Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 191937
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
337 PM EDT Wed Jun 19 2013
.NEAR TERM [Through Tonight]...
Broad cyclonic flow continues across the Southeast U.S. A short wave
trough, remnants of yesterday`s TX MCV, is working its way eastward
across AL and was about to enter our forecast area at 19Z. A cold
front to our north continues to make very slow southward progress
and currently stretches east to west across central GA and AL. The
subtropical ridge axis remains suppressed to our south across the FL
Peninsula and central Gulf of Mexico. The KTAE 12 UTC sounding was
modified to reveal an afternoon CAPE of around 2400 J/kg.
Precipitable water has inched up to 1.62 inches and additional
moisture is expected to pool ahead of the slowly advancing frontal
boundary this afternoon. The sounding also shows that we remain in a
type 5 sea breeze regime with strong WSW flow through 700 mb. With
contributions from the synoptic scale and mesoscale lifting
mechanisms such as the sea breeze and outflow boundaries, we expect
higher than normal coverage of showers and storms today. Most of the
area now has a likely PoP (60%). Concerning the severe weather
threat, deep layer shear will hold near 30 kt in some areas as the
upper short wave moves over the area. Delta theta-e of 32-34
indicate a wet microburst potential. SPC has the area outlooked in a
5% risk area for damaging convective wind gusts. It now appears that
this threat will be limited to our northern zones closer to the
front and deeper moisture. As the short wave passes to our east, we
will lose that contribution to lift along with daytime instability.
However, the front is forecast to sag south into the forecast area.
We therefore maintained slight to low chance PoPs through the night.
Min temps will be close to seasonal norms in the lower 70s.
.SHORT TERM [Thursday through Friday Night]... A upper level
trough situated across most of the eastern seaboard will remain
the main controller of our weather pattern beginning of the short
term period. The associated surface low pressure is located just
offshore of the coastal Carolinas. Stemming from the surface low
is a stationary frontal boundary draped across our southern
Georgia counties. This frontal boundary will give an enhanced
chance for thunderstorms in the late afternoon hours keeping our
POPS in the 40-50% range. Although CAPE values are very marginal,
the equivalent potential temperature difference between the
surface and the 700-500 mb layer would suggest, if severe weather
were to occur, it would be damaging wind gusts. Severe hail does
not appear to be an issue with 500 mb temperatures being too warm.
Expect highs in the lower 90s during peak heating hours of the
afternoon and lows bottoming out in the lower 70s.
.LONG TERM [Saturday through Wednesday]...
A weak wave of low pressure diving southward cuts off, settling
over the western Florida panhandle. This will lead to an
unsettled weather pattern through Tuesday with afternoon PoPs
enhanced slightly to around 50%. By the end of the long term
period the Bermuda High will return our area to our usual
summertime pattern, with the main concern being afternoon sea
breeze storms. High temps will be in the lower 90s and low temps
will be in the lower 70s.
[Through 18 UTC Thursday] VFR conditions will prevail for this
afternoon. However, scattered thunderstorms may bring them briefly
back down into the MVFR category. We have removed prevailing MVFR
conditions for the early morning part of the forecast on Thursday,
except at ABY and VLD. Convection is expected to largely fire after
18 UTC on Thursday, so have not specified any in the TAFs.
As a frontal boundary to our north slowly inches south, a
localized tightening of the pressure gradient will allow for an
increase in winds this afternoon. Expect winds out the southwest
at 10-15 knots, mainly in our nearshore waters. This will allow
for a slight increase in seas around 2 to 3 feet. After the cold
front weakens, another ridge of high pressure will build to our
northeast keeping our CWA in a light E/SE flow and seas 1-2 feet.
Relative humidity values will remain above critical levels thus
precluding red flag conditions for the foreseeable future.
No problems are anticipated in the near future.
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 90 71 92 69 / 50 50 30 50 30
Panama City 74 91 75 89 74 / 40 50 30 40 20
Dothan 70 93 71 92 70 / 30 40 20 40 20
Albany 71 93 71 90 68 / 40 40 30 40 20
Valdosta 70 91 70 90 69 / 50 60 40 40 40
Cross City 71 92 71 91 69 / 40 50 30 40 30
Apalachicola 74 90 73 88 75 / 30 40 30 40 30
REST OF DISCUSSION...Harrigan/Navarro