Severe Thunderstorm Warning 100, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
304 PM CDT Sun Apr 19 2020

.UPDATE...
Long-term forecast update.

&&

.SHORT TERM...
/Updated at 1235 PM CDT Sun Apr 19 2020/

Multichannel water vapor imagery along with global model H500
fields agree in a well-defined trough over western Oklahoma that
extends southwest into Western Texas.

Hand surface analysis valid 17Z/12 pm reveals the warm front
extending from just south of Meridian, MS east to near Greenville
and extending further east to near Troy. The heavy morning
convection has produced outflow boundaries that have limited the
warm front's northward advancement.

12Z National surface analysis shows low pressure south of the Red
River in Central Texas with a warm front extending east
interacting with a coastal/marine warm front that extended from
Inland Southeast Texas across Northern Louisiana and further east
across the Southern Third of Alabama.

Expect the warm front to slowly advance north through mid
afternoon, likely remaining south of the I-20 corridor with it
potentially ending up from just south of Tuscaloosa to near
Sylacauga to near Auburn. The residual cold pool/mesoscale high
pressure to our east from the morning convection has helped to
stabilize the airmass in that area and while some destabilization
will likely occur, the risk over these areas has been reduced to
an extent, along with the risk across our northern counties based
upon updated information.

There appears to be a boundary stretched across our Central
Counties from Pickens County east to Randolph County that may be
a boundary existing off the surface as there is no surface
reflection evident. Convection continues to train from west to
east across this feature and remains a concern for continued
localized flooding. The persistent convection will inhibit further
northward advance of the warm front to the north of this feature.

To the south, convection has gradually intensified across our far
southeast counties along the warm front that extends from near
Troy east into northern Barbour County. The airmass consists of
temperatures in the 80s with dew points near 70 to the south
which is helping to provide robust instability for the convective
development. Expect this activity to continue with a growing risk
of strong to severe convection with time as the front gradually
lifts north over the next few hours. Additional convective
development is forecast further west across our southwest and
south-central counties as the warm front also advances further
north into these areas.

Convection across the Central Counties will continue to develop as
instability gradually increases with the continuing risk for large
hail. There will be a growing risk for damaging winds and
tornadoes as we progress through the afternoon near and south of
this activity closer to the surface warm front.

Heavy rainfall with localized flooding remains a concern as
morning convection easily dropped over 2-4 inches. Additional
convection over these areas will aggravate saturated soils and
will runoff causing additional flooding. The Jackson, MS 12Z
Sounding contained a precipitable water value of 1.55 inches and
that airmass is likely in place now across much of our forecast
area. Concern for the Metro Areas in Central Alabama persists as
the likely elevated boundary remains draped along the Interstate
20 corridor.

Conditions continue to favor the development for severe weather
across the southern half of our forecast area this afternoon and
evening with the highest potential across the southern third of
our forecast area.

05

.LONG TERM...
/Updated at 0245 PM CDT Sun Apr 19 2020/

Monday through Friday.

Following the passage of the current severe weather maker, all
eyes will be focused on the next dynamic system expected to make
an entrance by Thursday. Model guidance is coming into a little better
agreement in regards to timing and track of the shortwave trough
and associated surface low that will move off to our northwest.
Global models now present a timing for the possibility of severe
storms beginning early Thursday morning and lasting through the
Thursday evening across our far southeast counties. Based on
SBCAPE and 0-6km bulk shear values, at least the southern half of
Central Alabama could have yet another more significant chance of
severe storms with all types of severe weather possible. I've gone
ahead and increased confidence within the HWO and changed the
timing to primarily Thursday with the better timing agreement.
We'll start to focus exclusively on this event beginning with the
overnight shift tonight.

56/GDG

&&

.AVIATION...
18Z TAF Discussion.

