Area Forecast Discussion
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FXUS62 KTAE 261247
AFDTAE

Area Forecast Discussion
National Weather Service Tallahassee FL
847 AM EDT Sat May 26 2018

.UPDATE...

The previous forecast generally remains on track for today, just
made some minor adjustments to reflect latest trends in
temperature and chances of showers/storms. Still expect highest
chances of showers and thunderstorms to be stretch from the inland
FL Panhandle into parts of SE Alabama and far SW Georgia today as
sea breeze forcing interacts with increasing deep layer moisture
(PW values near 2" this afternoon) and SBCAPE from 1500-2500 J/kg.
Less instability and deep layer moisture will result in decreasing
coverage of showers and thunderstorms farther east in our area.
High temperatures will be in the mid 80s across most of our area,
with lower 80s across parts of the FL Panhandle where
showers/storms are most widespread.

&&


.PREV DISCUSSION [626 AM EDT]...

.NEAR TERM [Through Today]...

Deep moisture will continue to increase today ahead of Alberto.
Preciptable water values are expected to rise into the 1.7-1.9
inch range by the end of the day. Scattered to numerous showers
and a few thunderstorms are expected to develop, similar to the
past couple of days. High temperatures will generally be in the
low to mid 80s.


.SHORT TERM [Tonight Through Monday]...

The main player in the short term is subtropical storm Alberto.
Alberto is forecast by the National Hurricane Center to begin its
trek northward from off the west coast of Cuba today and enter
the southern Gulf tonight heading toward the northern gulf coast
Monday. The exact timing of landfall and track remains uncertain
with the track error cone roughly stretching from Buras Louisiana
to Apalachicola Florida. Alberto is disorganized at this time and
several key players will impact it along the way: an upper trough
and associated energy, ridging to the north, and deep bursts of
convection possibly dragging the center slightly off track.
Regardless, one should not focus on the exact track but rather the
impacts.

Heavy rain is the main threat. 3-6 inches of total rainfall
through the event with locally higher amounts are expected. The
highest amounts will be west of the Apalachicola river in Florida
and portions of SE Alabama closest to the NHC track. These amounts
could cause urban flash flooding and some river flooding
especially where releases have occurred upstream or river rises
from past rainfalls. Please reference hydrology section below.

Tropical storm conditions will primarily be confined to the Gulf
waters west of Apalachicola and perhaps extreme western Florida
panhandle counties, depending on the eventual track.

Isolated tornadoes will be possible as the entire area will be on
the east and northeast side of the storm.

Minor coastal flooding is also a possibility, along with beach
erosion and a high risk of rip currents across all beaches over
the next several days.

The worst of the conditions will occur Sunday into early Monday.


.LONG TERM [Monday Night Through Saturday]...

Alberto will come ashore along the northern Gulf coast late Monday
into Monday night according to the latest NHC track. From there,
Alberto will continue northward over northern Alabama by Wednesday
morning then get caught up in the westerlies and move northeast at
an increasing speed and eventually absorbed in the flow by Friday.
A moist southerly fetch off the Gulf will keep rain chances
elevated through Thursday with a return to seasonal rain chances
Friday and Saturday and a return to 90s for highs after low/mid
80s through midweek due to rain and cloud cover.


.AVIATION...

[Through 12z Sunday] Some patchy low ceilings could briefly reduce
conditions to MVFR or IFR early this morning. Then, VFR conditions
are expected to prevail by mid-morning, although scattered to
numerous showers and thunderstorms are expected to develop across
the area today with temporary reductions in storms.


.MARINE...

Tropical Storm watches are in effect from coastal waters from
Ochlockonee Bay out 60NM, west to Destin. Small craft advisories
are in effect from the Suwanee river to Ochlockonee Bay including
Apalachee Bay beginning overnight tonight. Marine conditions will
begin to deteriorate as Alberto enters the Gulf of Mexico.
Tropical storm conditions will be possible as early as tomorrow
night. Mariners should remain in safe harbor until the storm
passes early next week.


.FIRE WEATHER...

Red flag conditions are not expected for the next several days.


.HYDROLOGY...

3-6" of widespread rain is currently forecast across the region.
The highest amounts are forecast to be west of the Apalachicola
and Chattahoochee rivers. Isolated higher amounts are possible in
these areas as well. There is the potential for these numbers to
come down depending upon the eventual positioning of a ribbon of
dry air aloft. This remains quite uncertain for now, so folks
should plan for the widespread 3-6".

Coastal flooding will be a possibility as Alberto moves north into
the Gulf. The greatest threat will be across Franklin and Wakulla
counties, and in the Sunday time frame. Current forecasts call for
the potential for 3 ft above MHHW (approx inundation) in these
areas, and 1-2 ft above elsewhere across the Big Bend and
Panhandle. These values are subject to change with the evolution
of the track and intensity of Alberto.

At this time, advertised rain amounts will be capable of causing
flash flooding, especially if occurring over a short period of
time. Additionally, the greatest potential for river flooding in
this event is across river basins already running above normal,
which include the Flint River, Chattahoochee River, Apalachicola
River, Choctawhatchee River, and Pea River.

The latest rainfall forecasts suggest that minor flooding is
possible on these rivers as early as Monday. Should heavier
rainfall amounts occur, more significant river flooding would be
possible.


.SPOTTER INFORMATION STATEMENT...

Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.

&&

.PRELIMINARY POINT TEMPS/POPS...

Tallahassee   86  72  82  73  85 /  50  50  80  60  50
Panama City   82  72  81  75  83 /  70  70  80  60  60
Dothan        85  70  81  72  84 /  70  30  80  70  70
Albany        86  71  82  72  86 /  60  30  80  70  70
Valdosta      86  70  82  71  85 /  40  40  80  70  70
Cross City    86  71  83  73  85 /  50  60  80  60  50
Apalachicola  82  73  81  76  83 /  70  70  80  60  50

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Tropical Storm Watch for Coastal Bay-Coastal Gulf-South Walton.

     High Rip Current Risk through late Tuesday night for Coastal Bay-
     Coastal Franklin-Coastal Gulf-South Walton.

GA...None.
AL...None.
GM...Small Craft Advisory from 5 AM Sunday to 8 AM EDT Monday for
     Apalachee Bay or Coastal Waters From Keaton Beach to
     Ochlockonee River FL out to 20 Nm-Coastal waters from
     Suwannee River to Keaton Beach FL out 20 NM.

     Tropical Storm Watch for Coastal Waters From Ochlockonee River
     to Apalachicola Fl out to 20 Nm-Coastal waters from Mexico
     Beach to Apalachicola FL out 20 NM-Coastal waters from
     Mexico Beach to Okaloosa Walton County Line FL out 20 NM-
     Waters from Suwannee River to Apalachicola FL from 20 to 60
     NM-Waters from Apalachicola to Mexico Beach FL from 20 to
     60 NM-Waters from Mexico Beach to Okaloosa Walton County
     Line FL from 20 to 60 NM.

&&

$$

UPDATE...Lahr
NEAR TERM...DVD
SHORT TERM...Scholl
LONG TERM...Scholl
AVIATION...DVD
MARINE...Scholl
FIRE WEATHER...DVD
HYDROLOGY...Harrigan


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