Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 010742
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
342 AM EDT SAT AUG 1 2015
.Near Term [Through Today]...
A northeast to southwest oriented low/mid level trough currently
bisects the local forecast area, and will remain generally
stationary through the day. South of the trough axis, low-level
southwesterly flow will increase with 850mb winds approaching 30
knots moving into the southeastern Big Bend this afternoon. This
area will likely be the focus of the heaviest rainfall today. Expect
area average rainfall totals of 2 to 3 inches across Taylor,
Lafayette, and Dixie counties. Locally higher amounts of up to 6
inches are not out of the question.
How far north the heaviest rain spreads is a bit more in question.
Tallahassee and the I-10 corridor will reside closer to the low/mid-
level trough axis, and have less forcing for heavy rain, despite
plentifuly deep moisture and an unstable airmass. Expect good
coverage of rainfall in this region (and furthern north). However,
the heaviest rainfall is expected to be more localized with area
average rain totals of around 1 inch through the afternoon.
Localized amounts could be 2 to 4 inches and, with high rain rates,
pose the risk for some flash flooding. Thus will leave the northern
extent of the Flash Flood Watch intact for now.
.Short Term [Tonight Through Monday]...
A frontal zone stalled across the region will continue to be a
focus for shower and thunderstorm development through at least
Sunday. The airmass south of this boundary is quite moist, with
precipitable water values in excess of 2 inches. Hi-res guidance
continues to indicate the potential for very heavy rainfall
tonight into Sunday across the Florida Big Bend, particularly to
the east of the Aucilla River. The mean of the ECAM guidance is
above 5 inches from tonight through Sunday morning, with
individual members suggesting significantly heavier totals are
possible. Will continue the flash flood watch through tonight, and
then evaluate in future forecasts whether an extension into the
daytime hours on Sunday is needed based on Saturday`s rainfall
Drier air on the north side of the boundary will make a little
further progress southward by Monday, resulting in a fairly tight
PoP gradient across the region at the end of the short term
period. Moreover, the boundary becomes less defined by Monday, so
expect rain chances, even in the Florida Big Bend to be a little
lower than over the weekend.
Convection on Sunday will keep temperatures generally in the upper
80s to lower 90s in the Florida Big Bend, but with more isolated
coverage across Srn AL and SW GA, expect highs in the mid to upper
90s. Temperatures in the mid to upper 90s are expected across the
entire region on Monday afternoon, with heat indices in the mid
.Long Term [Monday Night Through Saturday]...
The subtropical ridge will become more established across the
Florida Peninsula and Eastern Gulf by Tuesday, signalling a return
to a typical summertime pattern of scattered afternoon and evening
storms. By Thursday, model guidance has a storm system moving
through the Southern Appalachians. It`s expected that this system
will enhance afternoon/evening convection by the weekend across
the region, with rain chances moving back to near 50 percent. High
temperatures throughout the period will continue to be warm,
generally in the mid 90s inland and lower 90s at the coast.
[Through 06Z Sunday] IFR cigs are possible at KVLD and KABY this
morning. VFR conditions after 12Z will give way to showers and
thunderstorms by early afternoon. Best chances for TSRA are KECP,
KTLH, and KVLD. However, all terminals are likely to be impacted at
some point during the afternoon.
As a low pressure system in the Gulf lifts northeastward across
north Florida and southern Georgia this weekend, the gradient will
tighten and increase winds and seas to advisory levels. After the
system exits early next week, winds and seas will quickly return
to normal levels.
There are no fire weather concerns through early next week.
Rainfall amounts on Friday were locally heavy across the
Southeastern Florida Big Bend and across portions of Southwestern
Georgia. With the very moist airmass still in place across far
Southern Georgia and into the Florida Big Bend, a flash flood
watch remains in effect through Saturday night. Model guidance
indicates the heaviest rain amounts will be across the
Southeastern Florida Big Bend, where 3 to 4 inches of rain should
be common over the next couple of days.
With the bulk of the heavy rainfall expected to fall across the
Southern portion of the area, and the lower part of the river
basins, the potential for river flooding in the days ahead is low.
Only the Steinhatchee River is anticipated to reach flood stage at
this time based on the latest QPF forecasts.
With the flash flood watch in effect, the primary concern will be
flooding in slow drainage areas, as rainfall rates should easily
exceed 3-4 in/hr with many of the storms on Saturday/Saturday
.Preliminary Point Temps/PoPs...
Tallahassee 90 76 92 75 95 / 70 60 50 40 30
Panama City 88 76 90 75 90 / 60 50 40 30 30
Dothan 91 73 95 73 96 / 60 40 30 10 20
Albany 91 74 95 74 96 / 70 40 30 10 20
Valdosta 88 75 92 74 94 / 70 60 50 40 30
Cross City 85 76 86 75 88 / 80 80 80 50 50
Apalachicola 87 77 87 77 88 / 70 60 60 40 40
FL...FLASH FLOOD WATCH from 8 AM EDT /7 AM CDT/ this morning through
Sunday morning FOR Calhoun-Coastal Bay-Coastal Dixie-
Coastal Franklin-Coastal Gulf-Coastal Jefferson-Coastal
Taylor-Coastal Wakulla-Gadsden-Inland Bay-Inland Dixie-
Inland Franklin-Inland Gulf-Inland Jefferson-Inland Taylor-
GA...FLASH FLOOD WATCH from 8 AM EDT this morning through Sunday
morning FOR Berrien-Brooks-Colquitt-Cook-Decatur-Grady-
GM...SMALL CRAFT ADVISORY THROUGH 8 PM EDT SUNDAY FOR
Keaton Beach to the Suwannee River out to 20 nautical miles
Suwannee River to Apalachicola from 20 to 60 nautical miles