Severe Storm Outlook Narrative (AC)
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ACUS48 KWNS 220859
SWOD48
SPC AC 220858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Fri Mar 22 2024

Valid 251200Z - 301200Z

...DISCUSSION...
A highly amplified upper trough, with multiple embedded shortwaves,
appears likely to continue progressing eastward across the
western/central CONUS early next week. One such shortwave trough
should move quickly northeastward across the Upper Midwest while
becoming increasingly displaced from the surface warm sector.
Another, southern-stream shortwave trough is forecast to advance
across northern Mexico and the southern Plains into the lower MS
Valley and Southeast from Day 4/Monday into Day 5/Tuesday. A
consensus of the latest deterministic and ensemble guidance shows a
somewhat slower ejection of the southern-stream shortwave trough,
and related placement of a surface cold front. Accordingly, greater
low-level moisture may not advance as far northward across the lower
MS Valley as previously expected. The 15% severe delineation for
Monday has been adjusted accordingly, and highlights the area where
confidence is greatest that weak, but sufficient, instability will
overlap with strong low-level and deep-layer shear. A risk of
supercells/bowing line segments and tornadoes should exist Monday
through Monday night from parts of east TX into LA/MS and vicinity,
along and south of a warm front and secondary surface low
development.

The embedded shortwave trough should move north-northeastward across
the lower MS Valley into the TN/OH Valleys on Tuesday. Greater
low-level moisture (60s surface dewpoints) will likely remain
confined to portions of the central Gulf Coast states, namely
southeastern LA into southern/central MS/AL and the FL Panhandle.
These areas will perhaps have the best potential for a continuation
of the Monday severe threat into Tuesday. But, there are concerns
that the convection will outpace the low-level moisture return. Will
defer the possible inclusion of a 15% severe area for Tuesday across
this region to a later outlook, pending greater confidence that
convection will be able to maintain its intensity and remain
surface-based. For Day 6/Wednesday and beyond, potential for a
continuation of the severe threat across parts of the southeastern
states becomes even more uncertain.

..Gleason.. 03/22/2024


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