Special Weather Statement, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
651 PM CDT Mon May 3 2021

.UPDATE...
For 00Z Aviation.

&&

.SHORT TERM...
/Updated at 0100 PM CDT Mon May 03 2021/
Through Tuesday.

Showers and storms have blossomed on radar over the past couple of
hours in response to destabilizing conditions at the surface,
along with steep lapse rates aloft. A persistent low-level jet of
45 to 50 knots at 850mb along with 3000-3500 J/kg of SBCAPE are
more than sufficient ingredients to sustain storm updrafts this
afternoon. Large hail and damaging straight-line winds will be the
primary threat but a tornado can't be ruled out, especially in
regards to storms that may interact with mesoscale boundaries.
With the summer-like atmospheric conditions at the surface and
pulse-type storms this afternoon, an updraft could get just enough
additional shear from an old outflow boundary for a tornado to
form. That will certainly bear watching as we go through the
afternoon. The forecast includes likely rain chances through the
early evening hours, then gradually decreasing in coverage. High-
res guidance is hinting at the possibility of some storms lasting
a bit longer toward midnight, so I wouldn't be surprised if an
update may be needed at some point to keep rain chances going a
bit longer.

The more significant severe weather threat will materialize during
the day on Tuesday. Confidence in terms of the severe weather
parameters available for severe storms remains fairly high, but
uncertainties remain in terms of where the severe storms will
develop and propagate as we go through the day. Mesoscale factors
will remain in play, and some high res guidance is hinting at
widespread shower and storm activity during the morning hours. As
is the case with any QLCS or MCS activity, we'll have to closely
monitor the radar trends through the overnight hours in order to
better determine timing of the severe storms as they move through
the area. If we don't get as much morning convection,
destabilization should easily occur and we could get cellular
severe storm development out ahead of what may become our QLCS
that is expected to move across Alabama during the day on Tuesday.
Stay tuned for subsequent mesoscale updates as we go throughout
the evening and overnight hours. Storms should move south of
Central Alabama by late evening, followed by cooler and drier air
moving southward behind the warm front.

56/GDG

.LONG TERM...
/Updated at 0100 AM CDT Mon May 03 2021/

Wednesday through Sunday.

The main trough axis continues to move east of our area early
Wednesday morning. The frontal boundary takes its time getting out
of the area, however, so expect lingering showers across the
southeast through the day, though any thunderstorm chance will be
dwindling as we transition to more of a zonal flow aloft and see
slight amplification of the 850mb ridge int he wake of the trough.

The zonal flow becomes more of a northwesterly flow aloft Thursday
into Friday as another impulse digs out a trough across the Eastern
CONUS. Model guidance still varies somewhat on if this trough will
reach far enough south to bring any chance of rain Thursday night.
For now, will stick closer to the Euro solution, which has better
ensemble agreement, keeping the area dry through Saturday with low
level ridging building across the Gulf States.

A weak upper level shortwave trough slides across the Central Plains
and develops a surface low Saturday night. This low is expected
to slide quickly eastward across the Ohio Valley Sunday morning
through the afternoon, draping a frontal boundary through the MS
Valley. Model guidance varies on the strength of the ridge and
just how far south the frontal boundary reaches by Sunday, so I've
kept rain/thunderstorm chances around 30-40% for Sunday afternoon
across the northern half of Central AL for now. This forecast
will likely change in coming days as we hopefully start to see
more model agreement.

25/Owen

&&

.AVIATION...
00Z TAF Discussion.

A few areas of thunderstorms are ongoing at the beginning of the
forecast period, with impacts possible at MGM and TOI this
evening. Will need to watch the northern edge of activity, as it
is possible it could impact EET before weakening. Stronger storms
could produce heavy rainfall and vis reductions, along with
frequent lightning and hail. Cannot rule out a strong wind gust.

Elsewhere, skies are clearing with winds out of the south to
southwest at 5-10kts. This activity will continue to diminish and
shift eastward, leading to a lull in rain activity for much of the
area overnight. Moist low level southerly flow will continue, and
expect low cigs to develop overnight, with MVFR/IFR heights. The
next round of showers and storms could arrive as early sunrise
Tuesday morning, and will include a prob30 for this activity.

Through the day, the chances for TSRA increase, along with severe
storm potential. Winds will remain from the south to southwest,
with wind gusts up to 22kts, with high-end MVFR/VFR cigs.

Note: AMD NOT SKED until further notice at KASN due to ongoing
equipment issues.

14

&&

.FIRE WEATHER...

Another round of scattered to numerous showers and storms are
expected today, and again on Tuesday before a cold front moves
through the day. Winds will increase from the south and become
southwesterly today. Speeds of 10-12mph are possible today. Drier
air arrives for Thursday and Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     68  82  60  75  48 /  40 100  90  20   0
Anniston    68  82  63  77  51 /  30 100 100  30   0
Birmingham  71  82  63  76  52 /  40 100  90  20   0
Tuscaloosa  72  83  61  77  52 /  40 100  70  10   0
Calera      70  81  64  76  53 /  30 100  90  20   0
Auburn      68  81  66  77  56 /  40  90  90  50  10
Montgomery  72  85  69  80  57 /  40  80 100  50  10
Troy        72  85  69  80  58 /  40  70  90  70  10

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
None.

