Severe Storm Outlook Narrative (AC)
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000
ACUS48 KWNS 210834
SWOD48
SPC AC 210833

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0333 AM CDT MON JUL 21 2014

VALID 241200Z - 291200Z

...DISCUSSION...
CONFIDENCE IS HIGH THAT THE VIGOROUS SHORTWAVE TROUGH IMPINGING ON
THE NRN HIGH PLAINS RIDGE WILL WEAKEN ACROSS THE SRN PRAIRIE
PROVINCES BY D5/FRI. THIS FEATURE SHOULD THEN TURN SE AND AID IN THE
BROADENING OF A LARGE-SCALE TROUGH OVER THE EAST BY LATE IN THE
PERIOD...WITH THE RIDGE REBUILDING ACROSS THE NRN ROCKIES.

ORGANIZED SEVERE POTENTIAL IS EVIDENT ON D4/THU ACROSS PARTS OF THE
DAKOTAS INTO PERHAPS ERN MT AS THE TROUGH IMPINGES ON THE RIDGE AND
ASSOCIATED COLD FRONT MOVES E. WITH A SURFACE ANTICYCLONE OVER THE
GREAT LAKES...THE LOW-LEVEL MOISTURE PLUME AHEAD OF THE FRONT SHOULD
BE RELATIVELY NARROW. THE ECMWF APPEARS SLOWER WITH FRONTAL TIMING
THAN THE UKMET/GFS/CMC. THESE FACTORS PRECLUDE INTRODUCTION OF
SEVERE PROBABILITIES AOA 30 PERCENT...BUT A 15 PERCENT AREA APPEARS
WARRANTED IN LATER OUTLOOKS.

LOW-END SEVERE PROBABILITIES ARE APPARENT ON A DAILY BASIS AS A BELT
OF MODERATE WLY TO NWLY MID-LEVEL FLOW BECOMES ESTABLISHED BETWEEN
THE ERN TROUGH AND WRN RIDGE. THIS SHOULD OVERLAP THE WARM/MOIST
SECTOR ACROSS PARTS OF THE MID-MO VALLEY ON D5/FRI AND THEN SEWD
OVER PARTS OF THE TN AND MID/LOWER MS/OH VALLEYS THIS WEEKEND.

..GRAMS.. 07/21/2014


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