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FXUS62 KTAE 181321
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
921 AM EDT Fri Apr 18 2014

...Heavy Rain and Flooding Concerns Continue into this Evening...

...Strong to Severe Storms Possible mainly SE Big Bend and adjacent
Waters...

.Near Term [Through Today]...

Mid morning analysis shows that the leading edge of mid/upper
trough continues to dig ESE across Cntrl Gulf region. Closed low
over LA. Low Strong jet extends from base of trough Newd to mid-
Atlc states while several shortwaves move across SE region. Lead
shortwave crossed early this morning leading to blowup of local
convection. Another potent shortwave across extreme E TX diving
down base of trough increasing divergence across Nrn Gulf of Mex
setting us up for next round. At surface...latest MSAS confirmed
by marine obs show that upper features have generated MCS low
south of Mobile and latest radar pix show it only meandering N/E
in last hour. Warm front extends Ewd across Cntrl FL. All this
providing excellent isentropic lift...and has strengthened MCS
yielding plume of moderate to heavy deep layer moisture moving
Newd towards CWA which will increase rainfall amount and
intensity.

Later today...TX shortwave will amplify SEWD helping to generate
closed H5 LOW. Guidance tracks MCS slowly Newd across Wrn FL
Panhandle early aftn then just south of Apalachicola during the late
aftn. Assocd warm front will likely reach I-10 by mid to late-aftn.
This would strengthen Sly flow...intensity moisture plume as it
overspreads CWA and further increase amount and intensity of rain as
low approaches. This would also place the axis of heaviest rain from
Wrn Panhandle thru SE AL and SW GA with the strongest forcing along
and just north of the warm front. General 1-2 inches 6 hr rainfall
totals (2 to 4 inch total) are expected but higher amounts are
likely along and just east of track...i.e. coastal counties from Bay
to Wakulla. The only possible curb would be a dry slot currently
seen on radar south of Panama City. But latest pix show little N/E
movement. With precip water values 50 to 100% above climo, rain
rates will occasionally be very high, so we will leave our Flood
Watch up and unchanged for our entire forecast area. The global
model consensus brings H5 low to FL Panhandle while surface low
moves Newd into NE FL by 06z Sat. So wrap around rain will
continue especially across NE third of CWA. Clouds and rain will
keep max temps well below normal for portions of CWA...near 60
north to mid 70s SE Big Bend.

As of 9 AM EDT...rainfall totals were already 2-3 inches across
Panhandle and 1-2 inches across the Big Bend...SE AL and SW/S/Cntrl
GA. This included Chipley 3.03...Mossy Head 2.80 and Alpine Heights
2.65 in Walton County...Parker (Bay) 2.53...Panama City 2.43...
Geneva AL 2.35...DeFuniak Springs 2.29...Tallahassee AP...1.70 and
Apalachicola 1.47 inches.

Although rain and flooding continues to be the main issue...the
threat of strong to isold severe storms is non-zero across mainly
Taylor and Dixie counties and adjacent waters. Although mid/upper
lapse rates are expected to remain weak...limiting destabilization...
Convection Allowing Model (CAM) forecast SBCAPE is in the 500-1000
J/kg range this afternoon in the warm sector with veered low level
winds around Cross City and Perry. Given the expected 0-1 km bulk
shear magnitude will be around 30 KT in that area, it`s reasonable
to be concerned about isolated, low-topped supercells- with
damaging wind gusts or perhaps even a brief tornado especially if
GFS with its more Nrn track (rather then ECMWF) ends up verifying.
Elsewhere we think that thunderstorms will be elevated enough to
limit vertical mixing, though the low level winds are strong
enough that wind gusts up to 40 MPH are possible.

Other concerns to be monitored include possible coastal flooding this
afternoon at high tide across coastal Big Bend, high surf advisories
and high rip current risk for Walton thru Franklin coasts and gale
force winds or gusts for the nearshore panhandle waters and all the
offshore waters.

&&

.Hydrology...

We continue to be on track for a moderate to heavy rainfall event
across the forecast area today and tonight. Rainfall totals of 2
to 4 inches are expected to be fairly common, with isolated higher
amounts perhaps up to 6 to 8 inches possible. In general, the
rivers most likely to flood and have higher impacts will be in the
Florida Panhandle and Big Bend where flows are already somewhat
elevated. Where the heaviest rain falls, there should also be
other flooding on smaller streams and creeks, as well as areas of
high water in low-lying areas and fields.

