Special Weather Statement, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
312 PM CDT Wed Aug 12 2020

.SHORT TERM...
/Updated at 1218 PM CDT Wed Aug 12 2020/

Another day of scattered showers and thunderstorms across the
area...with activity expected to continue through the late
evening. Cloud cover has been increasing through the day...and
with the addition of the cirrus contamination from the system
across the MS River...temperatures should remain in the mid to
upper 90's this afternoon. Instabilities will be 1000-2000
J/kg...with DCAPE values once again be around 1200 across the
state. With the steep low level lapse rates and PW values around
1.7 to 1.9 in the 90th percentile for this time of year...could
expect one or two of these storms to be severe with a microburst
potential. A weak shortwave is expected to approach the area
overnight tonight. This will likely prevent convection from
weakening as quickly after sunset as in days past...with showers
and thunderstorms remaining through the early night tonight.
Patchy fog is possible in the early morning Thursday...especially
with the late mention of rainfall. Though due to the expected
cloud cover and winds remaining light...not expecting fog to be
more than patchy at best. Will update if needed.

Thursday...cloud cover will continue to increase through the morning
with rain chances increasing from west to east through the late
morning and early afternoon. By mid afternoon...most areas west
of I65 should begin to see some convection...with these storms
moving east through the rest of the afternoon. Instabilities will
be around 2000 J/kg through the afternoon with DCAPE values less
than 1000 J/kg. With a fairly weak wind profile and PW values
above the 90th percentile for this time of year...not expecting
much in the way of severe weather at this time. The greatest
threat with this activity is going to be heavy rain and
potentially high rainfall rates.

Temperatures...highs today will be in the low to mid 90's with heat
indices in between 100 and 104. Tonight...lows will be in the mid
70s...with highs on Thursday in the upper 80's to mid 90's. The only
areas expected to hit triple digits for heat indices are south of
I85.

24

.LONG TERM...
/Updated at 0239 PM CDT Wed Aug 12 2020/

Thursday night through Tuesday.

An active weather period expected Thursday night and Friday as the
main short wave trof tracks eastward across the area. Despite
presence of trof, 0-6km bulk shear values remain near or just
below 20 knots and mid level lapse rates are not impressive, so
thunderstorm activity should remain below severe limits. Rain
chances will decrease over the weekend as the upper trof axis
shifts east of Alabama. A broad upper trof will establish itself
over the eastern United States next week, with Alabama staying on
the drier and slightly cooler side of the trof axis.

58/rose

Previous long-term discussion:
/Updated at 0357 AM CDT Wed Aug 12 2020/

Thursday night through Tuesday.

An upper-level trough will continue to affect the region Thursday
night through Saturday as it moves very slowly eastward. Deep-layer
cyclonic flow will provide adequate lift for convection to continue
through the overnight hours on Thursday night into Friday morning.
Coverage will increase with daytime heating on Friday, with
multiple bands of showers and storms expected.

The trough should be positioned axis directly over Central Alabama
on Saturday, and bulk of the rainfall should occur across the
eastern two-thirds of our area, with a decrease in activity for the
west. A general trend of falling rain chances should continue for
Sunday through Tuesday as the system moves away to the east, unless
the GFS is correct with its depiction of MCS activity within
northwest flow on Monday.

87/Grantham

&&

.AVIATION...
18Z TAF Discussion.

Scattered thunderstorms will be possible this afternoon through
the early night. Confidence is low on timing and coverage...so
left mention out of each TAF for now...and will update if storms
develop in the vicinity. The exception is KASN and KANB who have
VCTS for a couple of hours with ongoing convection nearby.
Overnight...fog development is possible...but due to anticipated
cloud cover and light winds...have left mention out of each TAF.
Once the location of thunderstorm activity is known this
evening...will be able to better determine fog extent for the
early morning. Thursday...showers and thunderstorms will move in
from the west through the late morning.

24

&&

.FIRE WEATHER...

