Area Forecast Discussion
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FXUS62 KKEY 201929

Area Forecast Discussion
National Weather Service Key West FL
329 PM EDT Tue Mar 20 2018

A cold front is sliding down the Florida Peninsula, bringing
severe weather to northeast and central portions of the state.
Locally, skies are partly cloudy across the island chain, but
mostly clear offshore, and winds have shifted to the southwest in
response of the incoming system. Temperatures range from the upper
70s to mid 80s, and dew points remain in the low to mid 70s on
this first day of astronomical spring. Offshore, CMAN stations are
reporting wind speeds near 15 knots on average. The Pulley Ridge
Buoy in the southeastern gulf reports seas near 4 feet.

The cold front will begin reaching our western coastal zones this
evening, sweep across the island chain late tonight, and exit the
Straits of Florida tomorrow morning. Rain chances of 30 percent
have been maintained. Decent CAPE, combined with sfc-6km bulk
shear magnitude near 30 knots, and a decent low level moisture
(with overall PWAT near 1.4 inches), isolated thunderstorms will
remain a possibility... though the severe weather threat for land
(>60 mph wind gusts, 1 inch hail, or tornados) remains low.
Expect SW winds to increase while veering W, then NW by 12z
Wednesday. Cooler continental air will begin to filter into the
Keys tomorrow morning behind the front, with dew points dropping
into the 60s (and even 50s across the upper keys) by afternoon.


An extended period of dry weather and slightly below-normal
temperatures will return to the island chain as strong deep-
layered ridging builds across southeastern US and Central Gulf of
Mexico, and shifts eastward to the Florida peninsula late
week/early this weekend. Cool northerly breezes will persist until
the high pressure center shifts east of the Keys late weekend,
bringing a return to ESE flow and dew points gradually climbing
back into the upper 60s. In the extended forecast (early next
week), both the GFS and ECMWF are hinting at a `backdoor front`
sneaking near the island chain from the northeast, as a strong
cyclone deepens off the New England coast. Have brought showers
back into the forecast Monday through Tuesday night as a result.


Small craft should exercise caution in the offshore southeastern
gulf and Straits of Florida for increasing winds tonight. A cold
front will sweep through the Florida Keys and adjacent coastal
waters overnight. Thereafter, a continental high pressure cell
will migrate slowly eastward, across the Deep South, to the
western North Atlantic, between Wednesday and Saturday.


VFR conditions will continue at the KEYW and KMTH terminals early
this evening as low level winds remain sustained from the southwest
between 10 and 15 knots, occasionally gusting near 20 knots. A few
showers, with the potential for thunderstorms, are possible from
late this evening through the overnight hours. A VCSH from roughly
02z has been maintained at both locations for that reason. By early
Wednesday morning, winds will turn to the northwest, remaining
moderate with gusts aoa 20 knots into the afternoon.


On this date in 1936, the temperature in Key West dipped to 55
degrees. This set the daily low temperature record for March
twentieth in the city. Temperature records for Key West date back to


Key West  72  76  62  70 / 30 -  -  -
Marathon  71  76  59  70 / 30 -  -  -




Data Collection......Chesser

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