Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 211039
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
638 AM EDT Mon Jul 21 2014
.Near Term [Through Today]...
Updated at 638 AM EDT- The 11 pm EDT regional surface analysis was
complex, as a wavy, quasi-stationary front over the Southeast was
rather ill-defined. It extended from a broad, weak low pressure
system (1014 mb) in Southern MS, east-northeastward across Central
AL and GA. There was also a subtle trough along the FL Panhandle
Coast. Vapor imagery and upper air data showed ample moisture over
our region, though not the kind of deep layer moisture (and tropical
connection) that often results in widespread heavy rain for our
region this time of year. A fairly potent, positive-tilted trough
was translating southeastward over the Southeast, and extended from
Central TN to the TX coast.
A fairly large, poorly-organized MCS has developed along the FL
Panhandle coast and adjacent coastal waters, and was moving east at
10 to 15 MPH. This MCS appeared to be weakening somewhat, but even
if it does, more convection is likely to develop later this morning
and afternoon. Our forecast follows our 5 am EDT ensemble of
Convection Allowing Models (ECAM) closely, with PoPs ranging from 40
to 80% today. The highest PoP is along the FL Panhandle and North FL
coasts. The large scale environment (with weak winds aloft and
somewhat marginal lapse rates) doesn`t appear conducive for severe
.Short Term [Tonight Through Wednesday]...
The early part of the week will feature an upper level low just
west of our forecast area slowly retrograding westward to near New
Orleans by Wednesday. The stalled surface front across the area
will slowly lose its definition and mid-upper level ridging will
temporarily build back in with slowly rising heights. Therefore
the general trend should be slightly higher temperatures and lower
PoPs on Wednesday as compared to Tuesday.
For Tuesday, PWATs will remain around 1.9 inches (near normal)
over the eastern half of the area, and enough forcing for ascent
should exist to contribute to numerous showers and storms again
in those areas. Slightly drier air in the western half of the area
with PWATs closer to 1.7 inches (25th percentile) will likely lead
to lower convective coverage. Therefore, we included likely PoPs
(>55%) across the east with lower values west.
.Long Term [Wednesday Night Through Monday]...
The mid/upper level trough will persist across the local region
through the extended period. The trough will be wedged between
the Bermuda Ridge and strong ridging centered over the Desert
Southwest. Temperatures along with rain chances are expected to be
at or above climo each day.
[Through 18Z Tuesday] SHRA/TSRA were already developing across the
FL Panhandle. We expect TSRA/RA at KECP until late morning, at KTLH
and KDHN late morning through early afternoon, and KVLD and KABY
this afternoon. The rain will coincide with brief periods of low
VIS/CIGS and gusty winds. Outside of the rain, VFR conditions will
prevail. A return to just isolated TSRA and generally VFR conditions
are expected this evening and overnight.
Slightly higher winds (10-15 knots) lingering into today should
keep seas elevated around 2-3 feet, and significant wave heights
in that range are still being observed at the offshore buoys.
While this won`t rise to SCEC levels, it should still create
choppy conditions for mariners. Given the possibility for
lingering breezy winds and the active rip currents yesterday, our
general outlook for today is for a continued high risk of rip
currents in Walton, Bay, and Gulf counties as active rip channels
from yesterday may continue to be activated. Overall, though, the
trend in the forecast is for winds to gradually diminish along
with wave heights.
Rain chances will be quite high this week, especially in FL today.
Red Flag conditions are not expected this week.
With such deep layer moisture, heavy rain rates are expected today.
However, flash flood guidance is still quite high across most of our
region, and we expect convective cells to propagate quickly enough
to avoid excessive accumulations on a wide scale. The exception
would be if these high rates were to occur for a significant amount
of time over urban areas. The probability of this happening is not
high enough for a Flash Flood Watch, and we will just have to
monitor this as the day goes on. The Shoal River at Mossy Head is
above bankfull stage and will continue to be monitored. All other
rivers are also currently below flood stage.
.Preliminary Point Temps/PoPs...
Tallahassee 87 71 92 72 93 / 50 30 60 30 50
Panama City 86 75 89 75 89 / 80 20 50 20 40
Dothan 87 72 91 72 93 / 40 20 50 30 40
Albany 88 71 92 72 93 / 40 40 60 40 40
Valdosta 87 70 91 71 95 / 60 50 60 50 50
Cross City 87 71 92 72 93 / 70 50 60 40 40
Apalachicola 86 74 88 74 89 / 70 30 50 20 40
FL...High Rip Current Risk until 8 PM EDT /7 PM CDT/ early this
evening for Coastal Bay-Coastal Gulf-South Walton.