SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Wed Mar 30 2022
Valid 302000Z - 311200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
FAR EASTERN ARKANSAS...EASTERN LOUISIANA...MISSISSIPPI...WESTERN
TENNESSEE...ALABAMA...AND THE WESTERN FLORIDA PANHANDLE...
...SUMMARY...
A regional outbreak of severe thunderstorms is still expected from
the Lower Mississippi Valley into parts of the Ohio and Tennessee
Valleys today, and over portions of the central Gulf Coast states
through tonight. The greatest concerns are tornadoes (some strong,
EF2+) and widespread damaging wind gusts (some to hurricane force).
...20Z Update...
An expansive QLCS has recently strengthened across eastern LA/AR as
it encounters greater low-level moisture and sufficient
boundary-layer instability to support surface-based storms. Recent
VWPs from KJAN/KNQA show rapidly strengthening winds with height
from the surface through mid levels, with over 50 kt of 0-3 km shear
present. An 18Z observed sounding from JAN likewise shows plentiful
low-level shear, and substantial erosion of the dry/stable layer
aloft that was present on the 12Z sounding. Current expectations are
for this QLCS to continue posing a threat for widespread damaging
winds given the strength of the low-level flow, and for multiple
embedded tornadoes. Severe probabilities have been trimmed behind
the line, as the severe threat will end once it passes any specific
location. For more information on the near-term severe threat across
the lower MS Valley, see Mesoscale Discussion 357.
Farther north into the mid MS and OH Valleys, ongoing showers and
cloud cover are hampering instability. Even so, potential exists for
the northern portion of the line to strengthen this afternoon and
evening as it moves across these regions. Damaging winds will likely
be the main threat, but a couple tornadoes also appear possible. The
Slight Risk was nudged northward across southern/central IL to
account for this possibility.
Otherwise, the threat for damaging winds and tornadoes will likely
continue this evening through early Thursday morning across much of
AL and the western FL Panhandle as the line moves eastward.
Low-level shear is expected to remain quite strong across this
region, and rich low-level moisture will be present as well. If the
line transitions into a broken/more semi-discrete mode as some
high-resolution guidance suggests, then a threat for strong
tornadoes may be realized, mainly across parts of southern/central
AL and the FL Panhandle overnight.
..Gleason.. 03/30/2022
.PREV DISCUSSION... /ISSUED 1056 AM CDT Wed Mar 30 2022/
...Lower OH/MS Valleys...
Morning water vapor imagery shows a progressive shortwave trough
rotating across TX/OK. This trough will become negatively-tilted
this afternoon and evening as an associated 90+ kt mid-level jet
moves into the lower MS Valley. The result will be rapid
intensification of thunderstorms over AR/LA that spread rapidly
eastward into portions of IL/KY/TN/MS later today. Low-level wind
fields are also expected to intensify rapidly ahead of the line,
resulting in very favorable shear profiles for supercells and/or
bow/lewp structures along the squall line. Widespread damaging
winds are possible across these areas, with the risk of several
tornadoes (some strong) as well.
As the storms move eastward into central KY/middle TN they will
track into a progressively more unfavorable thermodynamic
environment. This should result in a slow weakening of the damaging
wind threat along the line. However, at least some risk of damaging
winds may persist as far east as eastern KY/TN tonight.
...Southern MS/Southwest AL/Western FL Panhandle...
The aforementioned squall line will track eastward across MS/LA and
into AL by early evening, with a continued risk of widespread
damaging winds. Convective intensity may decrease during the
evening across northern AL, but greater low-level moisture farther
south should allow the storms to remain potentially severe through
much of the night. Meanwhile, low-level shear profiles will remain
quite strong and capable of tornadoes and damaging wind gusts in the
strongest cells.
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