Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 131419
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1019 AM EDT Thu Jun 13 2013
.NEAR TERM [Through Tonight]...
The 12z KTAE sounding this morning reveals an unstable atmosphere
with MLCAPE values already exceeding 3000 j/kg and delta thetae
values around 39. Mid level lapse rates are also steeper than
normal around 7C/km, and some mid-level dry air is noted. These
values point to the potential for wet microbursts this afternoon
with any storms that are able to develop, so gusty wind wording
was added for this afternoon. However, storm coverage is not
expected to be particularly high this afternoon with northwest
flow aloft and upper level ridging still dominating the local
area. PoPs this afternoon still range from 20-40 percent, highest
across the eastern Florida panhandle and big bend. Although the
threat for a few stronger storms is there this afternoon, most
areas will not see anything.
The sea breeze is not expected to make a lot of inland penetration
today with the northwest flow, and temperatures will soar into
the mid to upper 90s across inland locations. With dewpoints
expected to remain in the upper 60s to lower 70s, heat indices
will be around 105 this afternoon.
By this evening into the first part of the overnight hours, an upper
level shortwave is expected to dive southeastward and approach the
area. This will likely induce MCS development to our north during
the late afternoon with a line of storms approaching our northern
zones. The main question will be how much intensity remains with the
storms as they move into our forecast area. The current timing
consensus from the hi-res guidance does not have any potential MCS
moving into the northern zones until well after sunset, which is a
limiting factor for storm intensity. Indeed, the hi-res guidance
has this line of storms weakening rapidly as it moves into our
area, although only a small error in the weakening trend could
bring strong to severe storms across our forecast area border, so
this still bears close watching.
.SHORT TERM [Friday Through Saturday Night]...
The short term period begins with an upper level pattern much like
the one our area has been under for the past couple of days. The
only difference being now an upper level trough is moving off the
eastern seaboard, and deep layer ridging is advancing eastward. A
weak surface cold front, associated with the upper level trough,
is expected to be just north of the Florida border by 12Z Friday.
Therefore, expect an enhanced PoP ahead of the cold front as it
slowly advances southward. The Storm Prediction Center has a 5%
probability of severe weather outlined for ahead of the surface
cold front. If severe weather should occur, it will likely be high
winds. Looking at the equivalent potential temperature difference
between the surface and the 500-700mb layer, values are in the
lower 30s, which would indicate a marginal potential for damaging
winds being transported to the surface. The mid-level temperatures
are too warm to support the possibility of severe hail making it
down the surface.
By early Saturday morning, the cold front should stall out south
of our CWA. Therefore expect drier conditions throughout the day
on Saturday with no POPs expected. PWATs throughout the area will
be less than 1.3, which is abnormally low for this time of year.
The surface high pressure will quickly push eastward through the
day on Saturday with winds transitioning from northerly to
easterly. By the end of the near term period winds will be
southerly, returning our area to our normal summertime weather
.LONG TERM [Sunday through Wednesday]...
After the potential system passes Thursday night, high pressure
aloft and at the surface will build eastward and be the main
synoptic scale influence on the forecast area`s weather through
Tuesday. On Tuesday, another shortwave will propagate through the
upper level ridge and set up a pattern similar to Thursday night
(see short term). Highest PoPs in the forecast period are Tuesday
and Wednesday. Expecting highs in the 90s and lows in the low 70s
through the long term period.
[Through 12z Friday] Isolated to scattered convection is expected
this afternoon with the greatest chances at KTLH and KVLD. A few
storms could be on the strong side with gusty winds. Late in the
evening, a line of storms could approach from the north and affect
KABY and KDHN, but timing and coverage are still uncertain with an
overall weakening trend anticipated as they move into the area.
With the approach of a surface cold front, the pressure gradient
will tighten allowing for increased winds. Beginning this
afternoon, small crafts should exercise caution with winds
expected to be 15-20 knots through early Friday morning. A chance
for thunderstorms is expected through the day on Friday.
Red Flag or near Red Flag conditions are not anticipated across the
Tri-State area for the next several days.
River gauges are expected to remain below flood stage for the next
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 97 73 94 71 93 / 30 20 30 10 10
Panama City 91 76 88 77 87 / 30 10 30 20 10
Dothan 98 72 94 70 95 / 20 40 20 0 10
Albany 97 72 93 70 93 / 20 40 10 0 10
Valdosta 99 71 95 70 95 / 40 30 30 10 10
Cross City 93 72 91 72 92 / 30 20 30 20 10
Apalachicola 89 77 87 76 86 / 20 10 30 20 10