Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS03 KWNS 210723
SWODY3
SPC AC 210722

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0222 AM CDT SUN SEP 21 2014

VALID 231200Z - 241200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE ON
TUESDAY...PARTICULARLY ACROSS PARTS OF THE CENTRAL PLAINS...UPPER
MIDWEST...AND SOUTHERN ROCKIES.

...SYNOPSIS...
A SPLIT UPPER-FLOW PATTERN WILL UNDERGO A DEGREE OF AMPLIFICATION ON
TUESDAY AS RELATIVELY WEAK WESTERLIES REMAIN OVER MOST OF THE CONUS.
A REMNANT UPPER LOW/SHORTWAVE TROUGH ANTICIPATED TO BE OVER THE
NORTH-CENTRAL HIGH PLAINS EARLY TUESDAY SHOULD CONTINUE TO MOVE
NORTHEASTWARD AND WEAKEN OVER THE DAKOTAS/UPPER MIDWEST. ASSOCIATED
WARM ADVECTION WILL CONTRIBUTE TO THUNDERSTORMS ACROSS THE CENTRAL
PLAINS/UPPER MIDWEST BEGINNING EARLY IN THE PERIOD...WHILE OTHER
THUNDERSTORMS /SOME POSSIBLY STRONG/ DEVELOP LATER IN THE DAY IN
VICINITY OF A CENTRAL PLAINS LEE TROUGH. ELSEWHERE...NON-SEVERE
THUNDERSTORMS WILL ALSO BE POSSIBLE ALONG/SOUTH OF A REMNANT FRONTAL
ZONE ACROSS FL AND SOUTH TX.

...CENTRAL PLAINS...
AFOREMENTIONED UPPER LOW/SHORTWAVE TROUGH SHOULD GENERALLY SPREAD
NORTHEASTWARD AWAY FROM THE REGION DURING THE DAY...WITH RELATIVELY
WEAK CYCLONIC WESTERLIES COINCIDENT WITH A LEE-SIDE SURFACE TROUGH.
WHILE OVERALL FORCING WILL BE RELATIVELY WEAK...SUFFICIENT
HEATING/CONVERGENCE NEAR THE LEE TROUGH COULD CONTRIBUTE TO ISOLATED
SURFACE-BASED THUNDERSTORM DEVELOPMENT TUESDAY AFTERNOON/EARLY
EVENING...POTENTIALLY INCLUDING AREAS SUCH AS WESTERN KS/SOUTHWEST
NEB AND THE TX/OK PANHANDLES. CURRENT THINKING IS THAT MLCAPE COULD
REACH 500-1000 J/KG BY PEAK HEATING IN VICINITY OF THE
TROUGH...ALTHOUGH EFFECTIVE SHEAR SHOULD GENERALLY BE 30 KT OR LESS.
WHILE A WEAK FORCING/VERTICAL SHEAR REGIME CURRENTLY PRECLUDES A
SEVERE RISK...LOW SEVERE PROBABILITIES /RELATED TO HAIL POTENTIAL/
COULD BE WARRANTED IN SUBSEQUENT OUTLOOKS.

..GUYER.. 09/21/2014



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