Severe Thunderstorm Warning 51, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
1052 PM CDT Fri Apr 15 2022

.UPDATE...
MESOSCALE UPDATE.

&&

.SHORT TERM...
/Updated at 1042 PM CDT Fri Apr 15 2022/

A surface warm front was located near the Alabama Mississippi
state line late this evening. This boundary exhibited a rather
strong gradient concerning moisture. East of the front (cooler
side), surface dew points still remain in the 40s in most
locations. Although these have increased from the very dry
conditions this afternoon, it will be a continued slow rise
overnight. A low level jet interacting with an EML has kicked off
thunderstorms over Arkansas and Mississippi this evening. The low
level jet (35-40kts) will translate eastward overnight. Have
increased rain chances overnight west and also adjusted the higher
pops slightly south. The instability overnight should be elevated
but some will be very near the surface warm front. The instability
and shear parameters would support a marginal wind and hail
threat. Will continue the mention overnight and where this ends up
will play a role in what ultimately plays out Saturday.

75

Previous short-term discussion:
/Updated at 0657 PM CDT Fri Apr 15 2022/

A warm front was near the Mississippi state line early this
evening. The front has a very fine line of instability west to
east across the boundary. Increased Bulk Shear was also along this
axis and will spread eastward slowly overnight. Low level jet
develops within a few hours and migrates from Mississippi into
north and west Alabama. Overall moisture was still quite limited
over Central Alabama and will only slowly increase the next few
hours. The 00z BMX Raob has a EML with hefty lapse rates above it.
Will increase pops the next few hours near the state line. Still
anticipating an impulse to move northwest to southeast later
tonight. The threat of severe with a few storms this evening is
very low, but some small hail or wind gusts 30-40 mph are
possible. Better chances of severe storms start later tonight as
several waves will affect the region through early Monday.

75

Previous short-term discussion:
/Updated at 0320 AM CDT Fri Apr 15 2022/

Short Term.

Through Saturday.

A great day in store today across the area, with sunny skies and
temperatures rising into the upper 70s to low 80s. Clouds will be
on the increase this afternoon across the north as we will be in
a northwest flow aloft. At the same time we will see a warm front
lift northward as the high pressure slides eastward. By Midnight a
good portion of the area will be in the warm core and see
dewpoints quite high across the area. At the same time a MCS will
have developed during the peak heating of the day across the
Missouri Valley along the cold front. This MCS and associated
outflow will slide southward into the northern half of the area
after 1 AM and then spread south through the overnight and into
the day Saturday. As it encounters the airmass over Central
Alabama, there should be enough to keep the steam of the system
going and not totally squash the stronger storms. Thus look for
the MCS to maintain is strength as it moves into the region. So it
will likely be a loud overnight period for some, with strong to
marginally severe storms possible. The main threats for
overnight/Saturday will be damaging winds and large hail. Heavy
rainfall will accompany the the storms as well, but the
progressive nature of the system should be enough to limit
widespread issues.

This MCS will likely temper temperatures on Saturday so adjusted
downward a touch in the central sections of the area. The far
south may hit their highs around lunch, while the north may see
their highs after 5 pm, with additional clearing. Continued with
severe mention in the HWO but extended the time of concern.

16

.LONG TERM...
/Updated at 0256 PM CDT Fri Apr 15 2022/

Some spread in the guidance regarding PoPs for Saturday night,
with the CAMs being much drier than the non-CAMs. This will be
dependent on how far south the outflow boundary from Saturday
morning's MCS pushes. Will keep PoPs in the lower end chance
category for now. No change to the forecast reasoning for the
severe threat Sunday afternoon and Sunday night. May need to bump
the risk area a bit further north if trends continue, but this
will again depend on the outflow boundary from Saturday's MCS
which will serve as an effective warm front. Forecast hodographs
continue to suggest the tornado threat is minimal, unless the wave
of low pressure ends up being stronger than currently forecast.
The rest of the forecast looks dry; will have to monitor for
patchy frost potential in the cooler northeastern valleys Tuesday
and Wednesday mornings.

32/Davis

Previous long-term discussion:
/Updated at 0320 AM CDT Fri Apr 15 2022/

Saturday night through Thursday.

A stalled front is expected to be located over the southern
portions of the forecast area Saturday night. A brief lull in
convection should occur in Saturday evening between shortwaves
embedded within westerly flow aloft, but this will change on
Sunday. The combination of the upstream shortwave moving into the
Southern Plains and increasing upper-level diffluence will support
an upswing in shower and thunderstorm activity Sunday morning
from west to east. This activity should be focused near and north
of the stalled front where southwesterly 850mb flow will
contribute to isentropic lift. Destabilization appears likely by
afternoon south of the front while upper-level support for warm
sector convection continues to increase. Deep-layer shear around
40 knots appears supportive of strong to severe storms capable of
producing damaging winds and large hail across our southern
counties in the afternoon and early evening. Upscale growth into a
cluster or bowing segments may occur.

A period of mostly dry weather appears likely for Monday through
Thursday. A large area of pressure will move in from the northwest
on Monday as a strong trough moves into the eastern CONUS.
Temperatures will be on the cool side Monday night and Tuesday
night with lows in the 40s. Height rises across the Gulf of
Mexico and Gulf States on Wednesday and Thursday suggest that any
weather systems will have difficulty penetrating into the Deep
South.

87/Grantham

&&

.AVIATION...
00Z TAF Discussion.

VFR through 06z or so and then our unsettled weather starts for a
few days. Ceilings gradually lower to MVFR and may end up IFR for
a few hours around 15z. At this time, have showers mentioned and
PROB30 for thunder through the day. Winds will be southeast
overnight and swinging around to the southwest Saturday mainly
5-10kts.

75

&&

.FIRE WEATHER...

Showers and storms will move through the area from north to
south late tonight and Saturday, with another round of showers and
storms Sunday and Sunday night. Dry conditions return by midday
Monday behind a cold front, lasting through much of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     58  76  54  72  56 /  90  70  30  60  90
Anniston    59  76  55  74  58 /  90  70  30  70  90
Birmingham  62  77  57  73  58 /  90  80  40  70  90
Tuscaloosa  65  77  59  74  58 /  70  90  40  70  90
Calera      63  77  59  74  59 /  80  80  40  70  90
Auburn      60  77  60  74  60 /  60  70  40  70  90
Montgomery  60  81  62  78  63 /  50  70  40  70  90
Troy        58  84  62  79  63 /  30  60  40  70  80

&&

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

&&

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