(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 220853
SPC AC 220853
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0353 AM CDT FRI AUG 22 2014
VALID 251200Z - 301200Z
AS AN UPPER SHORT-WAVE TROUGH CONTINUES ITS NEWD DEPARTURE FROM THE
N CENTRAL U.S. DAY 4 /MON 8-25/...RIDGING IS PROGGED TO PREVAIL
ACROSS THE SRN AND ERN U.S. WHILE A LONGER WAVELENGTH WRN U.S.
TROUGH MOVES SLOWLY EWD. CONVECTION -- AND POSSIBLE SEVERE WEATHER
-- APPEARS LIKELY TO EVOLVE INVOF A COLD FRONT TRAILING SWWD FROM
THE UPPER GREAT LAKES TO THE CENTRAL HIGH PLAINS...AS THE SRN FRINGE
OF A BELT OF STRONGER MID-LEVEL SWLYS SHOULD RESIDE ATOP THE SURFACE
FRONTAL ZONE. SOME CONCENTRATION OF RISK MAY OCCUR INVOF THE ERN
CO/KS/NEB VICINITY...NEAR AND JUST TO THE COOL SIDE OF THE FRONT
WHERE SHEAR WOULD BE MAXIMIZED. HOWEVER...WITH THE GFS MORE
AGGRESSIVE WITH MID-LEVEL HEIGHT FALLS SPREADING INTO THE HIGH
PLAINS THAN THE ECMWF...CONFIDENCE IN A WIDESPREAD/SUBSTANTIAL
SEVERE EVENT REMAINS LIMITED -- AND THUS INSUFFICIENT FOR INCLUSION
OF A 30 PERCENT EQUIVALENT RISK AREA.
FROM DAY 5 ONWARD...DIFFERENCES AMONGST MEDIUM-RANGE MODELS BECOME
EVEN MORE SUBSTANTIAL...NOTABLY WITH RESPECT TO STRENGTH AND SPEED
OF THE WRN TROUGH /AND ASSOCIATED EFFECTS ON SURFACE PATTERN
EVOLUTION/ AS THIS FEATURE CROSSES THE ROCKIES AND SHIFTS INTO THE
CENTRAL CONUS. AS SUCH...NO HIGHLIGHTS OF ANY SEVERE RISK AREAS
WILL BE INCLUDED THROUGH THE REST OF THE PERIOD.
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