Severe Thunderstorm Warning 121, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
1255 PM CDT Thu May 18 2023

...New SHORT TERM, AVIATION...

.SHORT TERM...
(This afternoon through Friday)
Issued at 1247 PM CDT THU MAY 18 2023

A shortwave trough will move west to east across the Tennessee
Valley today which will foster the development of scattered to
numerous showers and thunderstorms across Central Alabama. The
trough and associated vort max are approaching the area from the
west and this will coincide with peak heating while PWATs range
from 1.5 to 1.6 inches. This dynamic support should result in
another afternoon where activity is greater in coverage than would
typically be seen from diurnal heating alone which will not only
result in Likely PoPs, but should also help to hold highs in the
upper 70s to lower 80s. Cooler mid-level air associated with the
shortwave trough in addition to 15-20 kts of eff. shear could
support a few stronger storms capable of producing mainly sub-
severe wind gusts and small hail, but organized severe weather is
not expected.

At the surface, high surface pressure is extending southwest along
the Mid-Atlantic region and will provide easterly boundary layer
flow tonight as a wedge front moves into the area. This will
produce a light 5 to 10 mph breeze overnight which should help to
reduce the potential for fog development, and will provide a
slightly drier airmass with overnight lows in the lower to mid
60s. The shortwave trough moves east of the area tomorrow, so
Central Alabama will briefly be under the effects of ridging which
will result in a more isolated, diurnally driven pattern to
convection tomorrow afternoon. Most areas will remain dry,
especially in the eastern half where the air will be drier, so
Slight Chance PoPs are generally focused west of I-65. Highs will
range from the mid/upper 70s northeast to lower 80s southwest.

86/Martin

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 257 AM CDT THU MAY 18 2023

Friday night...the frontal boundary will be approaching from the
northwest. PW values will be in the 90th percentile with weak
instability. Models show isolated activity remaining in the early
night from any convection that develops Friday afternoon...with a
low chance of further isolated convection overnight in the
northern half of the area.

Saturday...models are inconsistent on timing arrival of the main
area of rain with several models showing late morning to noon as
the expected arrival time. Instabilities pick up around
sunrise...and with weak upper level support...will edge scattered
rain and isolated thunderstorms into the northwest and central AL
beginning in the early morning. Coverage and intensity should
increase through the morning as the boundary moves into the state.
Not expecting anything too severe at this time...though the
strong storms could be expected. The boundary will move slowly to
the southeast. With PW values as high as they are, a slow moving
boundary, and light winds in the mid levels...this type of front
will more of a long soaking rain with embedded stronger
thunderstorms. Will need to keep an eye on any training cells and
watch for localized ponding or flooding.

Activity should end in the northwest by Saturday afternoon...and by
Saturday evening and early night...activity should be moving mostly
east of the state. Sunday...winds will quickly move to out of the
east as a large area of high pressure develops over the Ohio Valley.
This will bring slightly cooler and much drier air to the northern
half of the state for Sunday. The southern half of the state could
retain some of the moisture and may experience scattered diurnal
convection Sunday afternoon into early evening. Areas in the north
should be too dry for any development.

Monday...a nice easterly jet sets up from the Atlantic into the
state with the high pressure remaining over the Ohio Valley.
Moisture could rebound and diurnal showers and thunderstorms are
expected each afternoon through the middle of the workweek.
Temperatures will remain fairly steady each day with upper 70s to
mid 80s for a high...and mid 50s to lower 60s for a low.

24

&&

.AVIATION...
(18Z TAFS)
Issued at 1247 PM CDT THU MAY 18 2023

A shortwave trough will initiate a greater coverage of convection
this afternoon as it passes across the Tennessee Valley. The highest
coverage should develop near the northern terminals from roughly 21-
00Z. Convection will begin to wane after 01Z, but MVFR/IFR ceilings
will redevelop as a wedge front moves into the area. This wedge
front will also drive easterly sfc winds which will range from 5-10
kts overnight, and should mostly help to reduce fog development
despite the abundant ground moisture. Flight conditions will slowly
begin to improve late in this TAF period.

86/Martin

&&

.FIRE WEATHER...

Scattered to widespread showers and thunderstorms are expected to
develop Thursday and Friday afternoon with gradual clearing by the
evening. Moisture values will remain elevated with easterly 20 ft
winds setting up this afternoon. Saturday...a frontal boundary
will move northwest to southeast through the state beginning in
the early morning in the northwest and remaining through the
evening in the southeast.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     60  79  61  79 /  40  20  20  70
Anniston    62  78  63  80 /  50  20  20  70
Birmingham  64  80  65  81 /  40  20  20  60
Tuscaloosa  65  82  66  83 /  50  30  20  50
Calera      65  79  66  81 /  60  20  20  60
Auburn      64  78  64  81 /  60  10  10  50
Montgomery  66  82  66  85 /  60  20  10  50
Troy        65  82  65  86 /  60  30  10  40

&&

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

SHORT TERM...86/Martin
LONG TERM....24
AVIATION...86/Martin

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Special Weather Statement
National Weather Service Birmingham AL
202 PM CDT Thu May 18 2023

ALZ017-181945-
Blount AL-
202 PM CDT Thu May 18 2023

...A strong thunderstorm will impact portions of central Blount
County through 245 PM CDT...

At 201 PM CDT, Doppler radar was tracking a strong thunderstorm over
Cleveland. This storm was nearly stationary.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Oneonta, Blountsville, Cleveland, Locust Fork, Susan Moore, Allgood,
Fairview, Nectar, Rosa, Easley, Chamblees Mill, Fowler Spring and
Hendrix.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 3410 8639 3387 8646 3394 8674 3406 8669
      3405 8668 3407 8669 3408 8668 3409 8666
      3411 8665 3411 8664 3412 8663 3412 8660
      3415 8659
TIME...MOT...LOC 1901Z 018DEG 1KT 3398 8657

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

25/Owen

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
228 PM CDT THU MAY 18 2023

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

0200 PM     HAIL             2 SW CLEVELAND          33.98N 86.59W
05/18/2023  E1.00 INCH       BLOUNT             AL   PUBLIC

            REPORT OF QUARTER-SIZE HAIL NEAR CLEVELAND.

&&

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