(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 180831
SPC AC 180831
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0331 AM CDT FRI APR 18 2014
VALID 211200Z - 261200Z
EARLY IN THE MEDIUM-RANGE PERIOD BOTH THE GFS AND ECMWF ARE IN
GENERAL AGREEMENT REGARDING THE MOVEMENT OF LOW-LATITUDE SHORT-WAVE
TROUGH AS IT SHIFTS EAST OF THE SRN PLAINS INTO THE LOWER MS VALLEY.
25-35KT NW H5 FLOW ON BACK SIDE-BASE OF THIS FEATURE WILL ENHANCE
DEEP-LAYER SHEAR COINCIDENT WITH MODEST INSTABILITY. STRONG HEATING
WILL LIKELY DEVELOP ACROSS THE HILL COUNTRY OF TX AND DAYTIME
HEATING COULD PROVE INSTRUMENTAL IN A FEW SUPERCELLS IN THE WAKE OF
SHORT WAVE. GIVEN THAT THIS ACTIVITY WOULD EVOLVE WITHIN A BROADER
ZONE OF LESS THAN FAVORABLE LARGE-SCALE ASCENT...COVERAGE SHOULD BE
INADEQUATE TO WARRANT 30 PERCENT SEVERE PROBS DURING THE DAY4
LATER IN THE WEEK MODEL SOLUTIONS BEGIN TO DIVERGE A BIT AS
LARGE-SCALE PATTERN CHANGES. ECMWF IS CONSIDERABLY FASTER THAN THE
GFS ALLOWING A STRONG SHORT-WAVE TROUGH TO TRANSLATE INTO THE
ROCKIES BY WEDNESDAY. DIFLUENT FLOW ALOFT AND STRENGTHENING SHEAR
PROFILES WOULD PROVE POTENTIALLY FAVORABLE FOR A PLAINS SEVERE
EVENT. HOWEVER...GFS DOES NOT EJECT THIS FEATURE UNTIL LATER
THURSDAY. EITHER OF THESE SOLUTIONS COULD GENERATE A POTENTIALLY
SIGNIFICANT SEVERE EVENT BUT TIMING DIFFERENCES PREVENT DELINEATING
AN ORGANIZED SEVERE THREAT THIS PERIOD.
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