Rain chances will increase Thursday and Friday as an upper level
impulse moves across the region. The increase in cloud cover and
rain will result in cooler daytime temperatures and higher afternoon
humidity values. A drying trend should begin on Saturday and continue
into early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     71  92  71  86  70 /  40  70  70  80  60
Anniston    73  93  72  87  71 /  40  70  60  80  60
Birmingham  74  91  73  87  72 /  40  70  70  80  50
Tuscaloosa  74  91  74  88  73 /  40  70  70  80  40
Calera      72  91  72  86  71 /  40  70  70  80  50
Auburn      73  91  72  86  71 /  40  70  50  80  60
Montgomery  75  94  75  90  73 /  30  70  50  80  60
Troy        74  94  73  88  72 /  30  60  50  80  70

&&

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

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
403 AM CDT Wed Aug 12 2020

ALZ011>015-017>050-131215-
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-
403 AM CDT Wed Aug 12 2020

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

.DAY ONE...Outlook through Tonight.

Isolated strong to severe thunderstorms are possible this afternoon
and early evening. Brief damaging wind gusts of 60 mph and hail up to
quarter size could occur.

Heat indices may approach 105 degrees in a few locations this
afternoon. Take extra precautions while outside.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management may be needed
this afternoon and evening. Please follow all local, state, and CDC
guidelines in regards to travel.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
606 PM CDT WED AUG 12 2020

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

0536 PM     HAIL             3 ENE MARVYN            32.45N 85.31W
08/12/2020  E0.25 INCH       RUSSELL            AL   PUBLIC

&&

MAL

Special Weather Statement
National Weather Service Birmingham AL
617 PM CDT Wed Aug 12 2020

ALZ015-024-122345-
Walker AL-Jefferson AL-
617 PM CDT Wed Aug 12 2020

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL WALKER AND NORTH
CENTRAL JEFFERSON COUNTIES UNTIL 645 PM CDT...

At 617 PM CDT, Doppler radar was tracking a strong thunderstorm over
Burnwell, or over Dora. This storm was nearly stationary.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Sumiton, Cordova, Dora, Adamsville, Graysville, West Jefferson, Rocky
Hollow, Burnwell, Beloit, Quinton, Sayre, Barney and Miller Steam
Plant.

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.

&&

LAT...LON 3381 8704 3367 8694 3362 8706 3365 8714
      3376 8717
TIME...MOT...LOC 2317Z 110DEG 2KT 3371 8708

89^GSatterwhite

Special Weather Statement
National Weather Service Birmingham AL
620 PM CDT Wed Aug 12 2020

ALZ023-122345-
Tuscaloosa AL-
620 PM CDT Wed Aug 12 2020

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL TUSCALOOSA COUNTY UNTIL
645 PM CDT...

At 620 PM CDT, Doppler radar was tracking a strong thunderstorm over
Holt. This storm was nearly stationary.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Northeastern Tuscaloosa, Northport, Holt, Deerlick Creek Campgrounds,
Lake Nicol, Lake Tuscaloosa Dam, Sexton Bend, Lake Nicol Park, Holt
Lock And Dam, Lake Harris and Lake Tuscaloosa.

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.

&&

LAT...LON 3330 8740 3328 8740 3322 8746 3322 8753
      3324 8755 3330 8756 3335 8752 3337 8744
TIME...MOT...LOC 2320Z 110DEG 2KT 3329 8749

89^GSatterwhite

Special Weather Statement
National Weather Service Birmingham AL
621 PM CDT Wed Aug 12 2020

ALZ031-130000-
Greene AL-
621 PM CDT Wed Aug 12 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL GREENE COUNTY UNTIL
700 PM CDT...

At 621 PM CDT, Doppler radar was tracking a strong thunderstorm near
Union, or 10 miles northwest of Eutaw, moving northeast at 10 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Union, Mantua, Snoddy and Clinton.

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.

&&

LAT...LON 3288 8805 3300 8807 3310 8791 3305 8784
      3293 8785
TIME...MOT...LOC 2321Z 239DEG 8KT 3296 8800

89^GSatterwhite

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