Area Forecast Discussion
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FXUS62 KKEY 191840

Area Forecast Discussion
National Weather Service Key West FL
240 PM EDT Tue Sep 19 2017

.DISCUSSION...Dry and warm weather will persist through Wednesday
night with slightly above normal temperatures. A return to more
seasonable weather will begin Thursday with shower and thunderstorm
chances increasing into the weekend. Winds will generally be
light from the north to northeast today, becoming light tonight.
Stronger northeast trade winds will return Wednesday night.

.CURRENTLY...Dry weather with scattered clouds and mostly light
winds will prevail through the day. Winds will increase later this
afternoon and most areas will see northwest to northeast winds.

.SHORT TERM...Today through Friday. A weak pressure pattern
combined with relatively dry air will make for continued quiet,
warm, and dry conditions across the Keys. Currently precipitable
water over the area is 1.2 to 1.3 inches, which won`t support much
in the way of convection, just shallow cumulus. Precipitable
water values will increase to around 1.5 inches Wednesday, but
this is still pretty dry. Increasing northeast trade winds will
return Wednesday night and continue into the weekend. However, it
takes a while for the moisture to re-enter the area, and
precipitable water values will remain around 1.5 inches Thursday
before increasing to around 2.0 inches Friday. Will keep it dry
through Wednesday, then slowly ramp up the POPs to slight chance
from the south Wednesday night into Thursday, then bring it into
the chance range Thursday night.

With the dry conditions, temperatures will remain slightly above
seasonable values through Wednesday, 89-92, with lows 79-81,
before trending down to near normal values with a slightly lower
diurnal range Friday.


.LONG TERM...Friday night through Monday. All eyes will be on
Hurricane Maria through the weekend, which at this time looks like
it will remain well east of the Keys. Please refer to latest
National Hurricane Center products for more information. Increasing
easterlies will advect tropical moisture associated with the
hurricane into the area, and the chance for showers and
thunderstorms will increase Friday night into Saturday. Maria will
be closest to the area Sunday, but guidance shows negative omega
and a drying/strengthening inversion, which suggests that the
Keys will be within the subsidence region surrounding Maria. Thus
the Sunday to Monday period looks to be drier again with slightly
warmer temperatures.


.MARINE...A weak pressure gradient will keep winds light and
variable into Wednesday night. Increasing northeast trade winds
will return Wednesday night and continue into the weekend.
Winds will increase to 10-15 kts Friday, and possibly as high as
20 kts Saturday, highest in the far eastern Straits of Florida.
Hurricane Maria is currently progged to pass east of the Bahamas
over the weekend, and as she lifts NE away from the area winds
will turn to the NW and ease into early next week.

Wave heights of generally 1-2 ft are expected through Friday, except
across the Straits of Florida where a continued long-period swell
sneaking through the Florida Channel will drive 2-4 ft seas, highest
east. As winds increase into the weekend significant seas will
likely rise an additional 1 ft all waters except within Florida Bay
and waters north of the Keys due to wave shadowing on the NE winds
off Southern Florida.


.AVIATION...VFR conditions will prevail at both KEYW & KMTH into
Wednesday. Surface winds will average from 290-310 degrees at
7-10 knots. There will be a few clouds with bases aoa FL025-030.





Data Collection......99

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