Area Forecast Discussion
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FXUS62 KKEY 191911

Area Forecast Discussion
National Weather Service Key West FL
311 PM EDT Thu Jul 19 2018

Just a few fair weather cumulus was noted over the larger islands
of the Keys this afternoon with temperatures in the lower 90s,
and heat index near 100F. The BYX radar has been free from rain
echoes since late morning.

Tonight through Saturday, the western extension of the low level
ridge slips remains essentially in place near the Keys and Straits
of Florida, with an upper trough across the eastern U.S. If
anything, a very gradual reduction of the Saharan Air Layer
influence is expected allowing for slight, but below
climatological rain chance into the weekend.

Sunday through Wednesday features a bit of a transition as the
eastern U.S. trough digs toward the eastern Gulf states, allowing
a deeper southerly flow to set up across the Keys. While southeast
to south winds will evolve above the surface, they appear to
remain quite light generally 10 knots at best. Precipitable water
climbs to near 2 inches in guidance, but cannot find remote
triggers other than second or third-generation outflow boundaries
from convection over Cuba, leeside Keys convection, or perhaps a
stray outflow boundary given the light flow eminating from the
mainland. Pops were bumped up above climatology as lapse rates
should be sufficient for convection by mid week, as well as a
slight acceleration of southeast to south winds possibly
increasing broad convergence through the area.

Thursday, a larger mid-level but "dirty" ridge appears to evolve
near or east of Florida. While low level moisture remains in
place, warming temperatures aloft appear to bring lapse rates
below 6.0C. Rain chance is forecast back to near average 30
percent with slightly less robust capability for updrafts from


No hazard headlines are expected in the Coastal Waters Forecasts
through at least Tuesday of next week. The presence of weak high
pressure ridging allows for mostly light southerly winds becoming
west to northwest each late afternoon. Perhaps slightly more solid
southerly winds may evolve by Tuesday, but likely to remain 10
knots or less.


Expect prevailing VFR at EYW & MTH through 20/18z. Southwesterly
flow will become light and variable overnight, with surface speeds
sustained near 7 knots becoming <5 knots until sunrise.


On this date in Keys Weather History, In 1930, the daily record cold
high temperature of 82 degrees was measured in Key West. Temperature
records for the city date back to 1871.


Key West  84  92  84  93 / 10 10 10 10
Marathon  82  94  84  94 / 10 10 10 10




Data Collection......DR

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