(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 a 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 highly unlikely during the entire period (e.g. less than a 30% probability for a regional severe storm area across the CONUS through the entire Day 4-8 period).
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 160852
SPC AC 160852
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0352 AM CDT TUE SEP 16 2014
VALID 191200Z - 241200Z
THE ECMWF AND GFS MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH AN
UPPER-LEVEL RIDGE OVER ERN PARTS OF THE GREAT PLAINS AND MOVE THIS
FEATURE EWD INTO THE MID TO UPPER MS VALLEY ON FRIDAY/DAY 4. AT THE
SAME TIME...AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE INTO THE HIGH
PLAINS FRIDAY AFTERNOON OVER A MOIST AIRMASS. THIS WOULD SUGGEST
THUNDERSTORM DEVELOPMENT WITH SOME POSSIBLY SEVERE...MAY OCCUR IN
THE LATE AFTERNOON AND EARLY EVENING ON FRIDAY IN THE SRN AND CNTRL
PLAINS. THE UPPER-LEVEL TROUGH IS FORECAST TO MOVE ACROSS THE CNTRL
PLAINS AND UPPER MIDWEST ON SATURDAY/DAY 5. THUNDERSTORM DEVELOPMENT
WILL AGAIN BE POSSIBLE SATURDAY AFTERNOON ALONG THE TROUGH DURING
THE LATE AFTERNOON AND EARLY EVENING. ALTHOUGH THE ECMWF AND GFS
SOLUTIONS DIVERGE ON SUNDAY/DAY 6...BOTH SOLUTIONS MOVE THE
UPPER-LEVEL TROUGH EWD ACROSS THE MID MS AND LOWER OH VALLEYS.
THUNDERSTORM DEVELOPMENT WOULD BE POSSIBLE FROM THE OH VALLEY SWWD
INTO THE MID MS VALLEY AND SRN PLAINS SUNDAY AFTERNOON. ON
MONDAY/DAY 7...BOTH SOLUTIONS DRIVE A COLD FRONT SEWD INTO THE GULF
COAST STATES SUGGESTING THAT THUNDERSTORM ACTIVITY WILL BE POSSIBLE
THERE MONDAY AFTERNOON. ALTHOUGH THERE APPEARS TO BE A REASONABLE
CHANCE FOR SEVERE THUNDERSTORM DEVELOPMENT IN PARTS OF THE GREAT
PLAINS AND UPPER MIDWEST ON FRIDAY AND SATURDAY...UNCERTAINTY STILL
REMAINS CONCERNING THE AMOUNT INSTABILITY THAT WILL BE IN PLACE
REGARDING THE SEVERE THREAT.
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