Area Forecast Discussion
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387
FXUS62 KKEY 241848
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
248 PM EDT Mon Jul 24 2017

.DISCUSSION...
Recent Doppler radar base reflectivity animations show a
decreasing trend in shower and thunderstorm coverage across the
Florida Keys and adjacent coastal waters, while coverage increases
over adjacent larger land masses (Cuba, Andros Island, Florida
Peninsula). A low-level ridge axis remains nearly stationary just
north of the Florida Keys, while a mid-level ridge axis remains
positioned just south of the Straits of Florida. Moist layer depth
has increased some during the last 24 hours according to both
satellite and sounding data, while a large-scale deep layer mean
subtropical anticyclone remains anchored over the western North
Atlantic. Large-scale vertical motion fields across the region are
weak or neutral. Moderate conditional instability, weak convective
inhibition, and plentiful boundary-layer moisture provide the
necessary ingredient for deep cumulus convection where low-level
lifting is available. The situation is fairly typical for late
July in the Keys, and our forecasts reflect this familiarity.

Our prognostic reasoning for this cycle is very consistent with
that articulated during the last several cycles. The mean position
of the deep layer anticyclone and associated ridge does not change
much during the next week. Therefore, daily rainfall patterns will
be modulated by subtle migratory impulses and associated moist
layer depth fluctuations within the weak east-southeasterly low-
level flow. Wind speeds should run generally below 15 knots
outside of showers and thunderstorms. An exception will be tonight
and Tuesday over the lower Straits of Florida where a few hours
with near 15-knot winds is possible.
&&

.MARINE...
No watches, warnings, or advisories are in effect for Florida Keys
coastal waters zones. A high pressure cell will extend westward
from the subtropical North Atlantic to the Gulf of Mexico from
tonight through through Saturday.
&&

.AVIATION...
VFR and gentle southeast breezes will prevail at the EYW and MTH
terminals this evening. This morning`s 12Z KKEY RAOB sampled
increased moisture throughout the column, and this trend likely will
continue tonight. Rain chances at both terminals appear to peak
after 09Z. Expect temporary periods of MVFR CIGS, IFR VIS, and
convective wind gusts near 25 knots within any shower impacts.
&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  83  91  83  91 / 30 30 30 30
Marathon  83  92  83  93 / 30 30 30 30
&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&

$$

Public/Marine/Fire...Kasper
Aviation/Nowcasts....CLR
Data Collection......Fling

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