Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 140145
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
945 PM EDT Wed Aug 13 2014
.Near Term [Through Tonight]...
00z surface analysis indicated a cold front stretching across the
forecast area from near Albany through far southestern Alabama and
into the Florida Panhandle. The front separates a much drier
airmass (dewpoints in the 50s across northern AL/GA) from the
juicy airmass across most of Florida (PWAT still at or above 2
inches). Regional radar composite continues to show isolated
showers along and just south of the frontal boundary. Expect this
activity to fade out by midnight. Thereafter, additional
convection is expected to fire over the coastal waters late
tonight, with increased rain chances along the coast, especially
east of Panama City Beach. Made a few minor adjustments to the PoP
grids for the evening and overnight periods, but no major changes.
[Through 00Z Friday] Drier air behind a weak cold front has
already moved into the DHN and ABY terminals. These sites will
have a reduced chance for low cigs and fog overnight and a very
low chance for convection on Thursday. However, situated in the
more moist environment, ECP, TLH, and VLD should once again see
MVFR conditions in the early morning hours due to the development
of low cigs and patchy fog. Expect skies to scatter out by mid to
late Thursday morning with sct to numerous Tstms developing by
afternoon. Winds will remain light even behind the front.
.Prev Discussion [333 PM EDT]...
.Short Term [Thursday Through Friday Night]...
The synoptic-scale features on Thursday should be fairly similar
to 24 hours prior, with a stalled surface front situated over the
northwest half of our forecast area. Deep layer drying in the wake
of the front should leave precipitable water values well below
normal in those areas, reducing rain chances considerably. To the
southeast of the front, deep moisture will linger with PWATs above
2 inches. Earlier model guidance suggested high PoPs and strong
potential for heavy rain. However, 12Z guidance - both global and
high-resolution - has backed off that notion somewhat. However,
given the moist environment, a larger-scale forcing mechanism (the
stalled front), and very slow storm motions of 5-15 knots, we
still think there is a risk for locally heavy rain and flooding in
the Florida Big Bend into Thursday. 60-70% ("likely") PoPs were
included in the Big Bend region on Thursday along with heavy rain
wording in the forecast. A Flash Flood Watch was considered, but
at this time confidence in rainfall rates sufficient to trigger
flash flooding is too low. Highs on Thursday should be in the mid-
90s further north where mostly sunny skies and only sporadic
convection is expected, with highs closer to 90 in the Big Bend.
On Friday, the deeper dry air aloft will advect further into the
area and reduce PoPs further. The surface front will remain
stalled in the vicinity, though, so isolated to scattered showers
and storms are still possible. Highs should be more uniform in the
low-mid 90s across the area. Lows both mornings should be in the
low 70s - close to seasonal normals.
.Long Term [Saturday Through Wednesday]...
The driest day - in terms of lowest rain chances - should be on
Saturday when the SREF mean PWATs fall below 1.7" across most of
the forecast area. That is the 25th percentile at TLH for August.
Deeper moisture should return on Sunday and into early next week
as southwest flow develops once again in the low-mid levels. From
Sunday to Wednesday, the forecast calls for scattered
thunderstorms, highs in the low-mid 90s and lows in the mid 70s.
Showers and thunderstorms should be fairly widespread over the
coastal waters for the next couple mornings, especially Thursday
morning. Winds and seas could be higher near the storms.
Otherwise, the forecast calls for winds of 10 knots or less and
seas of 2 feet or less through the weekend.
Although there will be significantly drier air over northern
portions of the Tri-State area than to the south, conditions will
not approach red flag levels anywhere across the region over the
next several days.
There is still a risk of heavy rainfall and localized flooding in
the Florida Big Bend through Thursday evening. While average
rainfall totals during that timeframe should generally be around 1
inch in the Big Bend region, isolated amounts of over 4 inches
will be possible. That amount of rain falling in a short period of
time could produce some flooding in urban areas, low-lying spots,
or in small basins and streams. The risk of flooding is much lower
on main-stem rivers and outside of the immediate Florida Big Bend.
.Preliminary Point Temps/PoPs...
Tallahassee 74 93 72 94 73 / 30 70 30 40 30
Panama City 76 90 76 91 76 / 30 30 20 30 20
Dothan 69 94 70 94 71 / 10 10 10 20 10
Albany 70 94 70 94 71 / 10 20 10 20 10
Valdosta 73 92 71 93 70 / 20 70 40 40 30
Cross City 75 90 73 91 71 / 50 60 40 50 30
Apalachicola 77 89 76 91 77 / 50 50 30 50 20