529 FXUS62 KKEY 092042 AFDKEY Area Forecast Discussion National Weather Service Key West FL 342 PM EST Sat Mar 9 2019 .DISCUSSION...In the middle and upper levels(700-200 mb), latest available satellite imagery overlaid with model streamline analysis depict a developing negatively tilted trough oriented from Northeastern Montana southeastward to the Mid-Mississippi Valley. South of that, a nearly zonal southern stream of the jet is moving across the Eastern Pacific, Mexico, the Gulf of Mexico to across Florida. At the surface and in the lower to mid levels(Surface to 700 mb), latest available marine and land surface observations and analysis detail strong low pressure over Kansas swinging a cold front south to the Texas Big Bend Region. East of that, the axis of a near 1030 mb cold high pressure surface ridge is oriented from the Adirondacks south to the Delmarva Peninsula. .CURRENTLY...As of 300 pm, skies are mostly sunny across the islands and surrounding waters. There are only one or two very small showers out in the Florida Straits just off of Layton and Windley Key. Temperatures today have reached the lower 80s thus farm with dewpoints in the upper 60s to around 70. C-man stations along the Florida Reef are recording Southeast winds between 10 and 15 knots, and 10 to 15 mph over the islands. .SHORT TERM...Tonight thru Tuesday, temperatures and humidity levels will continue above normal through the period. As the aforementioned trough over the Upper Plains/Midwest migrates eastward it will gradually lift out through the rest of the weekend and into early next week. At our latitude the more zonal middle and upper level flow will become weaker again as a 590-595 dm plus ridge at 500 mb forms over the Central Gulf Sunday, expanding eastwards towards South Florida and the Keys thru Tuesday. The attendant southwestern edge of surface ridging centered over the North Central Atlantic will remain across Central Florida tonight thru Tuesday, with only a gentle to occasionally moderate pressure gradient in place. Latest available forecast soundings illustrate PWAT remains around 1.00 inches until Monday when it rises only to between 1.00 and 1.25 inches thru Tuesday. Hence will keep out chances for any measurable rainfall over the islands tonight thru tomorrow night, but insert a dime pop, 10%, in for Monday thru Tuesday, given above normal temperatures and enough moisture to trigger only a very isolated shower late at night/early in the am Monday thru Tuesday. Highs and lows will continue a few degrees above normal for late winter, mid 80s and mid 70s respectively. && .LONG TERM...Tuesday thru Saturday, South Florida and the Keys will remain beneath the northern periphery of deep ridging at 500 mb, averaging near 590 dm. During Monday, a weakening surface trough/feeble frontal boundary will attempt to move southwards down the Peninsula, stalling out somewhere over Central/South Florida Monday Night thru Tuesday. Very little moisture/weak surface convergence ahead of this boundary is only supportive of a slight chance for showers, 10%, in the grids Tuesday and Tuesday Night. Also during Tuesday Night, another very strong surface anticyclone over the Northeastern United States will build southwards down into the Carolinas, with breezy conditions resulting from Wednesday thru Thursday, before the ridge pulls far enough eastward Thursday night thru Saturday, resulting in lessening and veering southeast winds across the Keys for that period. Temperatures will continue near or slightly above normal. Given the near breezy/breezy conditions resulting from the typical MSLP gradient, expect sufficient near surface convergence to allow for very isolated showers, again mainly late at night and early in the morning. As such, a dime pop is in the grids thru the entire period, but these showers will be very few and far between as sky conditions will average mostly sunny/mostly clear thru the period. && .MARINE...No SCEC or SCA expected tonight thru Tuesday Night, although winds may surge again to near 15 knots in the Florida Straits and Hawk Channel later this evening and tonight. SCEC and SCA conditions will return across all waters for Wednesday thru at least Thursday. Winds and seas will let down again a bit Thursday night. && .AVIATION...Tonight, VFR conditions expected at the KEYW and KMTH island terminals tonight averaging 9-12 knots from between 100-120 degrees with some gusts between 15 and 20 knots. && .PRELIMINARY POINT TEMPS/POPS... Key West 76 85 76 84 / - - - 10 Marathon 77 87 77 86 / - - - 10 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...Futterman Aviation/Nowcasts....Chesser Upper Air/Data Collection......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