Severe Storm Outlook Narrative (AC)
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ACUS48 KWNS 180832
SWOD48
SPC AC 180831

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0331 AM CDT FRI APR 18 2014

VALID 211200Z - 261200Z

...DISCUSSION...
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
PERIOD.

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.

..DARROW.. 04/18/2014



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