(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.
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 220854
SPC AC 220854
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Sun May 22 2022
Valid 251200Z - 301200Z
...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
An upper-level trough is forecast to move eastward across the
southern Plains on Wednesday. Southwest mid-level flow will likely
be established ahead of the system across the lower to mid
Mississippi Valley. A moist airmass is forecast ahead of the system
from the Texas Coastal plain northeastward into the mid Mississippi
and Ohio Valleys. Thunderstorm development will be possible along
this entire corridor Wednesday afternoon. The strongest instability
is forecast to remain in the lower Mississippi Valley and central
Gulf Coast states, where there is potential for organized
convection. The most likely area for a severe threat is currently
from southeast Texas eastward across Louisiana into southwest
Mississippi, where a 15 percent contour has been added. An isolated
but marginal severe threat may also develop further north into the
and Tennessee Ohio Valleys, where instability is forecast to remain
relatively weak.
On Thursday, the upper-level trough is forecast to accelerate some,
reaching the Ohio and Tennessee Valleys during the day. By Thursday
afternoon, the instability axis is forecast to be across the
Carolinas, where there will be a potential for strong thunderstorms.
Additional thunderstorm development may take place in the weaker
instability to the north from the Mid-Atlantic into parts of the
Northeast. A severe threat could develop along parts of this
corridor, where enough instability develops and mesoscale conditions
become favorable. However, predictability on Thursday remains low
concerning any specific threat area.
On Friday, the upper-level trough is forecast to move eastward into
the Appalachians, with the cold front advancing eastward to the
Eastern Seaboard. The stronger instability is forecast to be pushed
offshore suggesting that any potential for a severe threat along or
ahead of the front should remain marginal.
...Saturday/Day 7 and Sunday/Day 8...
On Saturday and Sunday, moisture advection is forecast to take place
across the Great Plains. An upper-level trough is forecast to move
eastward across the Rockies on Saturday and into the Great Plains on
Sunday. Organized convection will be possible ahead of the
upper-level trough and near the northern edge of moderate
instability, in parts of the northern Plains Saturday afternoon. As
the trough moves eastward, the potential for organized storms should
shift eastward on Sunday into the parts of the upper Mississippi
Valley and western Great Lakes region. In spite of the current
forecasts, the model spread is large concerning timing and
instability distribution, suggesting predictability over the weekend
for any given scenario is low.
..Broyles.. 05/22/2022
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