Severe Thunderstorm Warning 257, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
304 AM EDT Fri Oct 3 2014

.Near Term [Through Tonight]...
A broad long wave trough dominates much of North America this
morning. One potent short wave is lifting northeastward across the
Mid Mississippi Valley early this morning. Additional energy over
the Northern high plains will kick the lead system quickly
northeastward, while maintaining the amplitude of the larger scale
trough which will take on a slight negative tilt today. The cold
front associated with this system is analyzed from the Great Lakes
southwestward across the Mid Mississippi Valley to the TX Gulf
Coast at 06Z. A squall line extends ahead of the front from
Southwest IN south to Northwest AL and then southwest to South TX.
The front will sweep across our forecast area tonight, reaching
Coffee County in Southeast AL by around 00Z and then passing
southeast of Dixie County FL by about 09Z.

Scattered to numerous thunderstorms will develop ahead of the
front this morning across our western zones and then work their
way eastward across the rest of the forecast area this afternoon.
Another broken line of storms forced directly by the front will
cross the area this evening. Shear profiles still look to be too
weak to support organized severe weather across our forecast area
today as the most energetic part of this system will be north of
the region. That said, isolated strong to severe storms cannot be
ruled out anywhere in the forecast area this afternoon. SPC does
have our Southeast AL and northern tier GA zones in a 5% risk area
for severe storms, the primary threat being damaging straight line
winds.

Today will be warm and quite muggy by October standards. Highs will
be in the mid to upper 80s with afternoon dew points in the lower
70s. Peak heat indices will be in the mid 90s along and south of
I-10. Much cooler and drier air will follow frontal passage with
the northwestern half of the forecast area dropping into the 50s
overnight.

.Short Term [Saturday Through Sunday]...
The front will have cleared the area by Saturday with dry weather
for the weekend. The main forecast challenge will be temperatures,
as we will likely be seeing our coolest readings since last April
on Saturday night. The MOS guidance is quite chilly indeed with
mainly low to mid 40s across the area. However, that will depend
heavily on whether the surface high ends up directly overhead with
calm winds or remains just west of the area. It may remain
centered just west of the area, so the official forecast went a
couple of degrees above MOS by blending in a little of the raw
model guidance as well. This leads to mainly middle 40s inland and
lower 50s near the coast. Daytime highs will mainly be in the 70s,
except for a few leftover lower 80s in the southeast big bend on
Saturday.

.Long Term [Sunday Night Through Friday]...
High pressure at the surface will remain in place across the
region into Monday as the mid and upper level trough amplifies
across the Eastern CONUS. Return flow from the Gulf intensifies on
Tuesday ahead of a weak frontal system moving through the Ohio
and Tennessee River Valleys. There is a good amount of
disagreement between the GFS/Euro at this time frame and beyond
with how amplified the East CONUS trough becomes. The latest Euro
solution would seem to suggest a stronger solution with greater
rain chances for our region on Tuesday with another frontal
passage. The GFS (and to some extent with the Canadian) support a
less energetic solution for Tuesday. For now, will trend the
forecast toward a less energetic (and not as wet) Tuesday. Drier
weather should return by Thursday as high pressure builds off the
Mid Atlantic Coast.

&&

.Aviation...
[Through 06Z Saturday] VFR conditions will start the period.
However, MVFR ceilings and visibilities are expected to develop
after 08-09Z. ABY and VLD could see a period of IFR as well.
Convection will develop during the morning hours and become more
widespread during the afternoon hours. Another round of storms
will accompany a cold front which will cross the forecast area
from northwest to southeast this evening.

&&

.Marine...
Southwesterly flow will gradually increase today ahead of an
approaching cold front and shift to offshore tonight as the front
moves through. Solid cautionary conditions are expected overnight
across the entire area with a period of advisory level winds
possible, mainly west of Apalachicola. Winds are expected to
remain near caution levels for Saturday with a decreasing trend
for Sunday.

&&

.Fire Weather...
Relative humidities will dip into the mid to upper 20 percent
range this weekend for all but the Valdosta region and the
southeast big bend. Minimum relative humidities in these areas
will be in the lower to mid 30 percent range. It continues to look
like the southeast Alabama area will be borderline for red flag
conditions on Saturday afternoon, so the watch will remain in
place for now. In Georgia, relative humidities may dip below 25
percent in some locations, but the wind and 10-hour fuel moisture
requirement will not reach Red Flag conditions. The Florida
panhandle and western big bend zones should meet the minimum
relative humidity requirement for both Saturday and Sunday, but
the ERC values are currently expected to remain below red flag
criteria.

&&

.Hydrology...
Although some of the stronger storms today could produce locally
heavy rainfall in excess of 2", most areas should receive average
totals of 1" or less due to the fast moving nature of the
approaching cold front. This amount of rainfall will have little
impact on our area rivers and streams.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   87  64  78  47  76 /  70  60   0   0   0
Panama City   86  64  76  53  76 /  70  50   0   0   0
Dothan        86  55  71  44  75 /  70  40   0   0   0
Albany        86  58  73  45  74 /  70  50   0   0   0
Valdosta      86  63  77  46  73 /  60  60   0   0   0
Cross City    87  70  82  50  75 /  50  50  10   0   0
Apalachicola  85  65  79  53  75 /  60  60   0   0   0

&&

.TAE Watches/Warnings/Advisories...

FL...None.
GA...None.
AL...Fire Weather Watch from Saturday afternoon through Saturday
     evening for Coffee-Dale-Geneva-Henry-Houston.

GM...None.

&&

NEAR TERM...WOOL
SHORT TERM...DVD
LONG TERM...GODSEY
AVIATION...WOOL
MARINE...DVD
FIRE WEATHER...DVD
HYDROLOGY...WOOL