Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 130641
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
241 AM EDT Mon Oct 13 2014
.Near Term [Through Today]...
A strong short wave moving across the TX/OK panhandles early this
morning will amplify the upper level trough and close off a low over
SW Oklahoma by daybreak. This feature will deepen as it moves
east-northeastward toward the Missouri Valley this evening. By 00z
Tuesday, the associated surface low is forecast to be near the MO/AR
border with the southward extending cold front through western
Louisiana. Deep layer moisture will be increasing ahead of this
system in the moderate to strong southerly flow. By afternoon/early
evening we expect at least scattered showers and thunderstorms to
develop or advance into the western portions of our CWA with most of
the convection arriving after midnight. Although an isolated storm
or two may briefly be strong to severe today, the greatest severe
threat will occur during the short term period (see discussion
below). PoPs today will be tapered 60% far west to nil far east.
Temps will be held down a few degrees with the increased cloud cover
and prospects for rain but will still be above seasonal levels.
.Short Term [Tonight Through Wednesday]...
The upper low will lift northeast across Missouri tonight to a
position near St. Louis by 00Z Wednesday. The occluded system will
then move very slowly east over the following 24 hours. The
associated cold front will be approaching the Mississippi River by
00Z Tuesday and enter far western AL by 12Z. The front will
traverse our forecast area between 15Z Tuesday and 06Z Wednesday.
PoPs will be in the categorical range ahead of the front. Because
the system will be moving slowly, our concern for localized
flooding has increased a bit. See the hydrology section below for
The biggest concern with this system, however, remains the severe
weather threat. We continue to see decent 0-6km shear values in the
40-50kt range ahead of the front, but it is the 0-1km values that
cause the most concern as they are in the 25-35 kt range. Provided
sufficient destabilization is realized, isolated tornadoes would be
a possibility. The most prevalent threat though will be damaging
straight-line winds in bowing segments within the primary convective
line. The severe threat will begin during the overnight hours across
our western zones, shifting across the central and eastern zones
during the day on Tuesday. Again, the primary limiting factor in
this scenario will be the amount of instability that is present.
Abundant cloud cover could keep MLCAPE values in check under 1000
J/kg. However, it is possible we will see higher values which would
be more problematic. We plan to mention isolated severe in the grids
for now with later shifts possibly adding further enhancements if
confidence increases with respect to the degree of destabilization
with this system.
.Long Term [Wednesday Night Through Monday]...
With stacked high pressure moving over the southeast in the wake of
the cold front Tuesday night, a cooler, drier airmass will take over
the area. Highs will be in the upper 70s to around 80 until the
weekend, then warm to the low 80s Saturday and Sunday. Lows will be
in the low to mid 50s Wednesday and Thursday night, with mid to
upper 50s after that.
[Through 06Z Tuesday] Expect an IFR ceiling/visibility mixture at
ECP, DHN, and VLD. Elsewhere, an MVFR mixture is likely.
Restrictions will break by 15z except at DHN and ECP where low
ceilings will linger longer. Showers and thunderstorms in advance
of a strong cold front will begin to spread from southwest to
northeast possibly impacting DHN and ECP after 18z and all
remaining sites around or just after 00z.
Winds will increase ahead of an approaching cold front today through
Tuesday. Cautionary conditions are expected today, but winds could
reach marginal advisory criteria across the Panhandle waters this
afternoon. Advisory level winds will spread across the entire
forecast area tonight and remain elevated through much of Tuesday.
Winds will diminish as they shift to the west and then northwest
Tuesday night behind the front, and then remain below headline
criteria for the remainder of the work week.
High dispersion values are expected today as transport winds
increase ahead of an approaching low pressure system. Showers and
thunderstorms will be widespread tonight and Tuesday, drying out
once again by Wednesday behind a cold front. However, minimum
relative humidity levels are expected to stay above critical
thresholds and Red Flag conditions are not expected at least
through the remainder of the week.
The next frontal system will bring 2-3 inches of rain to our western
zones diminishing to around an inch across South Central GA and the
eastern FL Big Bend. Isolated totals up to 5 inches will be possible
over parts of Southeast AL and the FL Panhandle. Areas that see
these higher amounts could see some flooding, particularly in poor
drainage areas. Rivers are running quite low, so even these rainfall
amounts should not result in any main-stem river flooding. However,
some of the flashier streams and creeks in the western HSA could see
sharp rises beginning late tonight.
.Preliminary Point Temps/PoPs...
Tallahassee 88 74 82 58 80 / 20 70 80 50 10
Panama City 87 74 81 60 79 / 50 80 90 20 10
Dothan 87 70 80 53 78 / 40 80 90 20 10
Albany 90 71 80 57 78 / 20 50 80 50 10
Valdosta 89 69 82 61 79 / 10 30 80 60 20
Cross City 90 70 84 68 81 / 10 30 70 60 20
Apalachicola 85 75 82 62 79 / 40 80 90 40 10
FL...High Rip Current Risk through late tonight for Coastal Bay-South
GM...Small Craft Advisory from 2 AM to 8 PM EDT Tuesday 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.
Small Craft Advisory from Noon today to 11 PM EDT Tuesday for
Coastal waters from Apalachicola to Destin FL out 20 NM-
Waters from Apalachicola to Destin FL from 20 to 60 NM.