An outbreak of severe thunderstorms is likely today into tonight, with the greatest threat expected from Louisiana through much of the Southeast and Tennessee Valley. Strong tornadoes will be most probable during the day from northeast Louisiana across Mississippi and Alabama. Later in the afternoon and evening, another round of severe storms with widespread damaging winds, large hail and tornadoes is expected across Arkansas into western Tennessee and western Kentucky by early tonight. The severe-weather threat will persist into tonight and early Monday across Georgia and the western Carolinas.
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PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0814 AM CDT SUN APR 12 2020
...Severe thunderstorms expected over parts of the Southeast U.S.
today and tonight...
* LOCATIONS...
Alabama
Much of Mississippi
Western Georgia
Northeast Louisiana
Southeast Arkansas
* HAZARDS...
Several tornadoes, a few intense
Widespread damaging winds
Scattered large hail, some baseball size
* SUMMARY...
An outbreak of severe thunderstorms is likely today into
tonight, with the greatest threat expected from Louisiana
through much of the Southeast and Tennessee Valley. Strong
tornadoes will be most probable during the day from northeast
Louisiana across Mississippi and Alabama. Later in the afternoon
and evening, another round of severe storms with widespread
damaging winds, large hail and tornadoes is expected across
Arkansas into western Tennessee and western Kentucky by early
tonight. The severe-weather threat will persist into tonight and
early Monday across Georgia and the western Carolinas.
Preparedness actions...
Review your severe weather safety procedures for the possibility
of dangerous weather today. Stay tuned to NOAA Weather Radio,
weather.gov, or other media for watches and warnings. A tornado
watch means that conditions are favorable for tornadoes to form
during the next several hours. If a tornado warning is issued for
your area, move to a place of safety, ideally in a basement or
interior room on the lowest floor of a sturdy building.
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Sun Apr 12 2020
Valid 121300Z - 131200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS TODAY INTO
TONIGHT FROM THE ARK-LA-MISS EASTWARD INTO AL AND WESTERN GA...
...SUMMARY...
An outbreak of severe thunderstorms is likely today into tonight,
with the greatest threat expected from Mississippi across Alabama
into western Georgia. Strong tornadoes, widespread damaging winds,
and large hail are all possible.
...Synopsis...
A complex forecast today with multiple scenarios possible across a
broad area from the lower MS Valley into the TN/OH Valleys and the
Southeast. A midlevel trough near the TX Big Bend this morning will
accelerate east-northeastward to the Ark-La-Miss by this evening and
the Appalachians by the end of the period, in response to continued
amplification of a large-scale trough over the north central CONUS.
At the surface, a cyclone will move across OK today and develop
eastward to AR by this evening, followed by substantial deepening as
the cyclone moves northeastward to the OH Valley/Great Lakes
overnight. A moist/unstable warm sector will surge northward across
LA/MS/AL/GA today, setting the stage for severe storms with the
ejecting shortwave trough and deepening cyclone through tonight.
Several scenarios are possible within the overall outlook area, with
substantial uncertainty related to early/ongoing convection now in
TX.
...Northeast TX to northern MS/AL and TN this afternoon...
An ongoing cluster of severe storms continues to move
east-northeastward into east central and northeast TX this morning,
in association with a lead shortwave trough. All hazards will be
possible with this cluster which will include a mixed convective
mode of supercells and bowing segments. Low-level moisture will
surge northward today across LA/MS/AL in response to the deepening
cyclone moving from OK to AR. The main question through mid
afternoon will be whether or not surface destabilization will keep
pace with the initial cluster. If warming/moistening can occur
quickly enough, the chance for surface-based storms on the southern
flank will increase. This may occur coincident with an environment
characterized by moderate buoyancy (MLCAPE of 1500-2500 J/kg), very
strong low-level shear (0-1 km SRH of 400-500 m2/s2) as the
low-level jet strengthens over LA/MS, and effective bulk shear in
excess of 70 kt. This environment will favor embedded supercells
capable of producing strong tornadoes and damaging winds. Again,
the main questions in this corridor through this afternoon will be
the degree of organization of the late morning-early afternoon
convection, and its phasing with the surface warm front.
...MS/AL/GA/Carolinas late this afternoon through tonight...
To the south of the initial storm cluster crossing northern
MS/AL/TN, a separate pre-frontal band of convection is expected to
develop by late afternoon from southern MS into western/central AL.
This convection will be well east the synoptic cold front, in an
environment with surface-based buoyancy and very strong vertical
shear. A broken band with embedded supercells appears likely to
persist well into the overnight hours, with an associated threat for
strong tornadoes and damaging winds. The pre-frontal convection
should reach the western Carolinas by 09-12z.
...Red River Valley this afternoon to the OH Valley overnight...
An arc of convection will likely form this afternoon near the
surface low in southeast OK, and within the left-exit region of the
mid-upper jet. This convection will subsequently spread eastward
and northeastward into AR through late afternoon/evening. The
northward extent of destabilization in AR/western TN this
afternoon/evening will depend largely on the intensity and extent of
the early afternoon convection moving from LA into northern MS.
Still, steep midlevel lapse rates with the ejecting midlevel wave
and strong deep-layer vertical shear will favor fast-moving
supercells and line segments capable of producing large hail and
damaging winds. Similar to AR this afternoon, the northeast extent
of the damaging wind and tornado threat into tonight will depend
largely on how widespread/organized the convection is across
northern MS/AL this afternoon/evening, and the degree of low-level
recovery in the wake of that convection.
