972
FXUS62 KTAE 201514
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1114 AM EDT Mon May 20 2013

.DISCUSSION...
The 12 UTC regional surface analysis showed the western periphery
of the West Atlantic ridge across the Southeast. There appeared to
be an outflow boundary, leftover from Sunday`s thunderstorms in
GA, off the FL Panhandle coast. Visible satellite imagery showed a
well-defined MCV, again leftover from yesterday`s convective
complex, centered over Tallahassee. Vapor imagery and upper air
data showed a ridge axis from Mobile to Ohio, with a weak trough
over the Piedmont. Local radars were quiet so far. Assuming a
surface air parcel of about 90 deg with a dewpoint in the lower to
mid 60s, the SBCAPE at Tallahassee this afternoon would be about
1000 J/Kg.

The large scale environment suggests that the best combination of
deep layer moisture and Q-G forcing will be over our eastern
zones, which is where the statistical guidance consensus has our
highest PoP (30-40% PoP). The 00/06 UTC Convection Allowing Model
(CAM) consensus is on board with this scenario as well. However,
the latest HRRR and 11 UTC local WRF runs indicate more
widespread convection than this, mainly late this afternoon. To
account for this possibility we spread out the PoP more broadly
across our forecast area, with the highest PoP (40%) still being
across South Central GA and North FL.

Mid tropospheric lapse rates were rather high, and most of the
CAPE will be in within the hail growth zone. This suggests the
potential for pulse strong to marginally severe storms later
today, with dime to quarter size hail and microburst wind gusts
of 50 to 60 MPH possible. The weak winds throughout the lower to
mid troposphere will tend to inhibit significant storm
organization and/or updraft rotation, so the coverage and impacts
will be low...about a 5% probability of a severe storm within 25
miles of a point.

&&

.AVIATION [through 18 UTC Tuesday]...
Isolated to scattered TSRA will develop this afternoon, mainly
from 19 UTC through 24 UTC, and mainly around KABY and KVLD where
the probability is 40%. A few storms could produce strong to
severe wind gusts and/or marginally severe hail. The probability
of TSRA elsewhere is 30% or less. Outside of TSRA, VFR vis and
cigs are expected. Patchy fog and/or low clouds are possible for a
brief time Tuesday morning, though confidence is not high enough
to explicitly mention in this TAF package.

&&

.HYDROLOGY...
Only scattered showers and thunderstorms are anticipated over the
next couple of afternoons, and will primarily be confined to areas
east of a line from Tallahassee north to Albany. With weak
steering flow, any storms that do form will have the potential to
meander very slowly or propagate along boundaries. For that
reason, there will remain the potential for isolated nuisance
flooding, but this will have little to no impact on area rivers
and streams.

&&

.PRELIMINARY POINT TEMPS/POPS...
Tallahassee   90  65  90  66 /  30  30  20  20
Panama City   83  68  84  70 /  20  20  20  10
Dothan        91  67  92  68 /  30  30  20  20
Albany        90  67  91  67 /  40  30  20  20
Valdosta      91  65  88  65 /  40  30  30  20
Cross City    88  65  88  65 /  30  30  40  20
Apalachicola  82  66  82  68 /  20  20  20  10

&&

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

&&

$$

HYDROLOGY...Harrigan
REST OF DISCUSSION...Fournier