Area Forecast Discussion
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FXUS62 KKEY 260158

Area Forecast Discussion
National Weather Service Key West FL
958 PM EDT Thu May 25 2017

.DISCUSSION...In the middle and upper levels(700-200 mb), latest
available IR imagery overlaid with model streamline analysis as of
900 pm, detail the axis of a negatively tilted full latitude
trough oriented from Ontario southeast to off of the North
Carolina coast. The center of the middle and upper low pressure
had migrated far northeastward from 24 hours prior, and was over
Eastern Lake Erie, hence the base of the trough is now zonal flow
again across Florida and the Keys. Therefore, middle and upper
support has shifted well away from our area.

At the surface and in the lower to middle levels,(Surface to 700
mb), latest IR imagery overlaid with land and marine surface
observations and analysis as of 900 pm, detail A 996 mb low near
Atlantic City trailing the terminus of a decaying frontal
boundary down in our area in the Florida Straits. The 00Z evening
sounding still illustrated a very moist lower to mid troposphere
with Columnar PWAT still at 2.22 inches with variable winds up to
500 feet, becoming gentle to strong and southwesterly up to 500

.CURRENTLY...As of 900 pm, skies are mostly cloudy across the
entire service area with just isolated low and mid clouds, and
most of the coverage due to cirrus. Key West radar detects
isolated showers and a few thunderstorms across the Outer Florida
Straits beyond 45 nm south of the Keys Island Chain. C-man
stations along the Florida Reef are recording variable winds at 5
to 10 knots. Temperatures along the Florida Keys are in the
sultry lower to middle 80s with dewpoint temperatures in the upper

.SHORT TERM...Overnight, As mentioned above, middle and upper
levels have become zonal, but the column remains very moist and
unstable, with forecast soundings illustrating columnar PWAT
expected to remain between 1.75 and 2.00 inches thru 00Z
Saturday. Nevertheless, the Keys will remain just north of the
aforementioned stalled and decaying surface/low level boundary.
This will result in a light to gentle wind flow at the surface
tonight and Friday. That being said, there are still lots of small
scale leftover boundaries meandering about closer to the Keys, and
some of these boundaries will reignite closer to the Keys
overnight. Hence, have already shaved pops down to low
chance(30%) for tonight on an earlier update, and this is still
slightly above normal for this time of year.


.MARINE...Winds gave become variable and decreased markedly as the
waters are now in a weak pressure pattern just north of a trough.
Light and variable winds on Friday will gradually become mostly
east at 10 knots or less to begin this weekend. No headlines or
advisories anticipated.



Winds have turned light and variable this evening a few hours
earlier than expected, thus TAFs have been amended to reflect as
such.  Winds will remain light thru Friday, looking to favor a
northeasterly trajectory by afternoon. With drier air forecast to
filter in to the Keys area, expect rain chances to remain slight,
and as a result VFR conditions are expected to prevail at the Key
West and Marathon terminals.



On this date, back in the year 1995, the daily record warm low
temperature of 82F was recorded. This ties as the warmest low
temperature ever recorded in May. May 1995 went on to take the title
as the warmest May ever with an average temperature of 83.5F.
Temperature records in Key West date back to 1872.




Upper Air/Data Collection......DR

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