Widespread TSRA will continue to highly impact terminals this
afternoon, in addition to low cigs and vis due to heavy rainfall
moving over terminal locations. IFR conditions can be expected
intermittently through the next six hours due to the persistent
thunderstorms. High wind gusts are also possible due to the
possibility of severe storms later this afternoon through the
evening hours, especially for KMGM and KTOI. Amendments will be
needed based on the development and movement of these storms as we
go through the overnight hours tonight.

Showers and storms will come to an end early Monday morning with
lingering low cloudiness and northwesterly surface winds.

56/GDG

&&

.FIRE WEATHER...

Multiple waves of showers and storms are expected through the
overnight hours and into the early morning hours on Monday. Dry
conditions should return for Monday afternoon with RH values well
above critical thresholds with very wet ground conditions.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     54  71  47  74  45 / 100  30   0   0   0
Anniston    55  73  48  75  47 / 100  20   0   0   0
Birmingham  55  73  50  76  50 / 100  10   0   0   0
Tuscaloosa  58  74  51  78  51 / 100   0   0   0   0
Calera      57  73  50  75  50 / 100  10   0   0   0
Auburn      57  73  51  75  50 / 100  20   0   0   0
Montgomery  61  75  52  79  52 / 100   0   0   0   0
Troy        62  78  54  79  53 / 100  10   0   0   0

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
Flash Flood Watch until 1 AM CDT Monday for the following
counties: Autauga...Barbour...Bibb...Bullock...Calhoun...
Chambers...Chilton...Clay...Cleburne...Coosa...Dallas...Elmore...
Fayette...Greene...Hale...Jefferson...Lamar...Lee...Lowndes...
Macon...Marengo...Montgomery...Perry...Pickens...Pike...
Randolph...Russell...Shelby...St. Clair...Sumter...Talladega...
Tallapoosa...Tuscaloosa...Walker.

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
305 PM CDT Sun Apr 19 2020

ALZ011>015-017>050-202315-
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-
305 PM CDT Sun Apr 19 2020

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 storms are likely this afternoon and overnight,
mainly from 3 PM CDT through 2 AM Monday. The greatest threat for
severe storms and the tornado threat should remain across the
southern half of Central Alabama or along and south of Sumter County
to Chilton County to Chambers County. Strong tornadoes, damaging
winds up to 80 mph and golf ball size will be possible in this area.
To the north, a few storms could produce damaging winds and quarter
size hail. Thunderstorms with heavy rainfall  may result in flash
flooding.

Minor flooding is forecast to occur along portions of the Tombigbee,
Black Warrior, Cahaba and Tallapoosa river basins. Please see flood
statements for specific details.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Minor flooding is forecast to occur along portions of the Tombigbee,
Black Warrior, Cahaba and Tallapoosa river basins. Please see flood
statements for specific details.

There is a threat of severe thunderstorms, including tornadoes,
across all of Central Alabama on Thursday.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management will be needed
today and tonight. Please follow all local, state, and CDC guidelines
in regards to travel.

Special Weather Statement
National Weather Service Birmingham AL
221 PM CDT Sun Apr 19 2020

ALZ030-031-191945-
Greene AL-Sumter AL-
221 PM CDT Sun Apr 19 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN GREENE AND SOUTHERN
SUMTER COUNTIES UNTIL 245 PM CDT...

At 221 PM CDT, Doppler radar was tracking a strong thunderstorm over
York, moving northeast at 50 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Livingston, York, Forkland, Walden Quarters, The University Of West
Alabama, Bluffport, Thornhill, Coatopa, Dug Hill, Tishabee, Old
Mallard Airport, Belmont, Lilita, McDowell, Bellamy and Birdine.

LAT...LON 3256 8839 3277 8787 3276 8787 3276 8785
      3271 8783 3264 8778 3264 8781 3262 8781
      3261 8779 3261 8776 3259 8774 3257 8777
      3258 8777 3258 8778 3256 8779 3238 8831
      3255 8839
TIME...MOT...LOC 1921Z 247DEG 45KT 3250 8828

15

Special Weather Statement
National Weather Service Birmingham AL
244 PM CDT Sun Apr 19 2020

ALZ031-032-192015-
Greene AL-Hale AL-
244 PM CDT Sun Apr 19 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN GREENE AND WEST
CENTRAL HALE COUNTIES UNTIL 315 PM CDT...