A more detailed hydrology discussion is available on our ESF
(Hydrologic Outlook) product, which can be found here:

http://www.srh.noaa.gov/product.php?site=NWS&product=ESF&issuedby=TAE

The most up-to-date river forecast information can always be found
on our AHPS page (below).

http:/water.weather.gov/ahps2/index.php?wfo=tae.

&&

.Prev Discussion [645 AM EDT]...

.Short Term [Tonight Through Sunday]...

The surface low pressure system will be departing to our east
tonight but rain chances will continue through Saturday as wrap
around moisture associated with the upper low swings through the
Tri-state region. Most of this rain should be light. Deep layer
ridging will begin to build in on Sunday with warming temperatures
and dry conditions.


.Long Term [Sunday Night Through Friday]...

By early next week the next weak trough and shortwave moves into
Gulf region with weak zonal flow across local area. A surface low
well to our NW brings a weak front to the Nrn Gulf before retreating
back Nwd on Wed. This will bring a slight chance of rain and isold
thunderstorms to the NRN counties Tues and Tues night followed by
drying trend.  Throughout the entire period, both high and low temps
will shows a gradual warming trend. Inland highs Monday in the upper
70s to around 80 will rise to the mid 80s Wed and Thurs. Inland Lows
Sun night in the low to mid 50s will rise by Thurs night to the low
60s.


.Aviation...

[Through 12z Saturday] Rain, occasional thunderstorms, and low
cigs (lower MVFR to IFR) are expected at all terminals today. The
heaviest rain will end from south to north this evening, followed
by IFR cigs and occasional DZ.


.Marine...

Winds and seas will continue to increase today with gale
conditions developing over the western and offshore legs. For the
nearshore waters of the Big Bend...advisory conditions will
prevail at least through the passage of the low pressure system
tonight. The gale conditions for the remainder of the coastal
waters will also subside tonight with advisory conditions
diminishing by Saturday evening. The strong onshore flow will
result in heavy surf and high risk of rip currents along area
beaches from Franklin County westward. A coastal flood watch is
also in effect along Wakulla County eastward to the mouth of the
Suwannee River.


.Fire Weather...

With such wet conditions today, there will be no fire weather issues
(i.e. Red flag conditions) through at least this weekend.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   69  53  67  51  76 / 100  60  30  10   0
Panama City   66  50  72  54  77 / 100  30  10   0   0
Dothan        63  48  70  51  76 / 100  50  20   0   0
Albany        63  50  65  50  75 / 100  80  40  10   0
Valdosta      69  55  65  51  75 / 100  80  40  10   0
Cross City    77  59  68  51  77 / 100  60  30  10   0
Apalachicola  70  56  71  53  73 / 100  30  10   0   0

&&

.TAE Watches/Warnings/Advisories...

FL...Flood Watch through late tonight 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.

     COASTAL Flood Watch until 8 PM EDT this evening for Coastal
     Dixie-Coastal Jefferson-Coastal Taylor-Coastal Wakulla.

     High Rip Current Risk until 8 PM EDT /7 PM CDT/ this evening for
     Coastal Bay-Coastal Franklin-Coastal Gulf-South Walton.

     High Surf Advisory until 2 AM EDT /1 AM CDT/ Saturday for
     Coastal Bay-Coastal Franklin-Coastal Gulf-South Walton.

GA...Flood Watch through late tonight for Baker-Ben Hill-Berrien-
     Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-Early-
     Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell-Quitman-
     Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth.

AL...Flood Watch through late tonight for Coffee-Dale-Geneva-Henry-
     Houston.

GM...Small Craft Advisory until 8 PM EDT this evening for Apalachee
     Bay-Coastal waters From Ochlockonee River to Apalachicola
     FL out to 20 NM-Coastal waters from Suwannee River to
     Keaton Beach FL out 20 NM.

     Gale Warning until 8 PM EDT this evening for Coastal waters from
     Apalachicola to Destin FL out 20 NM-Waters from Suwannee
     River to Apalachicola FL from 20 to 60 NM-Waters from
     Apalachicola to Destin FL from 20 to 60 NM.


&&

$$

NEAR TERM...BLOCK
SHORT TERM...BARRY
LONG TERM...BLOCK
AVIATION...FOURNIER
MARINE...BARRY
FIRE WEATHER...FOURNIER
HYDROLOGY...CJM






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