Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 020738
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
338 AM EDT SUN AUG 2 2015
.Near Term [Through Today]...
A weak surface low has developed early this morning in Apalachee
Bay, embedded in a larger northeast to southwest oriented surface
trough. Strong low/mid level southwesterly flow south of this trough
will continue to push tropical moisture into the southeastern Big
Bend counties today. Once again, the focus of the heaviest rain will
be in Taylor and Dixie Counties as the weak surface low tracks
northeast and keeps the onshore flow in place to its south. With
radar estimated storm total amounts close to 15 inches along the
coast in these counties, any additional rainfall will continue to
worsen the ongoing flooding situation. With the highly efficient
warm rain processes forecast to continue in the area today, another
4 to 6 inches of rain is not out of the question through tonight.
Farther north, the offshore flow to the north of the surface low and
associated trough will provide a sharp cut-off to the heavy rain.
Only scattered storms are expected this afternoon along the I-10
corridor, with even less coverage further north where a drier
airmass will be in place. Will trim back the Flash Flood Watch
further this morning to remove Madison and Jefferson Counties.
Away from the widespread rain in the southeastern Big Bend, hot
temperatures are expected under sunnier skies. Expect to see highs
in the mid 90s from southwest Georgia into the Florida Panhandle and
.Short Term [Tonight Through Tuesday]...
After a few days of very wet conditions across the southeastern
third of the forecast area, the pattern will finally begin to
shift as a weak surface low over the Eastern Gulf moves away from
the region, taking much of the moisture with it. Still some
potential for locally heavy rainfall overnight, though the overall
forcing looks to diminish significantly after 06z Monday. Drier
air will move into the northwestern portion of the forecast area
on Monday, keeping rain chances confined to the daily sea breeze
circulation at the coast. Much the same is expected for Tuesday as
the subtropical ridge moves back over the Florida Peninsula.
High temperatures throughout the short term period will generally
be in the low to mid 90s, with the warmest values further to the
northwest near to Albany and Dothan, where less afternoon convection
.Long Term [Tuesday Night Through Sunday]...
The first half of the long term period will feature a typical
summertime pattern with our region starting on the western
periphery of the subtropical ridge on Wednesday and the ridge
building into the eastern Gulf of Mexico by Thursday. This pattern
typically keeps 30 to 40 percent rain chances in the forecast,
primarily in North Florida nearer the sea breeze boundaries.
Friday will transition back to a wetter period as a frontal system
moves through the Tennessee River Valley and into the Southeast.
Long range guidance for Saturday and Sunday suggest a frontal
boundary may once again stall across the region, with rain chances
increasing above climatology by the end of the period.
Temperatures will remain near normal throughout the period with
highs mainly in the low to mid 90s through Thursday. Thereafter,
temperatures will be a little cooler as more afternoon storms are
[Through 06Z Monday]IFR cigs will likely impact KTLH, KABY, and
KVLD this morning, with cigs rising to VFR levels by mid to late
morning. Lower chances of afternoon/evening storms today, with
greatest threat at KVLD.
Southwesterly flow at advisory levels will continue today around
the eastern edge of a weak low pressure area in Apalachee Bay.
As this feature moves away from the marine area on Monday, expect
winds and seas to return to normal summertime levels by Tuesday.
No fire weather concerns through the next several days.
Rainfall totals since Friday morning across Southeastern Taylor
and Dixie Counties were in the 10 to 15 inch range as estimated
by radar with a couple of higher totals near 18 to 19 inches. A
couple of observations in excess of 10 inches were also reported
in Dixie County in the last 24 hours. Widespread areal flooding
is common across these areas, as natural drainage systems are
overcome by excess runoff. Unfortunately, little if any
improvement in the flood situation is expected today. With the
weak surface low still west of the Big Bend, expect another round
of heavy rainfall, though not as extreme as Saturday. Another 3 to
6 inches with isolated heavier totals is expected.
The primary focus for river flooding is on the Steinhatchee River
where modest rises continue. With basin areal totals in the 9 to
12 inch range in the last 48 hours, there are some strong
similarities with this event and the 5/17/14 flood event.
Accounting for basin areal average rainfall today of 2 to 3
inches, the river is anticipated to crest on Monday afternoon near
15.2 feet. This is just below moderate flood stage (15.7 feet).
Should rainfall amounts today be on the higher side, this forecast
would need to be revised upward.
Elsewhere, river flooding is not anticipated. The bulk of the
heavy rainfall in the Suwannee Basin fell south of Rock Bluff.
Though some minor rises have occurred at Wilcox and Manatee
Springs, this portion of the river will remain safely below action
stage. With the increased runoff from further upstream and tides
running about a foot above normal at the Suwannee River Entrance,
the Fowlers Bluff point will likely reach action stage at each high
tide cycle through Monday afternoon.
.Preliminary Point Temps/PoPs...
Tallahassee 94 76 95 76 95 / 40 20 40 20 40
Panama City 90 77 91 78 88 / 30 20 30 20 30
Dothan 95 73 96 74 95 / 20 10 10 10 20
Albany 94 74 96 74 96 / 20 10 10 10 20
Valdosta 90 75 96 75 95 / 40 20 30 20 30
Cross City 85 76 91 76 92 / 80 80 60 30 40
Apalachicola 90 80 91 78 87 / 40 50 30 30 20
FL...FLASH FLOOD WATCH through this evening FOR Coastal Dixie-Coastal
Taylor-Inland Dixie-Inland Taylor-Lafayette.
GM...SMALL CRAFT ADVISORY until 5 AM EDT Monday FOR Coastal waters
from Suwannee River to Keaton Beach out 20 NM-Waters from
Suwannee River to Apalachicola FL from 20 to 60 NM.