed a thin layer of moisture trapped beneath a 6C inversion based near 2200 feet off the surface. North-northwest winds were calculated around 28 knots beneath this inversion with deep cool air advection aloft. Temperatures across the island chain were narrowly confined in the upper 60s to around 70F, and while the thin stratocumulus has pulled back westward and southward, no doubt the general mid-70s sea surface temperatures across Florida Bay and Gulfside are having a moderating effect. Still, it`s not a bad start to true late autumn weather with the radar clear of precipitation echoes and precipitable water values falling to below half of what they were calculated at Key West 24 hours ago. Overnight, little change is expected with mesoscale guidance still anticipating a noctural density surge off the Everglades beginning during the early morning hours, with forecasted temperatures in the lower to mid 50s just north of the Bay. While upper Keys winds are just starting to become occasionally breezy, windy conditions are still expected to set in before dawn with no public forecast modifications necessary. && .MARINE... Issued at 1015 PM EST Thu Nov 21 2024 Small Craft Advisories will remain in effect for all Florida Keys coastal waters overnight. Winds were observed from the northwest around 18 to 23 knots sustained along the reef as well as well- exposed Gulfside locations. From synopsis: Fresh to occasionally strong northwest to north breezes are expected overnight. Moderate to fresh northwest to northerly breezes will continue through Friday night, with considerable diurnal speed variations. High pressure will then advance eastward through the Gulf Coast states this weekend resulting in winds relaxing and veering to northeast to east. && .AVIATION... (00Z TAFS) Issued at 1015 PM EST Thu Nov 21 2024 VFR conditions are expected to prevail overnight into Friday. Stratocumulus cloud bases in the FL025-030 range may produce a brief moments of MVFR at EYW overnight, with the general trend favoring higher, above-MVFR bases toward morning. For Marathon, skies will likely stay clear. North-northwest winds are expected to continue 13 to 17 knots with frequent gusts near 25 knots overnight at EYW, with winds at MTH increasing after 06Z near those levels as well. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...Small Craft Advisory for GMZ031>035-042>044-052>055-072>075. && $$ Public/Marine/Fire...JR Aviation/Nowcasts....JR Data Acquisition.....MJV Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest