(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 15%, 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 unlikely (i.e., less than 15%) for the forecast day.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 310839
SPC AC 310839
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0339 AM CDT TUE MAR 31 2015
VALID 031200Z - 081200Z
DESPITE SOME DIFFERENCES IN TIMING...GFS AND ECMWF GENERALLY AGREE
THAT A COLD FRONT WILL CONTINUE MOVING EWD TOWARD THE ATLANTIC COAST
AND SWD TOWARD THE GULF COAST DAY 4 /FRI 4-3/...AS THE PARENT UPPER
TOUGH ADVANCES INTO THE ERN U.S. WITH TIME. WITH A FAVORABLY MOIST
AIRMASS AHEAD OF THE FRONT AS FAR ENEWD AS THE TN VALLEY/CENTRAL
GULF COAST REGION...DIURNAL HEATING WILL SUPPORT MODERATE
DESTABILIZATION -- AND ASSOCIATED/SCATTERED AFTERNOON STORM
DEVELOPMENT INVOF THE COLD FRONT.
WITH STRONG WLY FLOW ALOFT ATOP THE AREA...SHEAR WILL SUPPORT
ORGANIZED/LOCALLY SEVERE STORMS...THOUGH VEERED LOW-LEVEL FLOW
SUGGESTS THAT PRIMARY SEVERE RISK WILL LIKELY BE HAIL AND LOCALLY
DAMAGING WINDS. A MORE ISOLATED/LOWER SEVERE RISK MAY EXTEND ENEWD
TOWARD THE APPALACHIANS /THOUGH WEAKER INSTABILITY SHOULD PROVE TO
BE A LIMITING FACTOR/ AS WELL AS WSWWD INTO TX /THOUGH CAPPING
SHOULD LIMIT STORM COVERAGE/.
WITH THE FRONT PROGGED TO MOVE OFF THE ATLANTIC AND GULF COASTS AND
A DRY/STABLE CONTINENTAL AIRMASS TO SPREAD ACROSS THE ERN 2/3 OF THE
CONUS...SEVERE RISK WILL LIKELY REMAIN LOW THROUGH THE MIDDLE OF THE
PERIOD -- ROUGHLY DAYS 5-7. TOWARD THE END OF THE PERIOD
HOWEVER...UPPER TROUGHING IN THE WEST AND SOME RETURN OF LOW-LEVEL
MOISTURE INTO THE CENTRAL U.S. AHEAD OF LEE TROUGHING/CYCLOGENESIS
SUGGESTS A GRADUAL INCREASE IN CONVECTIVE RISK TOWARD -- AND AFTER
-- THE END OF THE PERIOD.
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