Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 151943
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
343 PM EDT Sat Mar 15 2014
.Near Term [Through Tonight]...
Isentropic showers are beginning to dissipate across southeast
Alabama and the Florida Panhandle as low-level upslope flow
becomes more southerly and focuses along the Gulf coast near
Mobile. Another round of light showers will be possible across
southeast Alabama and the Florida Panhandle closer to dawn as a
mid-level PV anomaly advects quickly to the east away from ongoing
convection over southeast Texas, and brings a chance for some mid-
level isentropic ascent. Otherwise, organized convection should
hold off until tomorrow.
Overnight lows will range from the lower 50s south and east of a
line from Tallahassee to Valdosta, and the middle 50s to the west.
Coastal Panhandle communities will likely remain around 60 degrees.
.Short Term [Sunday Through Monday Night]...
An unsettled period of weather is set to begin on Sunday across
the region as a complex weather system moves across the
southeastern states. A large-scale trough is forecast to develop
over the Plains States tonight. A series of shortwaves will moves
through the mean trough and eject eastward across the forecast
area over the next two days. The first piece of energy will result
in cyclogenesis over Mississippi by Sunday morning, with the
surface low tracking eastward during the day. Deep layer southerly
to southwesterly flow will transport plenty of moisture into the
region with PWAT values approaching 1.75 inches (very high for
mid-March). Along with strong surface and mid-level flow, a 45-50
knot low-level jet will move into the western portion of the area
by late morning, and into the eastern half of the area during the
afternoon. Coupled with modest boundary layer instability
(500-1000 j/kg), severe thunderstorms will be possible. At this
time, guidance suggests a primarily linear mode, with damaging
straight-line winds being the primary threat as a squall line
pushes across the forecast area. However, with 0-1km shear values
approaching 35-40 knots, isolated tornadoes cannot be ruled out.
The primary squall line and severe weather threat is expected to
weaken with time Sunday evening over the far eastern zones, as the
instigating shortwave shears out to the northeast. However,
additional shorwave energy will move through the primary trough
axis Sunday night, inducing cyclogenesis over the eastern Gulf of
Mexico. While there is still some uncertainty over the speed of
the main trough, it does seem that rain chances will remain
elevated through much of the day on Monday, as deep layer moisture
remains in place and enhanced upper divergence associated with the
trough axis moves across the region. Fortunately, with Monday`s
surface low progged to track well south of the area, the region
will remain in the cool sector, limiting the risk for any
additional severe weather.
Rainfall totals from early Sunday through Monday evening are
expected to be generally in the 2 to 4 inch range. However,
isolated amounts up to 6 inches will be possible. While the
distribution of these totals remains uncertain, the best chances
for the higher rainfall amounts appears to be along and south of
the I-10 corridor. This may lead to some localized flooding for
portions of the area. Please see the hydrology discussion below
for information about potental impacts on area rivers.
Temperatures will vary quite a bit on Sunday, with upper 60s for
highs in the west as the onset of the rain will be earlier in the
day. To the east, expect temperatures to reach the lower to mid
70s before the squall line moves through. The cooler airmass will
spread over the remainder of the area for Monday, with highs
holding in the 60s area wide.
.Long Term [Tuesday Through Saturday]...
An upper level shortwavetrough amplifying the pattern and
enhancing local convection will lift northeastward Tuesday,
finally clearing precip from our area. Shortwave impulses will
continue to propagate through the upper level pattern through the
long term period, but will stay too far north of us to enhance
rainfall in the southeast again until the weekend. Temperatures
will be near normal, with highs in the upper 60s to mid 70s and
lows in the mid to upper 40s.
Friday night, the models diverge a bit with the GFS showing an
amplified trough over the central and northern plains, enhancing
surface cyclogenesis, with a cold front passage across the Ern
CONUS on Saturday. The Euro on the other hand, shows two far less
amplified Nrn and Srn stream troughs, with weaker cyclogenesis
over the Great Lakes from the Nrn trough and weakly enhanced
divergence over the Nrn GoMex from the Srn trough. Both patterns
mean increased rain chances for the weekend, but vary in which
areas are more likely to get rain. A model blend of the two
solutions has the highest chances (about 30%) for our western
[Through 18Z Sunday] VFR conditions are anticipated for the
remainder of the afternoon, except KDHN which may periodically
dip into the high-end MVFR ceilings in showers before returning to
VFR this evening. It will be well after midnight before MVFR
ceilings spread from southwest to northeast across KECP and KDHN,
and then well after dawn before any restrictions spread east to
KTLH and KABY. Showers and thunderstorms will likely hold off
until after 12z for most sites, the exception being KDHN. Gusty
conditions are expected tomorrow, especially at KTLH and KVLD
where gust could reach as high as 30 knots.
Winds and seas will be on the increase by late tonight as a storm
system approaches fromt he west. Small Craft Advisory conditions
are likely on Sunday, along with widespread showers and
thunderstorms. Conditions will improve on Monday before winds
increase back to moderate levels Monday night behind a cold front.
Winds and seas are expected to decrease and remain below headline
levels from Tuesday through the middle of the week.
Hazardous fire weather conditions are not expected over the next
As a low develops over the Srn Plains today and moves slowly
eastward, we`re in store for a rainy Sunday through Monday night,
with stronger thunderstorms possible on Sunday. Widespread
rainfall accumulations with this system are expected to be around
1.5-2.5 inches. Local hi-res guidance suggests that locally
higher amounts of 4 to 6 inches will be possible with stronger
storms, particularly in SE Alabama and the Florida Panhandle.
The widespread rainfall datavalues of 1.5-2.5 inches anticipated
are forecast to bring a few area rivers to action/bankfull stage
by mid week- the Withlacoochee River at Pinetta, the St. Marks
River at Newport, the Apalachicola River at Blountstown, and
several points along the Ochlockonee River. Ensemble guidance
suggests a 30% chance that the St. Marks River at Newport and the
Kinchafoonee Creek at Dawson may rise to minor flood stage by mid-
next week. In addition, with local rainfall totals of 4 to 6 inches
possible with stronger storms, additional rises of area rivers may
For the latest hydrology information, please visit:
.Preliminary Point Temps/PoPs...
Tallahassee 53 72 62 69 49 / 10 80 90 80 40
Panama City 60 70 61 66 49 / 10 90 90 70 30
Dothan 55 70 59 65 45 / 40 90 80 60 30
Albany 55 71 60 66 46 / 10 90 80 70 40
Valdosta 53 75 62 69 50 / 10 70 90 80 50
Cross City 50 75 66 71 56 / 10 50 80 80 60
Apalachicola 60 69 63 68 52 / 10 80 90 70 30