(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).
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 220838
SPC AC 220838
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0338 AM CDT WED MAY 22 2013
VALID 251200Z - 301200Z
...DISCUSSION...
MEDIUM RANGE MODELS GENERALLY AGREE WITH RESPECT TO THE LARGE-SCALE
PATTERN THROUGH DAY 6 /MON. 5-27/...WITH MORE SUBSTANTIAL
DIFFERENCES EMERGING THEREAFTER.
OVERALL...THE PATTERN THROUGH DAY 6 SHOULD FEATURE A SLOWLY
DEPARTING NERN U.S. TROUGH...WITH A SECOND/EVOLVING TROUGH REMAINING
OVER THE WRN HALF OF THE CONUS. AS VORTICITY MAXIMA EJECT
REPEATEDLY FROM THIS TROUGH INTO THE PLAINS -- WHERE A LARGE-SCALE
RIDGE WILL PERSIST...DIURNAL HIGH-PLAINS CONVECTION INITIATING INVOF
THE LEE TROUGH WILL LIKELY BE THE PREVAILING CONVECTIVE THREAT FOR
SEVERAL DAYS. WHILE SOME SEVERE THREAT WILL LIKELY ACCOMPANY EACH
OF THESE EJECTING FEATURES GIVEN THE LIKELIHOOD FOR AMPLE
INSTABILITY AND AT LEAST MARGINALLY SUPPORTIVE SHEAR PROFILES EACH
DAY...THE THREAT EACH DAY SHOULD REMAIN BELOW CRITERIA WHICH WOULD
SUGGEST INCLUSION OF A 30% EQUIVALENT THREAT AREA.
..GOSS.. 05/22/2013
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