Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 151407
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1007 AM EDT Fri Aug 15 2014
.Near Term [Through Today]...
Dry air continues to advect into the area, as indicated by the 12Z
Tallahassee sounding, particularly in the mid-levels of the
atmosphere. Precipitable water - a measure of the total amount of
water vapor in the troposphere - on the sounding has fallen to
1.53", which is about 80% of normal and below the 25th percentile
historically for August. In general during the summer months, it
is difficult to develop and sustain robust convection when PWATs
fall that low in the historical distribution. Therefore, we
continue to expect convective development this afternoon to be
suppressed over most of the area. However, the GOES blended total
PWAT product does indicate higher values - in excess of 1.8" - to
the southeast of the Aucilla River (the eastern Big Bend region).
30-50% PoPs have been outlined in this area of deeper moisture
that is also in relatively close proximity to a stalled surface
front. Isolated showers and thunderstorms (15-20% PoP) have been
included as far northwest as a Tyndall AFB - Thomasville - Alapaha
line (roughly PAM-TVI-DQH). Highs in the low-mid 90s look likely
again today with the limited cloud cover and rain.
.Long Term [Sunday Night Through Friday]...
Nearly zonal flow will gradually be replaced by building upper level
ridging across the SE U.S. through the entire extended period, while
a weak Sfc high pressure system generally remains in place across
the northern Gulf of Mexico. This type of synoptic pattern with
potential stacked ridging should result in a prolonged period of hot
and humid conditions across the entire CWA, with below normal PoPs
forced only by the diurnal sea breeze circulation. High temps should
at least be in the mid 90s away from the coast, with some upper 90s
certainly possible by mid to late week. Overnight lows will mainly
be in the very muggy mid to upper 70s.
.Prev Discussion [204 AM EDT]...
.Short Term [Tonight Through Sunday]...
The GFS and ECMWF are in good agreement in building an east-west
oriented deep layer ridge across the FL Peninsula and eastern
Gulf of Mexico. What`s left of the quasi-stationary front
(currently across our forecast area) will drift very slowly to the
north and gradually dissipate. Both global models forecast dry,
sinking air aloft on Saturday- especially along and north of a
line from Panama City to Valdosta (where our forecast PoP is 20%
or less in the afternoon & evening hours). It won`t be quite as
dry across north FL, and the boundary layer will still be very
moist, so scattered storms are expected (30% PoP). Deep layer
moisture will begin to gradually increase from southwest to
northeast on Sunday, though there will still be some residual
warm/dry air aloft. The forecast PoP is 20-30%, though with the
weakening front we don`t expect to see as sharp a difference in
the moisture/PoP distribution. Highs temperatures will be in the
mid 90s inland (around 90 at the coast), and lows will be in the
[Through 06Z Saturday] MVFR to IFR visibilities are expected once
again this morning at TLH and VLD. Shortly after sunrise, VFR will
return to all terminals. There is a relatively low chance of a
thunderstorm impacting TLH and VLD this afternoon, with
essentially no chance of rain at ECP, DHN, and ABY.
Winds will generally be west to southwest around 10 KT into early
next week, as a high pressure ridge builds across the Florida
Peninsula and eastern Gulf of Mexico. Seas will be 2 ft or less.
The Tri-State region will be bisected northeast to southwest for a
couple more days by a front dividing dry air to the north and more
saturated conditions to the south. However, even in the driest
locations relative humidity levels should remain above critical
levels precluding any hazardous fire weather conditions.
Through Saturday we expect the heaviest rain around Cross City and
Mayo, where 0.50 to 1 inch is likely. Locally heavy rain is
possible, which could cause brief, localized flooding of low-lying
urban areas. Elsewhere the showers & storms will be too isolated to
make a significant dent in our summer dry spell, and area rivers
remain well below flood stage.
.Preliminary Point Temps/PoPs...
Tallahassee 95 73 93 73 95 / 20 10 10 10 30
Panama City 90 76 90 77 90 / 20 10 10 10 30
Dothan 93 70 94 73 94 / 10 0 10 10 20
Albany 94 70 96 72 94 / 10 0 10 10 20
Valdosta 95 71 95 71 95 / 30 20 20 20 20
Cross City 89 73 91 72 93 / 40 30 30 20 20
Apalachicola 88 77 90 77 90 / 30 20 20 10 30