Area Forecast Discussion
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FXUS62 KKEY 230236

Area Forecast Discussion
National Weather Service Key West FL
1036 PM EDT Thu Aug 22 2019

The low-level subtropical ridge centered just southeast of Bermuda
reaches west across northern Florida. Nestled along the southern
flank of the ridge, just out of reach of the 20 to 25 knots of WNW
shear, is a broad area of low pressure pressing west away from
Andros. Radar loops reveal a distinct rotation between Andros and
the Upper Keys. Convection near the center of circulation has been
lack-luster, although the latest scans reveal a meager flurry of
thunderstorms. The shear which awaits this system as it lumbers
northwest will limit its ability to organize through the short-
term. See the Tropical section below for more details from the
NHC. Nevertheless, the cyclonic envelope will spread across the
island chain overnight, with the best chances for squalls and a
few thunderstorms across the Upper Keys. Winds at the reef tract
adjacent to the Upper Keys are higher than expected (10 to 15
knots) over the past few hours, so we have made adjustments
accordingly. No other changes are needed at this time.


No current watches, warnings, or advisories. The near-term
forecast (through the next 48 hours) will depend on the future
evolution of the disturbance near Andros Island. Winds will be
highly variable on Friday as the low pressure area slides
northwest through southern Florida. From synopsis, a broad area
of low pressure just west of Andros Island will move slowly
northwestward tonight and cross the Florida Keys and South Florida
Friday and Friday night. The trough is expected to lift northward
and away from our region Saturday and Saturday night. Thereafter,
a high pressure cell over Cuba will gradually lift northward into
the Straits of Florida, then into South Florida.


Widely scattered showers are moving towards the south and
southwest in the vicinity of the island chain. As such, have mention
of VCSH for both the EYW and MTH terminals for the overnight. VFR
conditions will be the prevailing conditions, though sub VFR
conditions are possible due to passing showers an possible
thunderstorms. Convection aside, winds will be light and primarily
out of the northeast.


Satellite and surface observations show that a broad area of
low pressure has formed just northwest of Andros Island in the
central Bahamas.  This system continues to produce a large area of
disorganized showers and thunderstorms that extend eastward over
the western Atlantic for a few hundred miles.  Environmental
conditions are forecast to be conducive for additional development
during the next several days, and a tropical depression could form
over the weekend or early next week while the system moves near the
coast of east-central Florida and then offshore of the southeast
United States coast.  Regardless of development, locally heavy rains
are possible over portions of the central and northwest Bahamas, and
the east-central and southeast Florida peninsula during the next few
days. Formation chance through 48 hours...low...30 percent. Formation
chance through 5 days...medium...50 percent.


Key West  81  89  81  89 / 40 50 40 50
Marathon  81  92  81  92 / 50 50 50 50




Data Collection......DR

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