358 FXUS62 KKEY 090319 AFDKEY Area Forecast Discussion National Weather Service Key West FL 1019 PM EST Fri Jan 8 2021 .DISCUSSION... Partly cloudy, breezy and cooler conditions prevail across the Florida Keys on this Friday evening, in the wake of a cold front that moved through the area early this morning. Radar and surface obs indicate a few light sprinkles moving through, but these are not producing any significant rainfall. Temperatures along the island chain are falling through the mid to upper 60s, and winds on land are from the northwest at 15 to 20 mph. Surface analysis depicts low pressure east of the North Carolina Outer Banks, and high pressure centered over the Northern Plains and extending southward to Texas. The Keys lie within moderate northwest flow between these features. Aloft, water vapor imagery shows an intense mid level cyclone moving eastward through the eastern Carolinas, with the base of the associated trough axis near the Keys and South Florida. The 00Z Key West sounding reflected a dry post-frontal airmass, with a strong inversion based near 4000 feet and a very dry profile above the inversion, with PW of 0.71 inches. MIMIC-TPW imagery shows an even drier airmass, with estimated PW values as low as a half inch, spreading SE through the eastern Gulf toward the Keys. Overnight, expect the large area of stratocu upstream of the Keys over the eastern Gulf to continue spreading across our area, as NW low level flow persists. This will provide partly to mostly cloudy skies. Temperatures will have a hard time dropping below the lower 60s in the Lower Keys due to the relatively warmer waters of the SE Gulf, but should drop into the mid/upper 50s to near 60 further up the island chain, where the low level flow will be coming off the mainland with just a short trajectory over Florida Bay. The existing forecast appears to be in good shape, and no updates are planned for this evening. && .MARINE... Evening observations from along the reef and at Smith Shoal Light show NW winds running in the low end of Small Craft Exercise Caution (SCEC) range, generally 15 to 17 knots. Winds will probably increase slightly during the next several hours, possibly reaching 20 knots at times, but overall expect SCEC conditions to continue through the rest of the night. The exception will be across the offshore Gulf waters and Lower Straits of Florida, where NW swell will bring seas up above 7 feet, requiring Small Craft Advisory headlines for those areas. No significant changes are planned for the late evening forecast issuance. && .AVIATION... VFR conditions will prevail at the EYW and MTH terminals overnight and Saturday. Other that a few light sprinkles through late this evening, dry weather is expected. Periods of ceilings between 4000 and 5000 feet will continue through Saturday morning as stratocu streams in from the Gulf of Mexico. Skies should clear out during the late morning into the afternoon hours as the low level flow turns to the north, with MTH likely clearing a few hours earlier than EYW. Surface winds will remain from the NW at 10 to 15 knots with gusts to 20 knots overnight, gradually veering to the N and decreasing on Saturday. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...Small Craft Advisory for GMZ033-034-055-075. && $$ Public/Marine/Fire...Jacobson Aviation/Nowcasts....Jacobson Data Acquisition.....JAM Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest