Special Weather Statement, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
230 PM CDT Tue May 30 2017

.SHORT TERM...

Already beginning to see the change in a heights over the area and
this has resulted in convection mainly being seen in a confluence
zone between the front itself and a boundary that has been lifting
northward most of the day. The primary or more dominate outflow
has been moving north, but as of the last hour we are beginning to
see a development on the southern moving outflow from these
storms as well. This is typical of summer time thunderstorms and
will continue through the afternoon hours. We will likely see the
main axis shift now to the southern moving outflow as the northern
outflow has raced ahead of the storms and that northward motion
has begun to slow with the storms. Most of this convection will
dissipate with the loss of the daytime heating, but should stay in
and around the I-20 corridor.

16

.LONG TERM...
Wednesday through Monday.

The upper-level trough and embedded closed upper low in the Great
lakes/Ontario region will be lifting northeastward away from the
forecast area Wednesday, resulting in weak height rises over
Central Alabama and a transition to westerly to west-northwesterly
upper-level flow. The lack of upper-level forcing should result in
convection following the typical diurnal cycle. PWATs and 1000-500
mb mean RH values indicate the best coverage of scattered
afternoon convection should be in southern Central Alabama where
PWATs will be in the 1.5 to 1.7 inch range. Further north, deep
layer moisture will be more limited, but some convection may
develop on a weak surface boundary moving in from the north.

The upper-level pattern across the country will be fairly blocky
through the rest of the week, with a high amplitude ridge
extending northward from the Plains through the Canadian Prairies
to the Arctic. The blocking pattern shows some characteristics of
a rex block with a southern stream trough located south of the
ridge and some characteristics of an omega block with troughs over
eastern Canada and the northeast Pacific. Central Alabama will be
in a weakly forced, moist/humid pattern, with the potential for
occasional southern stream disturbances to eject out of the
southern stream trough over northern Mexico. Elevated moisture
values indicate generally elevated chances of diurnal summertime
scattered showers and storms, though exactly how elevated will
depend on weak disturbances and remnant boundaries. Wednesday
night, a back door cold front may move into northeast Alabama and
temporarily bring in some drier air in northeast Alabama into
Thursday, while also potentially serving as a trigger for activity
on Thursday. Meanwhile, increasing moisture in southwest Central
Alabama ahead of a southern stream disturbance should result in
fairly good coverage of showers/storms Thursday afternoon there.

As we move into the upcoming weekend, a strong Pacific jet moving
into the West Coast should allow the blocky pattern to start
moving again. This may allow the main southern stream trough to
move into Central Alabama by Sunday and allow for enhanced rain
chances by then. However, the latest ECMWF has trended much weaker
and slower with this trough. Will maintain likely rain chances on
Sunday for now but these may need to be adjusted if this new trend
holds. A front may also approach the area towards the beginning of
next week. Overall, through the extended period temperatures will
be close to normal, with highs in the 80s, with the typical
summertime risk of a few strong storms.

32/Davis

&&

.AVIATION...
18Z TAF Discussion.

Main boundary now north of all TAF sites. feel as though an
outflow will reverse trends over the next few hours and begin to
generate precipitation further south so included a period of tsra
for the northern sites. We continue to monitor for this trend over
the next 2 to 3 hours and adjust where needed.

16

&&

.FIRE WEATHER...

Scattered showers and storms will be possible each day as we
remain in a moist summer pattern across the area. Critical fire
weather conditions are not expected due to abundant low level
moisture.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     62  83  63  83  64 /  40  40  10  30  30
Anniston    63  83  63  84  65 /  30  30  10  30  30
Birmingham  65  85  66  84  68 /  20  30  10  40  30
Tuscaloosa  65  87  65  86  67 /  20  30  10  50  30
Calera      65  83  65  85  66 /  20  30  10  40  30
Auburn      65  83  66  83  67 /  20  40  20  40  30
Montgomery  66  86  68  87  69 /  20  50  20  50  30
Troy        65  87  65  86  66 /  20  40  20  50  30

&&

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

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
528 AM CDT Tue May 30 2017

ALZ011>015-017>050-311330-
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-
528 AM CDT Tue May 30 2017

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

.DAY ONE...Outlook through Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management is not
expected at this time.

08

Special Weather Statement
National Weather Service Birmingham AL
1241 PM CDT TUE MAY 30 2017

ALZ015-017-024-301830-
Walker AL-Jefferson AL-Blount AL-
1241 PM CDT TUE MAY 30 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN WALKER...SOUTHERN
BLOUNT AND NORTHEASTERN JEFFERSON COUNTIES UNTIL 130 PM CDT...

At 1241 PM CDT, Doppler radar was tracking strong thunderstorms
along a line extending from near Cordova to near Morris. Movement
was northeast at 35 mph.

Winds in excess of 40 mph will be possible with these storms.

Locations impacted include...
Jasper, Gardendale, Sumiton, Cordova, Dora, Dallas, Warrior,
Kimberly, Morris, Locust Fork, Parrish, Oakman, Trafford, Sipsey,
County Line, Rocky Hollow, Burnwell, Beloit, Arkadelphia and Lynns
Park.

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 3391 8708 3390 8710 3389 8709 3389 8701
      3387 8700 3386 8696 3387 8692 3390 8693
      3385 8639 3382 8643 3380 8657 3377 8658
      3369 8688 3373 8748 3392 8709 3392 8708
TIME...MOT...LOC 1741Z 256DEG 31KT 3374 8722 3374 8690

JH/05

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
304 PM CDT TUE MAY 30 2017

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

0205 PM     FLASH FLOOD      1 NNW OHATCHEE          33.80N 86.02W
05/30/2017                   CALHOUN            AL   PUBLIC

            VIDEO FROM SOCIAL MEDIA SHOWED HIGH,
            FAST-MOVING WATER CROSSING SPRING ROAD IN
            OHATCHEE.

&&

GMS

Special Weather Statement
National Weather Service Birmingham AL
347 PM CDT TUE MAY 30 2017

ALZ024-302115-
Jefferson AL-
347 PM CDT TUE MAY 30 2017

...SIGNIFICANT WEATHER ADVISORY FOR  UNTIL 415 PM CDT...

At 347 PM CDT, Doppler radar was tracking a strong thunderstorm over
Lipscomb, or near Bessemer, moving east at 10 mph.

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

Locations impacted include...
Birmingham, Hoover, Bessemer, Homewood, Hueytown, Fairfield,
Midfield, Brighton, Lipscomb, Ross Bridge, Bluff Park and Shannon.

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 3339 8697 3346 8696 3346 8683 3338 8683
TIME...MOT...LOC 2047Z 279DEG 10KT 3342 8693

87/GRANTHAM

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