Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 120134
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
934 PM EDT Tue Mar 11 2014
.Near Term [Through Tonight]...
Upper disturbance over the Central Gulf Coast States will continue
to move eastward this evening. A large area of rain over the
northeastern Gulf will continue moving to the northeast ahead of
the disturbance and across our area this evening. While
instability is non-existent now, some weak instability could
materialize across the coastal waters with a few isolated
thunderstorms possible late tonight. Aside from that, expect most
of the forecast area to get some rain, with maximum amounts up to
0.75 inches by sunrise on Wednesday. Temperatures will be quite
warm overnight, generally in the lower 60s most areas due to all
the cloud cover and southerly flow.
.Aviation...[Through 00Z Thursday]...
MVFR cigs have overspread the area this eve from southwest to
northeast in association with showers. Although the rain should
clear Ern terminals by 09z-10Z Wednesday, low cigs may stick
around. Local hi-res guidance is showing vsbys in fog dropping to
IFR again around 10-14Z, this time across the entire forecast
area. Even after the BR clears, 3-5k cigs may stick around thru
sundown. South winds 5 to 10 kts overnight will veer to southwest
during the aftn and eve of Wednesday...and increase to 15 to 20
kts with higher gusts...except possibly at VLD.
.Prev Discussion [314 PM EDT]...
.Short Term [Wednesday Through Thursday Night]...
The rain will be ending from west to east Wednesday as the trough
axis moves off to our east. A fairly strong surface cold front will
move southeastward across our forecast area during the afternoon and
evening. With limited surface convergence along the front and
drying/subsidence aloft, rain chances along the front will be very
Although the airmass behind this cold front is rather cold for this
time of year, the bulk of the cold air will remain to our north and
west during the day. We prefer the warmest MOS temperatures (GFS
MOS) for our high temperature forecast, and our actually even a
little warmer than this guidance east of the Apalachicola River.
(Often during this time of year, when a cold front passes during the
afternoon, our temperatures tend to be warmer than MOS and well
above average). Although strong cold air advection will develop
Wednesday night, vertical mixing from non-zero wind speeds will
prevent a freeze. However, some sites north of Dothan and Tifton may
reach the mid 30s. With a shallow, cool airmass in place Thursday,
highs will be well below average- mid to upper 50s (north) to lower
60s (south). This may not seem very cold, but it becomes more
impressive considering there will be no clouds, and the incoming
solar radiation this time of year is quite strong (the vernal
equinox is just a little over one week away). A freeze appears more
likely Thursday night, as the MOS consensus is tightly clusters in
the lower 30s. This seems reasonable given the very low dew points
and surface high position (with calm winds).
.Long Term [Friday Through Tuesday]...
By Friday max temps will start to rebound into the 70s as an
approaching shortwave over northern Mexico propagates eastward.
Ahead of this mean southerly flow will prime the atmosphere for
another round of rain heading into the weekend. The GFS and EURO
both agree that the upper level pattern will divide into a split
stream with a positively tilted trough axis extending from Mexico
over the eastern CONUS. This will keep PoP chances up from Saturday
afternoon through Monday. Best chances for rain will be on Saturday,
with a 50-20% NW to SE gradient, thereafter chances will remain
30-40% for the entire CWA.
The NWP guidance forecasts a weak surface reflection (i.e. a trough)
developing in the northeast Gulf of Mexico tonight as the upper
level trough approaches quickly from the west. This will increase
the pressure gradient (and winds & seas) to moderate levels
overnight. Winds will gradually veer from southwest to west on
Wednesday as a large surface cyclone deepens over the Ohio Valley.
"Exercise Caution" conditions are expected Wednesday, but conditions
will deteriorate to advisory levels by Wednesday night once the cold
front moves through. Winds will be northwest to north at 20 to 25 KT
with gusts near gale force. Winds and seas will subside on Thursday
and Thursday night as an area of high pressure builds over the
Relative humidity values will drop to the 20s Thursday and Friday as
drier air moves in behind a cold front, however, 20 ft winds will
approach 15 MPH criteria Thursday, making for a borderline red flag
event, but will weaken by Friday. Over the weekend, relative
humidity will increase with the return of southerly flow and remain
above critical values through next Tuesday.
There were no rivers in flood stage. However, some rivers were
still above normal stage/flows. We expect about 0.50 inches of
rain overnight and Wednesday morning, which is not expected to
cause river flooding but will help keep river stage/flows above
normal. The latest MMEFS forecasts several points to be at action
stage over the next week or so, but none at flood stage.
.Preliminary Point Temps/PoPs...
Tallahassee 63 83 40 60 32 / 90 30 10 0 0
Panama City 63 75 40 59 40 / 90 20 10 0 0
Dothan 62 76 36 60 34 / 90 20 0 0 0
Albany 62 80 36 60 32 / 90 20 10 0 0
Valdosta 61 85 39 61 32 / 90 30 10 0 0
Cross City 63 83 40 63 31 / 80 40 10 0 0
Apalachicola 64 75 40 59 41 / 90 30 10 0 0