At 243 PM CDT, Doppler radar was tracking a strong thunderstorm over
Tishabee, or 8 miles east of Livingston, moving northeast at 50 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Forkland, Duffys Bend, Sawyerville, Thornhill, Greensboro Municipal
Airport, Walden Quarters, Wedgeworth, Tishabee, Evansville, Five
Points Intersection, Selden Lock And Dam and Birdine.

LAT...LON 3285 8774 3263 8757 3260 8789 3261 8787
      3262 8788 3262 8791 3263 8793 3261 8798
      3260 8804 3264 8808 3264 8806 3267 8806
      3269 8804 3269 8809
TIME...MOT...LOC 1943Z 247DEG 44KT 3262 8804

15

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
308 PM CDT SUN APR 19 2020

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

0720 AM     TSTM WND DMG     DADEVILLE               32.84N 85.76W
04/19/2020                   TALLAPOOSA         AL   EMERGENCY MNGR

            *** 1 INJ ***
            CORRECTS TIME ON PREVIOUS TSTM WND DMG
            REPORT FROM DADEVILLE. WIDESPREAD WIND
            DAMAGE IN DADEVILLE. AT LEAST ONE REPORTED
            MINOR INJURY.

&&

AS

Special Weather Statement
National Weather Service Birmingham AL
348 PM CDT Sun Apr 19 2020

ALZ030-031-192115-
Greene AL-Sumter AL-
348 PM CDT Sun Apr 19 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN GREENE AND SOUTHERN
SUMTER COUNTIES UNTIL 415 PM CDT...

At 348 PM CDT, Doppler radar was tracking a strong thunderstorm over
York, moving east at 45 mph.

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

Locations impacted include...
Livingston, York, Cuba, Forkland, Epes, Boyd, The University Of West
Alabama, Bluffport, Thornhill, Coatopa, Dug Hill, Tishabee, Old
Mallard Airport, Belmont, Lilita, McDowell and Five Points
Intersection.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3259 8838 3276 8794 3255 8780 3254 8780
      3253 8782 3254 8782 3255 8784 3254 8785
      3253 8784 3252 8791 3251 8792 3240 8837
      3247 8840
TIME...MOT...LOC 2048Z 249DEG 41KT 3252 8833

15

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
409 PM CDT SUN APR 19 2020

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

0530 AM     TSTM WND DMG     LAKE VIEW               33.28N 87.13W
04/19/2020                   TUSCALOOSA         AL   EMERGENCY MNGR

            TREES DOWN ON POWERLINES ON PHYLLIS DR IN
            LAKE VIEW. TIME ESTIMATED BY RADAR.

0710 AM     TSTM WND DMG     JACKSONS' GAP           32.88N 85.82W
04/19/2020                   TALLAPOOSA         AL   PUBLIC

            TREES DOWN IN JACKSONS GAP.

&&

Special Weather Statement
National Weather Service Birmingham AL
422 PM CDT Sun Apr 19 2020

ALZ039-192145-
Marengo AL-
422 PM CDT Sun Apr 19 2020

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MARENGO COUNTY UNTIL 445
PM CDT...

At 422 PM CDT, Doppler radar was tracking a strong thunderstorm over
Pennington, or 14 miles southwest of Linden, moving east at 50 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Linden, Thomaston, Myrtlewood, Dayton, Freddie Jones Field, Miller,
Pin Hook, Chickasaw State Park, Calvary, Half Acre and Octagon.

LAT...LON 3214 8804 3215 8802 3218 8801 3224 8802
      3226 8801 3228 8802 3231 8798 3230 8797
      3231 8795 3228 8794 3229 8793 3231 8793
      3235 8799 3243 8764 3235 8760 3224 8757
      3217 8756 3211 8804
TIME...MOT...LOC 2122Z 255DEG 42KT 3222 8802

15