Severe Thunderstorm Warning 14, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
252 PM CDT Tue Mar 22 2022

.SHORT TERM...
/Updated at 1248 PM CDT Tue Mar 22 2022/

...Severe storms likely this afternoon and overnight...

Features of Interest.

A deep trough remains over the Northern and Central Plains with a
closed low over Central Kansas while broad ridging extended from
over the Western Caribbean Sea north to over the Great Lakes
region.

We will be watching an are of low pressure over Northern Louisiana
that will move northeast with time. This feature is associated
with a marine warm front that extended from near Jackson, MS
southeast into interior Southwest Alabama.

Through Tonight.

Clouds will continue to increase with time from the west as a
shortwave trough moves east within the broad upper trough. This
feature will provide sufficient forcing aloft to promote and
sustain a mesoscale convective system (MCS) that will move east
across the area later this afternoon through tonight. Strong wind
shear will promote embedded bowing segments and LEWP structures
that will pose a damaging wind and tornado risk within the
convective complex. Large hail will be a risk as well as upper
level height falls associated wit the approaching upper trough
result in steeping mid to upper level lapse rates. Additionally,
we continue to monitor the developing more discrete convection
over South-Central and Southeast Mississippi that may mature with
time as this activity moves northeast with times ahead of the
convective complex. These supercells will have the greatest
threat for tornadoes in addition to posing a damaging wind and
large hail risk as well.

The overall severe weather threat area will be maximized across
portions of our far west and southwest counties, where low-level
instability values are forecast to be the greatest. Activity will
move northeast within the line as it pushes east so effects will
be felt across our West-Central and much of our Central counties
as well late this afternoon and through tonight. Though
instability values look to gradually decrease through the night to
the north and east, isolated instances of damaging winds, large
hail and even a few tornadoes will remain possible given the
strong shear and sufficient buoyancy maintained through the
overnight hours.

We expect storm total rainfall amounts generally from 2-4 inches
from this event and we will have to closely monitor areas that
experience multiple storms, from any pre-MCS activity and then as
the line pushes through. Given how wet ground conditions are going
into this situation, we have issued a flood watch and are quite
concerned about localized flooding, particularly in areas that are
low-lying, poor drainage and urbanized locations. River flooding
looks to be a longer duration event, especially along the Black
Warrior and Tombigbee River Basins where some spots may see water
levels above flood stage for over a week to come.

Outside of the heavy convective activity, winds will continue to
increase out of the southeast at 10-20 mph, becoming 20-30 mph
with gusts to 40 mph at times as the gradient tightens further
between high pressure offshore of the Carolinas and low pressure
approaching from the west. Highs today will be in the mid to upper
70s areawide with some areas across the southeast reaching 80.
Winds will become southwesterly overnight and will remain breezy
with speeds from 10-20 mph at times. Lows will range from the
lower 50s northwest to the mid 60s southeast.

Wednesday.

A broad trough will remain over the Central portion of the country
and this slow eastward progression of the system will keep our
area under partly cloudy skies during the afternoon hours on
Wednesday despite much of the rain pushing east of the area during
the early to mid morning hours. I maintained low end PoP's far
east/southeast into late morning. Winds will be breezy at times
from the west at 7-14 mph. Highs will range from near 60 far
northwest to the mid 70s far southeast.

05

.LONG TERM...
/Updated at 0248 PM CDT Tue Mar 22 2022/

Aside from some lingering light showers in the far southeastern
counties Wednesday night, the remainder of the 7-day forecast will
be dry. We'll see a cool down toward the end of the week and into
the weekend, and then a warming trend early next week.

No substantial changes from the previous long term forecast.

/61/

Previous long-term discussion:
/Updated at 0300 AM CDT Tue Mar 22 2022/

Wednesday night through Monday.

A large, nearly cut off upper-level trough over the central and
eastern CONUS, will slowly move eastward Wednesday night and
Thursday. The associated dry slot will move over the region and
provide dry conditions behind a slow-moving cold front. Lingering
showers near the front should remain just outside our forecast area
across SE AL and SW GA.

The upper-level trough axis will finally shift eastward on Friday,
with a reinforcing push of cooler and drier air. Yet another
shortwave will dig into the Mid-Atlantic and Northeast states on
Saturday with continued cool northwesterly flow. A surface ridge
axis is expected to promote radiational cooling with the potential
for frost across the northern counties on Sunday morning. This will
be followed by significant warming trend for Monday as southwesterly
flow rapidly develops.

87/Grantham

&&

.AVIATION...
18Z TAF Discussion.

Flying conditions will deteriorate through the afternoon hours
from west to east as a convective complex moves east into the
area. Expect windy conditions at the surface with southeast winds
10-20 kt, increasing 20-30 kt with higher gusts at times even
outside of convection. Showers and thunderstorms will become
likely later this afternoon in the west, expanding east with time
with all modes of severe weather possible. Expect low CIGs
overnight with improving conditions through the morning hours on
Wednesday as most of the rain moves out by mid morning with only
some lingering showers far east.

05

&&

.FIRE WEATHER...

Strong to severe storms are likely this afternoon and tonight,
with gusty south to southeast winds and locally heavy rain. KBDI
values remain very low due to above normal rainfall this month.
Drier and more favorable burn conditions return by Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     61  69  40  64  39 / 100  50   0  10   0
Anniston    64  71  42  65  41 / 100  50  10  10   0
Birmingham  61  66  43  64  43 / 100  30   0   0   0
Tuscaloosa  57  64  42  66  42 / 100  20   0   0   0
Calera      62  67  44  66  43 / 100  30   0  10   0
Auburn      64  73  46  65  45 / 100  80  10  10  10
Montgomery  67  73  45  69  44 / 100  50  10  10   0
Troy        66  76  47  68  46 / 100  60  10  10   0

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
Wind Advisory until 7 AM CDT Wednesday for the following
counties: Autauga...Barbour...Bibb...Blount...Bullock...
Calhoun...Chambers...Cherokee...Chilton...Clay...Cleburne...
Coosa...Dallas...Elmore...Etowah...Fayette...Greene...Hale...
Jefferson...Lamar...Lee...Lowndes...Macon...Marengo...Marion...
Montgomery...Perry...Pickens...Pike...Randolph...Russell...
Shelby...St. Clair...Sumter...Talladega...Tallapoosa...
Tuscaloosa...Walker...Winston.

Flood Watch through Wednesday morning for the following
counties: Bibb...Blount...Chilton...Dallas...Fayette...Greene...
Hale...Jefferson...Lamar...Marengo...Marion...Perry...Pickens...
Shelby...St. Clair...Sumter...Tuscaloosa...Walker...Winston.

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
1049 AM CDT Tue Mar 22 2022

ALZ011>015-017>050-231900-
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-
1049 AM CDT Tue Mar 22 2022

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 this afternoon through
tonight across Central Alabama. Threats include tornadoes, damaging
wind gusts, and large hail.

Locally heavy rainfall is likely this afternoon through tonight. One
to four inches of rain is possible, with locally higher amounts in
the northwest. This could lead to flooding of low lying or poor
drainage areas.

Non-thunderstorm wind gusts up to 40 mph are possible across Central
Alabama today and tonight. This could lead to sporadic uprooted
trees and power outages.

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

River flooding is forecast for portions of the Tombigbee and Black
Warrior Rivers. Please refer to river products for specific
information.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management will likely be
needed this afternoon through tonight.