Area Forecast Discussion
Issued by NWS
FXUS62 KKEY 241859
Area Forecast Discussion
National Weather Service Key West FL
259 PM EDT SUN JUL 24 2016
Currently - A mid and upper cut off low is migrating westward across
the southern portion of the Florida Peninsula. This low has
contributed to highly variable weather through the day. The mornings
round of widespread rain with embedded thunderstorms has long since
dissipated, with only a few thunderstorms remaining over the Florida
Straits. The bulk of the activity is now located beyond our forecast
area, over the Florida Peninsula and the extreme southeastern Gulf of
Mexico. Continued near overcast conditions have kept highs in the mid
80s with dew points suppressed in the low to mid 70s. Surface winds,
away from convectively disturbed areas, are generally light out of
the east to southeast.
Forecast - The mid to upper level low will continue shifting
westward into the Gulf of Mexico this evening. Until the low departs
our area, we will be under a regime of cyclonic flow that reaches
down to the 850 mb level and ample deep layered moisture. This is
in addition the usually unstable environment we have this time of
year. There is a good chance for another round or two of showers and
thunderstorms across the Florida Keys. One trigger will be outflow
boundaries emanating off of South Florida into the Florida Keys and
our own collection of boundaries. Another trigger will be the
usually more convective eastern semicircle of an upper level low.
Expect overnight lows to range in the upper 70s mainly due to rain
With the eventual departure of the upper level low, deep layered
Atlantic ridging will begin building westward across Florida. As a
result, surface winds will edge upwards a bit. In addition, a slug of
drier and warmer low level air will move in bringing with it a more
inhospitable environment for shower development. Will maintain slight
chance pops for the Monday night and Tuesday time frame. Thereafter,
the lower levels moisten and cool, returning the Keys to a more
seasonable low chance for rain. Expect little trend in temperatures
through the duration of the forecast.
A broad high remains across the Florida Peninsula. Aside from
convectively disturbed areas, this ridge is keeping winds light out
of the east to southeast on Florida Keys waters. Winds are expected
to edge upwards through the first half of the week as a stronger
ridge builds westward across the Florida Peninsula. While advisories
are not expected, a period or two of cautions may be required for the
Florida Straits around mid week.
Activity from this morning has diminished. Will have VCSH in the
TAFs beginning 21Z for the possibility of redevelopment across the
area. Thunderstorms could impact the terminals tonight/Monday
morning. Will do short term amendments to add TEMPOs if needed due
to uncertainty on timing. Impacts will last up to 1-2 hours. Primary
impacts include lightning...brief wind gusts 25-30 knots...
visibilities of 1-3SM...and ceilings of 2000-2500 feet.
Outside of thunderstorm activity winds will be very light.
.PRELIMINARY POINT TEMPS/POPS...
Key West 78 89 81 89 / 50 30 20 20
Marathon 78 92 81 92 / 50 30 20 20
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