Areal Flood Advisory 7, NWS Mobile, AL

Area Forecast Discussion
National Weather Service Mobile AL
1050 PM CDT Wed Mar 24 2021

.NEAR TERM /Now Through Friday/...An upper trof, the axis of which
extends mainly from New Mexico into northern Mexico, advances into
Oklahoma/Texas overnight.  The upper trof takes on a negative tilt
on Thursday while moving to the mid Mississippi River valley, then
continues into the eastern Great Lakes through Friday morning.  An
associated surface low brings a cold front across the lower
Mississippi River valley Thursday afternoon which then moves slowly
through the forecast area Thursday night.  Within a southwest flow
aloft over the region, a series of shortwaves shift from currently
over the forecast area lift well north of the area overnight, and
expect current high coverage of precipitation over much of the
area to gradually diminish.  Model soundings show that
unfavorable low level lapse rates develop overnight within at
least the lowest 2-3 kft, along with a mid level cap forming.
During the overnight hours, model soundings also show significant
drying occurring above 750 mb, likely in response to subsidence in
the wake of the shortwaves exiting to the north. The low level
jet will have meanwhile strengthened significantly overnight to
35-45 knots. See that there is some potential for a strong storm
or two until about midnight, after which trends seen in model
soundings should bring about a temporary end to the potential for
strong storms.

As the upper trof takes on a negative tilt, this brings a region
of strong deep layer lift mainly across much of Mississippi and
northern Alabama through the day on Thursday. While the strongest
deep layer lift is expected to pass mainly northwest and north of
the area, the forecast area will still see sufficient forcing
generally north of I-65 to support likely to categorical pops
during the day, with chance pops expected over the remaining
portion. In response to the deep layer lift along with daytime
heating, model soundings show the unfavorable low level lapse
rates/mid level cap are quickly eroded/overcome north of I-65 in
the morning. Over the remainder of the area, there's uncertainty
with how long the mid level cap will be able to suppress deep
convection. MLCAPE values of 2000-2500 J/kg will be realized by
mid morning over Wayne and Choctaw counties and over the portion
of the area generally north of I-65 by midday, while further east
MLCAPE values of 1500-2000 J/kg are possible. The low level jet
reaches a peak of 40-55 knots by midday Thursday which continues
through the afternoon hours. This results in very high favorable
shear profiles along with 0-3 km helicity values of 200-400 m2/s2.
For this environment, the Storm Prediction Center has an
Enhanced/Moderate Risk over the northwesternmost portion of the
forecast area on Thursday (with a Slight Risk for most of the
remainder of the area), and this higher level risk area could be
expanded to include more of the area, depending on the strength of
deep layer forcing.

The cold front which meanwhile approached from the west will move
slowly through the area Thursday night, and until the strong low
level jet/instability subsides, this will support at least some
continued potential for severe storm development through the early
evening hours, after which the potential decreases quickly. For
Friday, the weak frontal boundary returns northward through the
area with a light southerly flow developing, and have gone with
slight chance to chance pops. Have continued with a Wind Advisory
for the entire area from 4 am to 10 pm Thursday due to southerly
winds of 15 to 25 mph with gusts to 40 mph possible. A Flash Flood
Watch remains in effect for southeast Mississippi and
southwestern Alabama, although have cancelled the watch for
Baldwin county Alabama and Escambia county Florida as additional
rainfall amounts are not expected to support a flooding risk.
While some heavy rain is possible through shortly after midnight,
rainfall amounts overnight trend lower, and also look lower
overall for Thursday into Thursday night. Consequently, the
remainder of the Flash Flood Watch may be able to be cancelled
later on tonight. A High Risk of rip currents continues through
the weekend, and a High Surf Advisory is in effect until 7 am
Friday. A Coastal Flood Advisory also remains in effect until 1 am
Friday. /29

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Flash Flood Watch through late Thursday night for ALZ051>053-261-
     263-265.

     Wind Advisory from 4 AM to 10 PM CDT Thursday for ALZ051>060-
     261>266.

     Coastal Flood Advisory until 1 AM CDT Friday for ALZ263>266.