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
620 PM CDT Mon May 3 2021

ALZ011>015-017>050-050230-
Marion-Lamar-Fayette-Winston-Walker-Blount-Etowah-Calhoun-Cherokee-
Cleburne-Pickens-Tuscaloosa-Jefferson-Shelby-St. Clair-Talladega-
Clay-Randolph-Sumter-Greene-Hale-Perry-Bibb-Chilton-Coosa-Tallapoosa-
Chambers-Marengo-Dallas-Autauga-Lowndes-Elmore-Montgomery-Macon-
Bullock-Lee-Russell-Pike-Barbour-
620 PM CDT Mon May 3 2021

This Hazardous Weather Outlook is for the counties served by the
National Weather Service office in Birmingham.

.DAY ONE...Outlook through Tonight.

Strong to severe thunderstorms are possible through 10 pm for the
southeastern half of Central Alabama. Threats include damaging winds
up to 60 mph and large hail. An isolated tornado cannot be ruled
out.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Strong to severe thunderstorms are possible Tuesday and Tuesday
evening across the all of Central Alabama. Threats include damaging
winds up to 70 mph, large hail and isolated tornadoes.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management may be
needed this evening and again on Tuesday.

Special Weather Statement
National Weather Service Birmingham AL
836 PM CDT Mon May 3 2021

ALZ025-034-035-040215-
Chilton AL-Bibb AL-Shelby AL-
836 PM CDT Mon May 3 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN CHILTON...
SOUTHWESTERN SHELBY AND EAST CENTRAL BIBB COUNTIES UNTIL 915 PM
CDT...

At 836 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Ashby to near Chilton County Motor Sports
Park. Movement was northeast at 20 mph.

Half inch hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Alabaster, Calera, Montevallo, Jemison, Thorsby, Wilton, Ashby,
Brierfield Ironworks Park, American Village, University Of
Montevallo, Chilton County Motor Sports Park, Randolph, Minooka Park,
Six Mile, Alabaster Veterans Park and Dogwood.

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.

&&

A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
central Alabama.

LAT...LON 3321 8684 3301 8661 3285 8686 3298 8706
TIME...MOT...LOC 0136Z 226DEG 19KT 3300 8698 3290 8687

32/Davis

Special Weather Statement
National Weather Service Birmingham AL
859 PM CDT Mon May 3 2021

ALZ045-047-048-040245-
Lee AL-Macon AL-Russell AL-
859 PM CDT Mon May 3 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LEE...SOUTHEASTERN
MACON AND NORTHERN RUSSELL COUNTIES UNTIL 945 PM CDT...

At 859 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Davisville to near Griffen Mill. Movement
was east at 30 mph.

Half inch hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Phenix City, Hurtsboro, Russell County Sports Complex, Uchee, Seale,
Ladonia, Beauregard, Davisville, Society Hill, Griffen Mill,
Warriorstand, Creek Stand, Hatchechubbe, Fort Mitchell, Ladonia
Sports Complex, Marvyn, Phenix Drag Strip and Parkmanville.

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.

&&

A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
southeastern and east central Alabama.

LAT...LON 3241 8498 3239 8497 3238 8499 3238 8497
      3237 8499 3236 8498 3234 8501 3233 8501
      3217 8541 3218 8543 3223 8544 3223 8556
      3231 8575 3258 8532 3246 8500 3245 8499
      3244 8497 3242 8496
TIME...MOT...LOC 0159Z 289DEG 24KT 3229 8565 3245 8524

32/Davis

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
919 PM CDT MON MAY 3 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 PM     FLASH FLOOD      SPEIGNER                32.58N 86.34W
05/03/2021                   ELMORE             AL   EMERGENCY MNGR

            RESIDENCE PARTIALLY UNDERWATER ALONG HWY
            143.

&&

TG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
923 PM CDT MON MAY 3 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 PM     FLASH FLOOD      2 NNW TALLAPOOSA LAKES  32.44N 86.14W
05/03/2021                   ELMORE             AL   EMERGENCY MNGR

            WATER OVER PORTION OF RIFLE RANGE RD NEAR
            OLD RIFLE RANGE RD.

&&

TG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
927 PM CDT MON MAY 3 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 PM     FLASH FLOOD      1 S WETUMPKA MUNI AIRPO 32.52N 86.33W
05/03/2021                   ELMORE             AL   EMERGENCY MNGR

            RESIDENT UNABLE TO LEAVE THEIR HOME ALONG
            UPPER GIBSON TOWN RD DUE TO FLOODING OUTSIDE
            THE RESIDENCE. WATER WAS NOT INSIDE THE
            HOME.

&&

TG

Special Weather Statement
National Weather Service Birmingham AL
931 PM CDT Mon May 3 2021

ALZ025-040330-
Shelby AL-
931 PM CDT Mon May 3 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL SHELBY COUNTY UNTIL 1030
PM CDT...

At 931 PM CDT, Doppler radar was tracking a strong thunderstorm over
Shelby County Airport, or near Alabaster, moving northeast at 20 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Hoover, Alabaster, Pelham, Helena, Calera, Chelsea, Montevallo,
Indian Springs Village, American Village, Oak Mountain State Park,
Maylene, Oak Mountain Amphitheater, Riverchase, Shelby County
Airport, Meadowbrook, Joe Tucker Park, Camp Branch, Hoover Veterans
Park, Siluria and Alabaster Veterans Park.

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.

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

&&

A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
central Alabama.

LAT...LON 3334 8652 3308 8674 3315 8694 3333 8686
      3333 8683 3336 8683 3336 8681 3337 8680
      3337 8678 3339 8678 3339 8676 3341 8675
TIME...MOT...LOC 0231Z 209DEG 15KT 3317 8681

32/Davis