(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 200845
SPC AC 200845
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Fri Apr 20 2018
Valid 231200Z - 281200Z
Upper low over the Southeast states at the beginning of the extended
period (12Z D4/Monday) is expected to slowly drift
northward/northwestward on D4/Monday and D5/Tuesday before
eventually becoming absorbed into a shortwave trough progressing
eastward/southeastward from the Plains into the eastern CONUS on
D6/Wednesday and D7/Thursday. More northerly trajectory of this
shortwave trough coupled with only modest moisture return should
mitigate the severe-weather potential through next week.
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