(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 210900
SPC AC 210900
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CDT FRI OCT 21 2016
VALID 241200Z - 291200Z
A PROGRESSIVE SHORTWAVE TROUGH EXPECTED TO MOVE THROUGH THE
SOUTHWEST STATES ON MONDAY...RESULTING IN SHOWERS/THUNDERSTORMS IN
THAT REGION...WILL PROCEED DOWNSTREAM FROM THE FOUR CORNERS STATES
INTO THE CENTRAL PLAINS...AND PERHAPS AFFECTING OK. TIMING/
AMPLIFICATION DIFFERENCES EXIST BETWEEN THE 00Z ECMWF/GFS WITH THE
APPROACHING MIDLEVEL TROUGH AND SUBSEQUENT EASTWARD ADVANCEMENT OF A
SURFACE TROUGH ACROSS THE CENTRAL/SOUTHERN PLAINS. DESPITE THESE
DIFFERENCES...GENERALLY MARGINAL INSTABILITY EXPECTED ALONG THE
SURFACE WIND SHIFT SHOULD LIMIT COVERAGE OF STRONG TO SEVERE STORMS.
00Z ECMWF/GFS TEND TO AGREE WITH THE EAST-NORTHEAST TRACK OF THE DAY
5 SHORTWAVE TROUGH THROUGH THE MID/UPPER MS VALLEY INTO THE OH
VALLEY/GREAT LAKES REGION...WITH A COLD FRONT PASSAGE ACROSS IA/MO
AND IL. HOWEVER...WEAK DESTABILIZATION IS EXPECTED TO LIMIT THE
SEVERE-WEATHER THREAT WEDNESDAY AFTERNOON/EVENING.
...BEYOND DAY 6...
THE PRESENCE OF A MIDLEVEL ANTICYCLONE CENTERED FROM THE SOUTHWEST
STATES TO THE SOUTHERN PLAINS LATE NEXT WEEK...MEAGER INSTABILITY
AND MODEL UNCERTAINTY IN THE UPPER FLOW PATTERN RESULT IN THE
POTENTIAL BEING TOO LOW FOR ORGANIZED SEVERE STORMS.
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