(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 050922
SPC AC 050922
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CST Sun Dec 05 2021
Valid 081200Z - 131200Z
An upper trough should move quickly eastward across the central and
eastern CONUS on Day 4/Wednesday, with substantial low-level
moisture probably remaining confined to parts of the immediate Gulf
Coast. This should tend to limit the potential for organized severe
thunderstorms across this region. By Day 5/Thursday, modest
amplification of the mid-level westerlies may occur over portions of
the western/central CONUS. Medium-range guidance is in reasonable
agreement that modest low-level moisture will return northward
across parts of the lower MS Valley ahead of this feature, but
severe convection appears unlikely across the developing warm sector
owing to a general lack of large-scale ascent.
It appears increasingly likely that further amplification of an
upper trough over the central CONUS should occur late this week into
early next weekend, with a corresponding northward advance of rich
low-level moisture over portions of the Gulf Coast states. Depending
on the evolution of this upper trough and related surface features,
some organized severe risk may materialize across parts of the
Southeast beginning late Day 6/Friday and continuing through Day
7/Saturday. Still, a fair amount uncertainty remains regarding the
placement and evolution of the upper trough, as well as the prospect
for robust boundary-layer instability to develop inland. At this
point, including a 15% severe area appears premature, but trends in
guidance will continue to be closely monitored.
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