Area Forecast Discussion
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957
FXUS62 KTAE 230755
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
255 AM EST Mon Feb 23 2015

...HEAVY RAINFALL EXPECTED ACROSS THE AREA ON WEDNESDAY WITH
THUNDERSTORMS POSSIBLE ACROSS THE SOUTHEAST BIG BEND...

.Near Term [Through Today]...
Zonal flow continues aloft with the only mentionable feature
locally being a weak southern stream +PV anomaly passing through
the Southeast today. At 07z this anomaly was placed, via WV
imagery, over the Mississippi River at the LA/AR/MS border. At the
surface, a quasi-stationary front is draped southwest to
northeast from the LA/MS coasts, through central AL & GA, up the
lee side of the Appalachians. Behind this front, is another front
delineating a moist airmass ahead of a strong surface ridge, from
the dry air behind it.

Through today, the southern stream anomaly will move east into the
western Atlantic, taking with it the large area of rain over the
Southeast this morning. However, the advancing surface ridge will
force the stationary boundary into motion, pushing it into the
southeast Big Bend by this evening.

Rain chances will be highest today across southeast Alabama and
southwest Georgia where the passing shortwave will have the
greatest impact locally. Then, as the front passes through the
Tri-State region, scattered light to moderate rain will accompany
it, though much of the area won`t have more than a 30% chance of
getting any measurable rain.

One last feature of note is an expected area of isentropic ascent
across the southeast Big Bend this morning through early
afternoon. Most of the hires guidance shows this feature while
the lower resolution models don`t quite pick up on it. This is
most likely because they are missing out on the shallow cool layer
over the Suwannee Valley this morning. The local hires guidance
seems to be handling the boundary layer quite well this morning
w.r.t. T, Td, and wind, so this forecast will bite on the
isentropic rain later this morning. Either way, it should be
fairly light as it is being forced primarily along the 290K
surface, and not much above that. Generally, rainfall amounts in
this area will be less than a tenth of an inch this morning.


.Short Term [Tonight Through Wednesday]...
The short term will be unsettled. A weak upper level disturbance
will bring an increase in moisture and light showers during the
day on Tuesday. Widespread cloud cover will also hold high
temperatures down into the 50s across most of the area for
Tuesday. The unsettled conditions will culminate on Wednesday as a
vigorous upper level shortwave crosses the region. A surface area
of low pressure is expected to develop somewhere near the coast
and track across our forecast area on Wednesday. This will likely
spread moderate to heavy rainfall across the area. Some
thunderstorms are also possible along and to the southeast of the
low track. The low has trended a little stronger and farther north
compared to earlier runs, so a chance of thunderstorms was
included across the southeast big bend. In fact, both the 00z GFS
and ECMWF have a 60 knot low level jet crossing the southeast big
bend on Wednesday evening with non-zero instability. There may be
a non-zero severe threat Wednesday afternoon and evening right
along the coast and into the southeast big bend depending on the
exact low track, although that threat looks more likely for the
coastal waters than the land area currently.


.Long Term [Wednesday Night Through Monday]...
The system will move out of the area on Wednesday night with dry
conditions expected to return for the remainder of the work week.
By the weekend, the 00z ECMWF has moisture returning while the
GFS is dry. The weekend forecast has shown a lot of variability
over the last couple of days. A slight chance of rain is shown for
both Saturday and Sunday with a warming trend back to the mid 60s
to near 70 for daytime highs on Sunday.

&&

.Aviation...
[Through 12z Tuesday] A mix of MVFR ceilings to LIFR ceilings and
visibilities exists across the region this morning. A front will
gradually move past DHN and possibly ABY and ECP this morning,
clearing out the LIFR visibilities, though IFR ceilings will
remain. By 14z all sites should be clear of restrictions in fog, a
ceilings will gradually raise through the day to VFR at all sites
by around 20z. Expect another round of low ceilings tonight.

&&

.Marine...
Light to moderate northerly winds will prevail today behind a cold
front. Winds and seas will increase again on Wednesday as an area
of low pressure moves near the coast with advisory conditions
likely. In fact, it could be rather stormy with gale force gusts
possible in addition to a squall line cross the area on Wednesday.
The low will move out of the area by Thursday with light to
moderate winds returning for the remainder of the week.

&&

.Fire Weather...
Hazardous fire weather conditions are not expected over the next
several days as a couple of rounds of rain will keep things quite
wet.

&&

.Hydrology...
An areawide moderate to heavy rain event is still expected on
Wednesday. Total rainfall is generally expected to be in the 2-3
inch range with isolated higher totals possible. This will cause
rises on area rivers and may bring a few of our sites back up to
action stage. At this time, flooding is not expected, although if
widespread rainfall amounts were to increase above 3 inches,
then the Kinchafoonee Creek as well as the Ochlockonee, Aucilla,
and Upper Withlacoochee Rivers could come close to minor flood
stage.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   65  49  56  46  55 /  20  60  60  40  90
Panama City   63  47  54  47  55 /  30  50  60  50  90
Dothan        58  42  51  42  48 /  50  60  60  40  90
Albany        59  42  51  41  50 /  60  60  60  30  90
Valdosta      65  47  52  44  53 /  30  60  60  40  90
Cross City    71  51  59  48  61 /  50  30  50  40  90
Apalachicola  68  51  57  50  60 /  20  30  50  50  90

&&

.TAE Watches/Warnings/Advisories...

FL...Dense Fog Advisory until 9 AM EST /8 AM CST/ this morning for
     Calhoun-Central Walton-Coastal Bay-Coastal Dixie-Coastal
     Franklin-Coastal Gulf-Coastal Jefferson-Coastal Taylor-
     Coastal Wakulla-Gadsden-Holmes-Inland Bay-Inland Dixie-
     Inland Franklin-Inland Gulf-Inland Jefferson-Inland Taylor-
     Inland Wakulla-Inland Walton-Jackson-Lafayette-Leon-Liberty-
     Madison-South Walton-Washington.

GA...Dense Fog Advisory until 9 AM EST this morning for Brooks-
     Decatur-Grady-Lowndes-Seminole-Thomas.

AL...None.
GM...None.

&&

$$

NEAR TERM...HARRIGAN
SHORT TERM...DVD
LONG TERM...DVD
AVIATION...HARRIGAN
MARINE...DVD
FIRE WEATHER...HARRIGAN
HYDROLOGY...DVD






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