Area Forecast Discussion
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573
FXUS62 KTAE 271923
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
323 PM EDT Sat Sep 27 2014

.Near Term [Through Tonight]...

The 1 pm EDT regional surface analysis showed a developing,
quasi-stationary front off the SC coast, through central FL, to the
central Gulf of Mexico, and a high pressure ridge along the
Piedmont. Vapor imagery and upper air data showed a dramatic
increase in deep layer moisture along the Gulf Coast compared to 24
hours ago, as southwest flow in the mid to upper troposphere
advected ample tropical moisture. Numerous showers & thunderstorms
were developing along the front in the Gulf, in an airmass with
precip water values 1.5 times climatology. So far, with limited Q-G
forcing and instability (mainly due to cloud cover), there hasn`t
been much rain in our forecast area. However, we expect this to
change overnight as moisture and large scale lift gradually
increase. For the remainder of this afternoon & evening, the highest
PoP (50%) is around Cross City. Late tonight this shifts westward to
the FL Panhandle coast. There was still some dry boundary layer air
inland, which will help limit the PoP/QPF inland overnight. Lows
will be in the upper 60s (north) to lower 70s (south).

.Short Term [Sunday Through Monday Night]...

Deep layer moisture will continue to be pulled northward across
the Tri-state area as the upper trough approaches. Additionally,
models are consistent in showing the development of a surface low
along the central Gulf coast Sunday and lifting to the east-
northeast over our FA Sunday night through Monday. This feature
will further enhance convection along with the threat for locally
heavy rainfall, especially across our SE AL and Florida zones. QPF
amounts through the short term period are in the 1-3" range with
isolated amounts up to 6" possible. For this reason, we have
decided to issue a Flash flood Watch effective at 06z for all of our
Florida and SE AL zones. Temperatures will be at or above climo.

.Long Term [Tuesday Through Saturday]...

The 12z GFS and 00z EURO are in fairly good agreement on the timing
of the exiting upper trough and surface low Monday night through
Tuesday. However, the GFS is quicker to dry us with deep northwest
flow. Will keep a slight PoP in our easternmost zones on Wednesday
to account for this. Otherwise, deep moisture begins to return to
the region as early Thursday ahead of the next upper trough and
associated cold front. The front is forecast to push into our CWA on
Saturday. Expect temperatures to run near normal.

&&

.Aviation...

[through 18Z Sunday] MVFR cigs across our entire forecast area were
gradually lifting, and should reach VFR levels mid to late
afternoon. However, as has been the case the past several days, low
clouds will develop from east to west overnight, between 6Z (KVLD,
KTLH, & KABY) and 9z (KDHN & KECP). Occasional IFR cigs are
possible, especially at KVLD. The PoP is too low to mention rain at
any of the terminals today, but we expect period of rain at KECP &
KDHN on Sunday- with occasional TSRA. Elsewhere SHRA/TSRA will be
more isolated.

&&

.Marine...

Light to moderate Easterly flow will gradually shift to become
southerly by Monday ahead of a weak area of low pressure. Winds
may briefly reach exercise caution levels tonight but will but
now will keep under headline criteria. Winds are expected to be in
the 10 to 15 knots range for Sunday and Monday, but rather stormy
conditions are also likely during that time with locally higher
winds and seas near thunderstorms. A decrease in winds and seas is
expected for next week.

&&

.Fire Weather...

With plenty of deep tropical moisture headed our way during the next
couple of days, Wet Flag conditions will be in effect.

&&

.Hydrology...

General rainfall amounts of 1 to 3 inches are likely across the
forecast area through Monday, except 3 to 4 inches with locally
higher amounts around 6 inches possible in a short period of time
along the panhandle coast. These amounts are not expected to
result in any river flooding due to low flows from the recent dry
summer, although rises are certainly expected. However, isolated
instances of flash flooding cannot yet be ruled out for Sunday
into Monday, mainly along the panhandle coast and in the typically
vulnerable urban and low-lying areas. If confidence continues to
increase in this scenario, then a flash flood watch could be
issued as early as this afternoon for Sunday.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   72  84  71  87  72 /  40  80  70  70  20
Panama City   73  83  74  86  70 /  50  90  70  60  20
Dothan        68  83  69  84  66 /  30  90  70  60  20
Albany        68  84  69  86  68 /  20  80  70  80  30
Valdosta      70  85  70  86  70 /  30  60  60  70  30
Cross City    72  86  70  86  70 /  50  60  60  70  30
Apalachicola  74  83  75  86  72 /  60  90  70  60  20

&&

.TAE Watches/Warnings/Advisories...

FL...Flash Flood Watch from 2 AM EDT /1 AM CDT/ Sunday through Sunday
     evening for Calhoun-Central Walton-Coastal Bay-Coastal
     Dixie-Coastal Franklin-Coastal Gulf-Coastal Jefferson-
     Coastal Taylor-Coastal Wakulla-Gadsden-Holmes-Inland Bay-
     Inland Dixie-Inland Franklin-Inland Gulf-Inland Jefferson-
     Inland Taylor-Inland Wakulla-Inland Walton-Jackson-
     Lafayette-Leon-Liberty-Madison-South Walton-Washington.

GA...None.
AL...Flash Flood Watch from 1 AM CDT Sunday through Sunday evening
     for Coffee-Dale-Geneva-Henry-Houston.

GM...None.

&&

$$

NEAR TERM...FOURNIER
SHORT TERM...BARRY
LONG TERM...BARRY
AVIATION...FOURNIER
MARINE...BARRY
FIRE WEATHER...GOULD
HYDROLOGY...DVD




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