Severe Thunderstorm Warning 268, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1038 AM EDT TUE JUL 14 2015

.Near Term [Through Today]...

Previous forecast is on track. A similar pattern to yesterday
continues today. Large upper ridge remains centered over the
Southern Plains, with a broad (but amplifying) trough across the
northeastern quadrant of the country. At the surface, low pressure
is centered over the Great Lakes region with a broadening pressure
pattern through the Southeast. A 06z subjective analysis depicted
a stationary boundary from the Tennessee Valley, through northeast
Georgia, and off the Mid- Atlantic coast. Running from
Apalachicola, northeast along the western Atlantic coast sits a
trough.

Through today the +PV anomaly over the Great Lakes will dive into
the Mid-Atlantic. This will turn low layer flow more westerly
over the Appalachians. Subsequently, weak lee troughing is
expected to develop and build southeast into the Tri-State region.
In addition, W/SW steering flow will favor a wetter type 4/5
seabreeze regime this afternoon.

Some scattered showers are already developing along the tail of
the aforementioned trough near Apalachicola, expect these storms
to become more numerous through the morning. These storms will
likely disturb the climatological seabreeze pattern early this
afternoon. In general, storms are expected to fill in across the
Panhandle this morning and merge with what develops along the
seabreeze and the lee trough extending into southeast Alabama and
south Georgia. This convection will likely blend together and move
east across north Florida and south Georgia through the afternoon.

A warm, juicy, and unstable airmass is in place across the region
this morning and will only gradually mix through the afternoon.
Thus the high instability alone will be enough to force a few
strong to severe storms through the day today. The threat with any
strong storms will be damaging winds.

Although we'll be a little cooler than yesterday, the high
dewpoints will be able to force heat indices into advisory
levels this afternoon. Since convection is expected earlier near
the coast, it will likely keep temperatures too cool for an
advisory south of I-10 in north Florida.

&&

.Prev Discussion [659 AM EDT]...

.Short Term [Tonight Through Thursday]...

The position of a mid-upper level anticyclone will remain nearly
stationary on Wednesday and Thursday over the Arklatex region,
which will place our forecast area in N-NW flow aloft. Meanwhile,
low-level flow will be out of the west with abundant and deep
boundary layer moisture. Precipitable water values should be
around or above 2 inches during this forecast period; that would
suggest fairly high convective coverage each day, as would the
stronger westerly flow which usually contributes to more numerous
storms during the afternoon hours.

However, PoPs were also kept elevated at night - both for tonight
and Wednesday Night - due to the possibility of convection
initiating north of our forecast area and then pushing south given
the prevailing flow aloft. We can occasionally see organized
convective lines reach the Gulf coast in the summer months in
these sort of synoptic patterns, and several convection allowing
models show a version of that scenario. However, the timing and
intensity of such convective lines varies from model to model.
Given the possibility of organized lines of storms, damaging winds
will be a threat with any stronger storms or line segments during
the short term period. Southwest Georgia is outlined in a Slight
Risk of severe storms by the SPC for Wednesday. Organized and
severe storms may be more likely on Wednesday, but at least
isolated severe weather will be possible through the entire period
across the forecast area.

Heat indices on Tuesday and Wednesday could approach Heat Advisory
criteria (109 degrees) in some areas. However, this could be
significantly affected by convective timing and coverage, so
confidence is low in any particular scenario at this time.

.Long Term [Thursday Night Through Tuesday]...

Although our forecast area will remain on the eastern periphery of
the mid-upper level anticyclone, the ridge will build during the
extended forecast period with slight rises in heights aloft. This
will likely lead to slightly warmer temperatures and more widely
scattered showers and storms (with a more typical diurnal trend).

.Aviation...
[Through 12Z Wednesday]...

IFR/LIFR conditions have developed at TLH and ECP, but should
dissipate within the next hour or two. Thereafter, VFR will
prevail outside of thunderstorms. ECP, TLH, and VLD have the best
chance of storms, spreading from west to east through the day.

.Marine...

Westerly winds will persist through much of the rest of the week,
and will begin to increase later tonight. SCEC level winds (15-20
knots) appear likely from Wednesday into Thursday.

.Fire Weather...

Hazardous fire weather conditions are not expected over the next
several days.

.Hydrology...

Area rivers remain below bankfull levels. Scattered showers and
storms are expected this week, but heavy rainfall should be
relatively localized. Flooding is not expected on any of the
larger area rivers.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   95  76  93  76  93 /  60  30  50  30  60
Panama City   91  80  89  80  88 /  60  30  40  40  50
Dothan        96  77  95  76  94 /  30  20  40  30  40
Albany        96  76  95  74  93 /  30  40  50  40  40
Valdosta      97  75  93  74  93 /  60  40  50  30  60
Cross City    93  76  90  76  92 /  40  40  50  40  60
Apalachicola  91  80  90  80  92 /  50  30  40  40  60

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...HEAT ADVISORY until 7 PM EDT /6 PM CDT/ this evening FOR Gadsden-
     Jackson-Leon.

GA...HEAT ADVISORY until 7 PM EDT this evening FOR Baker-Ben Hill-
     Berrien-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-Early-
     Grady-Irwin-Lee-Miller-Mitchell-Quitman-Randolph-Seminole-
     Terrell-Thomas-Tift-Turner-Worth.

AL...HEAT ADVISORY until 6 PM CDT this evening FOR Coffee-Dale-Geneva-
     Henry-Houston.

GM...NONE.
&&

NEAR TERM...WESTON/HARRIGAN
SHORT TERM...LAMERS
LONG TERM...LAMERS
AVIATION...HARRIGAN
MARINE...LAMERS
FIRE WEATHER...HARRIGAN
HYDROLOGY...MCDERMOTT