Damaging Winds in Alabama, August 7, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
934 AM EDT FRI AUG 7 2015

.Near Term [Through Today]...

A shortwave trough sits over the Southeast this morning, with its
associated +PV anomaly seen clearly on WV imagery this morning. At
the surface, a frontal boundary runs from the Mid-Atlantic through
the northern tier of GA/AL/MS, and up into the Mississippi valley.
Also, a weak surface trough extends south through SC into
southeast GA. Convection this morning has remained mostly offshore
due to the lack of forcing across land areas.

Two areas of convection are expected across the Tri-State region
today. The first will be late morning and early afternoon along
outflow left from last night's MCS, and will primarily affect the
southeastern third of the region. The next wave of storms will be
later in the afternoon when the aforementioned front dips far
enough south to force showers and thunderstorms across the entire
region (coupling with what's left of the MCS over Arkansas this
morning). For the second round of storms, SBCAPE around 3000
J/kg, deep layer shear greater than 30 knots, and mid-level lapse
rates around 6 deg C all favor a higher than typical summertime
threat for severe weather. While damaging winds will be the
primary threat, marginal low-layer shear yields a non-zero threat
for an isolated tornado as well. These threats are well agreed
upon by our local hi-res modelling suite and a local severe
weather diagnostic tool. Additionally, the Storm Prediction Center
has expanded its Slight Risk to all but the northeastern half of
our south Georgia counties.

&&

.Prev Discussion [407 AM EDT]...

.Short Term [Tonight Through Sunday]...
As the Eastern CONUS trough moves offshore and into the Western
Atlantic, pushing the weak frontal boundary south of the forecast
area, some drier air will move into the region. While the models
differ on how much drying will take place, there seems to be
reasonable consensus that rain chances for the northern half of
the region will be below climatology during the short term period.
Nearer to the coast, afternoon convection will be aided by the sea
breeze circulation, so scattered coverage in these areas for
Saturday and Sunday afternoon seems like a good bet.

The main story through the short term will likely be the warm
temperatures. Model guidance this cycle is indicating the
potential for some low 100 degree readings by Sunday as the mid
level ridge over Texas extends eastward across the Gulf of Mexico.
Have trended the forecast upward this cycle, but not quite as warm
as the GFS-based MAV guidance. Even though it will be warmer than
normal on these days, the presence of some drier air will help
keep heat indices just below advisory criteria in the afternoon.

.Long Term [Sunday Night Through Friday]...
An atypical pattern for August is expected to evolve over the long
term period. Ridging across the Gulf of Mexico will break down on
Tuesday as a large amplitude trough drops out of the Great Lakes
and toward the Eastern Seaboard. A frontal boundary will approach
the region on Tuesday and slowly move through the region on
Wednesday. It's expected that Tuesday/Wednesday will be relatively
high PoP days across the region. The 07/00z GFS, along with the
07/00z Euro show the frontal boundary clearing much of the
forecast area by Thursday (rather unusual for early August) as the
a large mid level trough moves into the Western Atlantic. By the
end of the period, the region will be between a weakness in the
Mid-CONUS ridge and the subtropical ridge, suggesting at least
some thunderstorm chances, though increasing mid level dry air,
should keep the greatest chance for storms confined to the
coastal zone.

Temperatures throughout the long term period will generally be at
or just below normal, with highs in the lower 90s, after Tuesday.

.Aviation...
[Through 06Z Saturday] A stormy day is expected with scattered to
numerous showers and thunderstorms developing by mid-morning and
continuing through the day. A few storms are expected to be severe
with strong wind gusts.

.Marine...
Winds will increase to cautionary levels today ahead of a frontal
boundary. By Saturday afternoon, winds will weaken as the boundary
dissipates south of the waters. Expect typical light winds and
low seas thereafter through Tuesday.

.Fire Weather...
Red flag conditions will not occur over the next several days.

.Hydrology...
Fairly widespread coverage of showers and storms is expected
across the region today. Average rainfall amounts of 1 to 2
inches is anticipated, with locally higher amounts in excess of 4
inches possible, especially across western portions of the
region. This may result in minor flooding in some areas.

After today, a stretch of relatively drier conditions is expected
through Tuesday.

The Steinhatchee River remains in minor flood stage but is
dropping more quickly this morning, and should be below flood
stage late tonight. With the heaviest rainfall today expected over
the western portions of our region, no additional river flooding
is anticipated at this time.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   93  76  97  75  98 /  60  40  30  10  30
Panama City   89  79  92  76  92 /  50  40  30  10  30
Dothan        92  75  97  75  99 /  60  30  30  10  20
Albany        94  73  97  74  98 /  60  20  20  10  10
Valdosta      92  74  97  74  99 /  60  30  20  10  30
Cross City    90  77  94  74  95 /  50  40  40  10  40
Apalachicola  89  79  90  77  91 /  50  40  20  10  30

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...HIGH RIP CURRENT RISK through late tonight FOR Coastal Bay-
     Coastal Franklin-Coastal Gulf-South Walton.

GA...NONE.
AL...NONE.
GM...NONE.
&&

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