SPC AC 261942
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0242 PM CDT Sun Mar 26 2023
Valid 262000Z - 271200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF LOUISIANA...MISSISSIPPI...AND ALABAMA...
...SUMMARY...
Episodic severe thunderstorms will persist into tonight across a
broad portion of the Deep South/Southeast States. A few strong
tornadoes and very large hail may occur with the most intense
storms, particularly from central Louisiana across central/southern
portions of Mississippi and Alabama this afternoon and evening.
...20Z Update...
Two strong supercells have developed in far southeast Texas and
should maintain themselves as they move east. The low-level jet is
only around 25 knots per the LCH 18Z RAOB and the POE VWP. However,
this flow is expected to increase to around 35 knots by 22Z.
Therefore, the tornado threat is expected to increase once these
storms reach eastern Louisiana and into Mississippi. See MCD 357 for
additional information about the evolving threat in this region.
A cluster of supercells has developed farther north across
north-central Louisiana. Storm interference will likely keep the
severe threat somewhat muted, but some large hail is possible from
this activity.
Additional supercells may develop across eastern Louisiana and
central Mississippi this afternoon along and to the south of a
frontal zone in the region. These storms will pose a threat for all
severe weather hazards including tornadoes, some strong.
Ongoing supercells across southern Alabama and vicinity are expected
to continue through the afternoon and into the evening with mostly a
large hail threat. See MCD 358 for additional details.
A few damaging wind gusts or a brief tornado remain possible across
Northeast Illinois/northern Indiana. See MCD 356 for additional
information.
..Bentley.. 03/26/2023
.PREV DISCUSSION... /ISSUED 1133 AM CDT Sun Mar 26 2023/
...Deep South/Southeast...
Some severe potential, mostly in the form of hail/wind, may continue
early this afternoon across the South Carolina Piedmont/southern
North Carolina. This environment also remains conditionally
favorable for a few severe storms to the west across southeast
Mississippi, south-central Alabama, into west-central Georgia near
the effective front. This sub-regional corridor may be experiencing
a bout of shortwave ridging, but that at the same time, the boundary
layer will continue to diurnally destabilize.
Focus then quickly turns farther west to the potential for deep
convective development along the northward-shifting boundary from
east/southeast Texas into Louisiana, which could potentially occur
relatively early, during early/mid-afternoon. See Mesoscale
Discussion 354 for more short-term details. Low-level shear/SRH will
not initially be strong but strengthen through late afternoon/early
evening as 850mb/1-2 km AGL winds increase and low-level hodographs
enlarge. Storms, including initially semi-discrete/intense
supercells, will tend to cluster/gradually grow upscale along the
boundary with hail/wind potential, but an increased concern for
tornadoes, some of which may be strong/intense (EF2+), would exist
with supercells that evolve/persist in a semi-discrete manner south
of the boundary and move into and/or develop across
south-central/southeast Mississippi, and eventually
southwest/southern Alabama this evening as 850mb/1-2 km AGL winds
further intensify.
...Illinois/Indiana...
Low-topped thunderstorms are expected to develop this afternoon
across eastern/northeast Illinois as a low-amplitude shortwave
trough overspreads this region. Although low-level moisture should
remain limited, enough weak instability should still develop through
the day as mid-level temperatures cool with the shortwave trough
passage. With some enhanced low/mid-level flow forecast, any
convection that can develop and be sustained may pose an isolated
damaging wind risk, and perhaps a brief tornado across
north-central/northeast Illinois.
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