Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 031500
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1000 AM EST Mon Mar 3 2014
.Near Term [Through Today]...
A shortwave trough moving through the Tennessee Valley presents
itself very well via WV imagery this morning. It appears as though
this wave never really phased with the frontal system overnight,
and with the surface low pulling northeast, there has been a
gradual weakening trend to the convection along the front. As the
impressive looking shortwave continues its track eastward it will
force a large swath of mid-level dry air over the low-level front.
Although the line of showers is breaking up as it enters the Tri-
State region this morning, increased surface based instability
associated with diurnal heating, and some limited mid/upper level
jet support should reorganize convection a bit by early this
afternoon. However, the aforementioned mid-level dry air should
cap any storms that try to get going along the front, limiting
activity to rather shallow showers.
Still expected a rather stark temperature gradient across the
region today, with middle 70s from Tallahassee to Valdosta and
locations southeast. To the northwest, low to middle 60s will be
[Through 12Z Tuesday]...
With the exception of KVLD, all terminals have reached at least
MVFR restrictions this morning. As a broken line of showers moves
east, expect ceilings to remain MVFR along the line, while likely
scattering to VFR ahead of and behind the front.
.Prev Discussion [621 AM EST]...
.Short Term [Tonight Through Wednesday]...
The GFS and ECMWF are in good agreement in forecasting a fast
500 mb flow pattern over the CONUS. From today through Thursday, the
average return period of a trough in our forecast area is about 36
hours. The rain will end quickly in North FL this evening as cooler,
much drier air advects into the region. However, the truly cold air
will remain well to the north, making a freeze unlikely (less than
20% chance) in our northwest zones. Patchy frost is possible there,
however. Lows will range from the mid 30s, to around 50 at Cross
City. Clouds will increase during the day on Wednesday as the next
trough approaches over the central Gulf Coast. With the increase in
clouds and a shallow cool airmass in place, highs will be rather
chilly (only lower to mid 50s) in GA and Al. Highs in FL will range
from the upper 50s (north and west of Tallahassee) to upper 60s
(around Cross City). The aforementioned trough will race east over
our region Tuesday night, bringing a chance of mostly light rain.
Lows will be in the upper 30s (north) to upper 40s south.
The forecast for Wednesday becomes more tricky due to detail
differences between the GFS and ECMWF. The GFS forecasts a temporary
dry period (between troughs), while the ECMWF continues the rain on
Wednesday. As is often the case with this type of forecast
divergence, we took an average of the two solutions, and forecast a
chance of rain (30-40%), mainly during the afternoon. Highs will
range from the lower 60s north to around 70 at Cross City.
.Long Term [Wednesday Night Through Monday]...
The main focus will be Thursday, when the next trough is scheduled
to move through our area. The GFS and ECMWF have come into much
better agreement with this system. Although it will be rather
impressive in terms of 500 mb height falls, neither model forecasts
the unusually strong surface cyclogenesis hinted at in previous
runs. The mean of the MSLP from all of the available NWP guidance
indicates an "average" intensity cyclone moving northeast across
North FL Thursday morning. Such a track would put all, or nearly
all, of our forecast area in the cool sector, greatly limiting the
threat of severe storms. The long term discussion issued later today
will address the remainder of the forecast period.
South winds around 10 KT this morning will shift to the northwest at
15 to 20 KT behind the cold front this afternoon, mainly over the
Panhandle coastal waters. Winds will become north around 15 KT over
the entire coastal waters overnight. Winds will be northeast to east
10 to 15 KT Tuesday and Wednesday.
Red flag conditions are unlikely this week. Showers are expected
across most of the area today as a cold front moves through,
although rainfall amounts will be light. Drier air is expected for
Tuesday, but RH will remain well above red flag levels. Rain chances
will increase significantly again by the middle of the week.
Although several rivers still exhibited above-normal stage/flow,
those that were recently at flood stage were continuing to decline.
Today`s basin average rainfall totals will be less than a quarter of
an inch, which should not have much of an impact. The QPF for
Tuesday night/early Wednesday will likely be even less. The GFS and
ECMWF have backed off on the QPF for Thursday`s system, and we now
think that basin average values will generally be less than one
inch. The latest GFS ensemble-based hydro forecast (MMEFS) does not
forecast any of our rivers to reach flood stage this week.
.Preliminary Point Temps/PoPs...
Tallahassee 75 43 62 44 64 / 60 10 10 30 30
Panama City 67 42 59 47 62 / 60 10 10 40 40
Dothan 64 36 54 41 64 / 70 0 20 40 20
Albany 66 38 54 38 62 / 70 10 10 40 20
Valdosta 75 41 58 42 62 / 50 10 10 30 30
Cross City 73 50 69 48 70 / 40 20 10 30 30
Apalachicola 69 43 61 48 62 / 50 10 10 30 40
GM...Dense Fog Advisory until 1 PM EST this afternoon for Apalachee
Bay-Coastal waters From Ochlockonee River to Apalachicola
FL out to 20 NM-Coastal waters from Suwannee River to
Keaton Beach FL out 20 NM-Waters from Suwannee River to
Apalachicola FL from 20 to 60 NM.