Special Marine Warning 255, NWS Mobile, AL

Area Forecast Discussion
National Weather Service Mobile AL
1208 PM CDT Sun Aug 15 2021

.NEAR TERM /Now Through Monday/...Weak upper level trough over the
northern Gulf of Mexico continues to disintegrate and shift
northwest as Tropical Storm Fred maneuvers around the western
periphery of the mid to upper level subtropical ridge draped
across the southwestern Atlantic.

For today, increasing shower and thunderstorm activity, generally
scattered to numerous coverage, is expected as we head into the
afternoon and evening hours in association with the weakening
upper level low, and increasing flux of moisture associated with
Fred. We can already see evidence of this activity shifting
northwest this morning over the marine areas and just beginning to
develop across coastal counties of AL/FL. Most of the activity
today should remain below severe limits, although with ample water
loading and within storm clusters/mergers, similar to yesterday
some gusty winds and heavy rainfall can be expected. PWATs will
generally become 2 to 2.2 inches, fostering heavy rainfall
potential in thunderstorms. SBCAPE/MLCAPE values will remain
similar to yesterday, peaking in the 1,500 to 2,000j/kg range.
DCAPE values will have decreased some owing to the moistening
atmospheric profile, but still maintain a general 500 to 800j/kg.
Heading into tonight, best shower and thunderstorm coverage will
remain over southwestern AL into southeastern MS, and along and
south of the immediate coast of AL/FL. Some heavier rainfall can
be expected with these, particularly nearer the coast as Fred
starts to enter the picture with its outer rainbands. Fred is
discussed more below for tomorrows weather, along with the
expected hazards/impacts to the region. Forecast highs today will
reach the upper 80's and lower 90's, with middle to upper 80's
Monday. Lows tonight will be in the lower to middle 70's.

Our main feature of interest is Tropical Storm Fred
heading into Monday. Fred was a remnant low last night into early
this morning, but has since redeveloped its low level center.
This is both evident via hurricane hunter reconnaissance data and
visible satellite imagery this morning. Given the low level
center reformed north and east of the previous estimated position,
the forecast path of Fred has shifted to the east. This will
limit greatest impacts along and southeast of the I-65 corridor,
and the immediate coast of AL into the marine zones. Fred will
bring multiple hazards to the region Monday, each detailed below.

Flash flooding: A localized flash flood threat is setting up along
and to the north/east of the path of Fred. This appears most
likely to set up along and southeast of the I-65 corridor, with a
moderate threat for flash flooding across Okaloosa, Covington, and
Crenshaw counties. It is across the FL panhandle into our far
southeastern AL counties that we presently have a flash flood
watch for starting overnight tonight through Tuesday early
afternoon. Rainfall amounts of generally less than an inch are
expected west of the I-65 corridor, with 2 to 4 inches along and
east of the I-65 corridor. Locally higher totals to 6+ inches
is possible farther southeast over Okaloosa county.

Coastal and Marine Hazards: A high surf warning remains in effect
across our coastal FL panhandle counties for large breaking waves
of 10 to 15ft, whereas a high surf advisory is in place for
coastal Mobile and coastal Baldwin counties for large breaking
waves of 5 to 8 feet. Both of these are in effect from 7pm this
evening through 6am Tuesday.

A coastal flood advisory is in place for coastal counties of AL/FL
panhandle from 7pm this evening through 1pm Tuesday for minor
inundation of low lying/favored spots along the immediate coast.
Additionally, a high risk of rip currents is in place starting
this evening and running through late Tuesday night for AL/FL
panhandle coasts.

A tropical storm warning was put into place for the eastern marine
zones along the FL coast out through 60nm, as well as inland to
include Okaloosa counties. A tropical storm watch remains in place
across the remaining FL counties, Escambia and Covington counties
in AL, and local bays and sounds in those areas. In the warning
area, winds of 35 to 45mph can be expected tomorrow afternoon and
evening through Tuesday morning, while in the watch area these
conditions remain possible but is contingent on the actual path of
Fred. Where tropical storm conditions are not expected over our
western marine zones including Mobile Bay and the Mississippi
Sound, a small craft advisory is in effect for winds upwards of
25kts gusting to 35kts.

Tornadoes: To the right and ahead of the path of Fred, isolated
tornadoes can not be ruled out with the outer rain bands of Fred.
This threat should be limited to the FL panhandle and south-
central AL, but is once again contingent on the path of Fred.

Summary: Tropical Storm Fred is a rapidly evolving situation, and
changes in the forecast path and intensity can result in large changes
in the forecast. We will likely have a better idea this afternoon
on Fred's ultimate path now that we have a better defined low
level center, and should see less shifts in the forecast track as
we move forward. These types of systems are always a headache, and
further updates will continue to be posted as Fred approaches the
northern Gulf coast. MM/25

&&

.AVIATION...
18Z issuance...Largely VFR conditions prevail through the period
outside of showers and storms. Underneath any storms, IFR
conditions may occur temporarily with respect to both visibility
and ceilings. For south-central AL into the Fl panhandle, expect
winds to shift and strengthen to 10 to 20kts from the
northeast/east early afternoon Monday. MM/25

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Tropical Storm Watch for ALZ059-060.

     Flash Flood Watch from 7 PM CDT this evening through Tuesday
     afternoon for ALZ058-060.

     Coastal Flood Advisory from 7 PM this evening to 1 PM CDT
     Tuesday for ALZ265-266.

     High Rip Current Risk from 7 PM CDT this evening through late
     Tuesday night for ALZ265-266.

     High Surf Advisory from 7 PM this evening to 6 AM CDT Tuesday
     for ALZ265-266.

FL...Tropical Storm Warning for FLZ205-206.

     Tropical Storm Watch for FLZ201>204.

     Flash Flood Watch from 7 PM CDT this evening through Tuesday
     afternoon for FLZ203>206.

     Coastal Flood Advisory from 7 PM this evening to 1 PM CDT
     Tuesday for FLZ202-204-206.

     High Rip Current Risk from 7 PM CDT this evening through late
     Tuesday night for FLZ202-204-206.

     High Surf Advisory from 7 PM this evening to 1 PM CDT Monday for
     FLZ202-204-206.

     High Surf Warning from 1 PM Monday to 6 AM CDT Tuesday for
     FLZ202-204-206.

MS...None.
GM...Small Craft Advisory from 10 PM this evening to 7 PM CDT Monday
     for GMZ630>633.

     Small Craft Advisory from 7 PM this evening to 7 AM CDT Tuesday
     for GMZ650-670.

     Tropical Storm Warning for GMZ635-636-655-675.

     Tropical Storm Watch for GMZ634.

&&

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