Area Forecast Discussion
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479
FXUS62 KTAE 131933
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
333 PM EDT Wed Aug 13 2014

.Near Term [Through Tonight]...

More concentrated convective activity, associated with early
morning development over the Gulf of Mexico, has progressed mostly
east of the Suwannee River as of 19Z. Meanwhile, a stalling
surface front was situated from Destin FL, to Bainbridge GA, to
Fitzgerald GA (DTS-BGE-FZG). A few other isolated thunderstorms
were developing in the unstable environment southeast of the
front, and this may continue through the late afternoon and early
evening. Convection-allowing models (CAM) are in fairly good
agreement now in showing mostly isolated-scattered coverage
through mid-evening over land and southeast of the front. After
around 03-05Z, convection should become focused once again over
the Gulf of Mexico and increase in coverage after 07-08Z. Lows
should be mostly in the low-mid 70s, although a few 60s are
possible in the far northwest sections of the forecast area where
a drier air mass will be located.


.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.

&&

.Aviation...

[Through 18Z Thursday] There is a chance for showers and
thunderstorms this afternoon/evening mainly for TLH, VLD and ECP
as a stalling cold front lingers just west of these terminals.
TLH, VLD and ECP will have MVFR conditions in the early morning
hours as a low ceiling forms due to radiational cooling. Expect
skies to scatter out late Thursday morning. Winds will remain
light even behind the front.

&&

.Marine...

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.

&&

.Fire Weather...

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.

&&

.Hydrology...

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 /  30  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

&&

.TAE Watches/Warnings/Advisories...

FL...None.
GA...None.
AL...None.
GM...None.

&&

$$

NEAR TERM...LAMERS
SHORT TERM...LAMERS
LONG TERM...LAMERS
AVIATION...MCDERMOTT
MARINE...LAMERS
FIRE WEATHER...GOULD
HYDROLOGY...LAMERS






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