(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 020826
SPC AC 020826
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0326 AM CDT TUE SEP 02 2014
VALID 051200Z - 101200Z
ECMWF/GFS BOTH AGREE THAT UPPER GREAT LAKES SPEED MAX WILL EJECT
ACROSS ONTARIO INTO QUEBEC DURING THE DAY4 PERIOD...WELL NORTH OF
THE INTERNATIONAL BORDER. THIS EVOLUTION WILL FORCE A SFC FRONT
INTO NY...WHILE A MUCH WEAKER BOUNDARY SHOULD TRAIL ACROSS THE OH
VALLEY. CONVECTION IS EXPECTED TO DEVELOP ALONG THIS WIND SHIFT BUT
LATEST GUIDANCE SUGGESTS THE STRONGEST DEEP LAYER SHEAR WILL LAG THE
FRONTAL ZONE SUCH THAT TSTMS THAT EVOLVE SHOULD BE MORE
MULTI-CELLULAR IN NATURE AND POSSIBLY LESS ORGANIZED. BEYOND THE
DAY4 PERIOD...MEANINGFUL INSTABILITY WILL BE DISPLACED WELL SOUTH OF
STRONGER FLOW ALOFT AND SEVERE PREDICTABILITY WILL LESSON
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