     High Rip Current Risk through Sunday afternoon for ALZ265-266.

     High Surf Advisory until 7 AM CDT Friday for ALZ265-266.

FL...Wind Advisory from 4 AM to 10 PM CDT Thursday for FLZ201>206.

     Coastal Flood Advisory until 1 AM CDT Friday for FLZ202-204.

     High Rip Current Risk through Sunday afternoon for FLZ202-204-
     206.

     High Surf Advisory until 7 AM CDT Friday for FLZ202-204-206.

MS...Flash Flood Watch through late Thursday night for MSZ067-075-076-
     078-079.

     Wind Advisory from 4 AM to 10 PM CDT Thursday for MSZ067-075-076-
     078-079.

GM...Small Craft Advisory until 7 AM CDT Friday for GMZ630>632-650-
     655-670-675.

     Small Craft Advisory from 4 AM Thursday to 7 AM CDT Friday for
     GMZ633>636.

&&

This product is also available on the web at:
http://weather.gov/mob

Special Weather Statement
National Weather Service Mobile AL
815 PM CDT Wed Mar 24 2021

MSZ075-078-250215-
Stone MS-Perry MS-
815 PM CDT Wed Mar 24 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT THE FOLLOWING
COUNTIES...SOUTHWESTERN PERRY AND STONE COUNTIES UNTIL 915 PM CDT...

At 814 PM CDT, the strong thunderstorms were located along a line
extending from 8 miles south of Poplarville to 8 miles west of Lyman,
and moving northeast at 45 mph.

Wind gusts of 40 mph will be possible with these storms.

Locations impacted include...
Wiggins, Perkinston and McHenry.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3091 8934 3091 8914 3122 8914 3091 8886
      3091 8889 3088 8888 3068 8903 3068 8924
      3065 8924 3065 8934
TIME...MOT...LOC 0114Z 205DEG 38KT 3072 8949 3048 8927

Special Weather Statement
National Weather Service Mobile AL
917 PM CDT Wed Mar 24 2021

MSZ075-076-078-079-250315-
Stone MS-Perry MS-Greene MS-George MS-
917 PM CDT Wed Mar 24 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT THE FOLLOWING
COUNTIES...WESTERN GEORGE...SOUTHERN PERRY...SOUTHWESTERN GREENE AND
STONE COUNTIES UNTIL 1015 PM CDT...

At 916 PM CDT, the strong thunderstorms were located along a line
extending from near McHenry to 7 miles east of Wiggins to 17 miles
southwest of Lucedale, and moving northeast at 40 mph.

Wind gusts of 40 mph will be possible with these storms.

Locations impacted include...
Wiggins, Lucedale, Perkinston, McHenry, Beaumont and McLain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3091 8917 3091 8914 3115 8914 3120 8868
      3100 8847 3073 8885 3073 8888 3072 8889
      3067 8903 3068 8924 3065 8924 3065 8932
TIME...MOT...LOC 0216Z 229DEG 34KT 3072 8918 3086 8901 3078 8884

Special Weather Statement
National Weather Service Mobile AL
1019 PM CDT Wed Mar 24 2021

ALZ052-261-MSZ076-079-250415-
Washington AL-Mobile Inland AL-Greene MS-George MS-
1019 PM CDT Wed Mar 24 2021

...A STRONG THUNDERSTORM WILL AFFECT THE FOLLOWING COUNTIES...
NORTHWESTERN MOBILE...SOUTHERN WASHINGTON...NORTHEASTERN GEORGE AND
SOUTHEASTERN GREENE COUNTIES UNTIL 1115 PM CDT...

At 1019 PM CDT, the strong thunderstorm was located 10 miles
southeast of Leakesville, moving northeast at 45 mph.

Wind gusts of 40 to 50 mph will be possible with this storm.

Locations impacted include...
Citronelle, Chatom, Leakesville, Deer Park, Tibbie, Calvert,
Fruitdale and McIntosh.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3153 8833 3126 8799 3115 8797 3089 8851
      3102 8866
TIME...MOT...LOC 0319Z 236DEG 38KT 3103 8846