503
FXUS62 KTAE 191528
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1128 AM EDT Sun May 19 2013

.DISCUSSION...
The 12 UTC regional surface analysis showed a ridge along
the Gulf Coast, and a decaying, quasi-stationary front from
southeast GA to MO. Vapor imagery and upper air data showed a
ridge axis from the MS coast to WI, and a weak trough over western
TN. There were already some clusters of thunderstorms over north
GA (producing frequent lightning strikes) associated with these
features, and the latest NWP guidance has these clusters (and/or
additional developing cells) translating south, then eventually eastward
later today along the aforementioned frontal boundary. Most of the
statistical and dynamical NWP guidance keeps the bulk of the rain
to our north and east, but some of the normally reliable
Convection Allowing Model (CAM) runs (including our 11 UTC local
WRF and the HRRR) manage to bring deep moist convection as far south
and west as the Dothan and the Tallahassee area later this
afternoon.

Our updated PoP forecast has a 40-50% PoP around Tifton, Valdosta,
and Albany, and a 20% PoP from Tallahassee to Dothan. Our local
"Confidence Grids" program shows a 5% probability of severe storms
(within 25 miles of point) in our GA zones, which is what the SPC
outlook shows as well. The CAM guidance also shows a small chance
of strong to severe storms in this region. Although the winds
throughout the lower and mid troposphere are weak (which should
limit the potential for significant storm organization/rotation),
the lapse rates aloft are steep enough to support a marginally
severe hail/damaging wind gust threat, in the form of "pulse"
storms (i.e. cells that quickly grow and decay). Any
showers/storms that develop elsewhere will be fighting poor thermodynamics,
as there was a warm/dry layer at 850 mb based on the KTAE sounding
from 12 UTC.

&&

.AVIATION...
Prevailing VFR conditions are expected until late tonight, when
another round of low cigs/fog is possible. Scattered SHRA/TSRA,
some possibly strong with gusty winds and/or hail, are expected
across south GA later this afternoon or early evening, and we may
need to update the KABY and KVLD TAFs at 18 UTC once it becomes
clearer as to how the storms currently in north GA are evolving.
Where it rains may also impact Monday morning`s fog/low cloud
forecast.

&&

.HYDROLOGY...
Area rivers and streams will remain well below flood stage for the
next several days with very little widespread rain in the forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
Tallahassee   89  64  90  66 /  20  20  20  10
Panama City   82  68  85  69 /  10  10  10  10
Dothan        89  66  92  66 /  20  10  10  10
Albany        89  66  91  66 /  50  20  20  20
Valdosta      91  64  92  65 /  40  30  30  20
Cross City    88  63  88  64 /  20  20  30  20
Apalachicola  81  66  84  68 /  10  10  10  10

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...NONE.

&&

$$

HYDROLOGY...Gould
REST OF DISCUSSION...Fournier