Severe Storm Outlook Narrative (AC)
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ACUS03 KWNS 200654
SWODY3
SPC AC 200653

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0153 AM CDT SUN APR 20 2014

VALID 221200Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
A FEW STRONG STORMS MAY FORM ACROSS THE HIGH PLAINS FROM NORTHWEST
KANSAS INTO SOUTHEAST MONTANA DURING THE AFTERNOON AND EARLY EVENING
HOURS.

...NRN/CNTRL HIGH PLAINS...

A NOTABLE CHANGE WITHIN THE LARGE-SCALE PATTERN SHOULD LEAD TO
STRENGTHENING LEE TROUGH ACROSS THE NRN AND CNTRL HIGH PLAINS
TUESDAY.  LATEST SHORT-RANGE MODEL GUIDANCE IS IN FAIRLY GOOD
AGREEMENT REGARDING THE EVOLUTION OF UPPER TROUGH AS IT MOVES INLAND
ACROSS THE INTERIOR NWRN U.S.  BY THE END OF THE PERIOD A
SUBSTANTIAL SPEED MAX WILL ROUND THE BASE OF THE PROGRESSIVE TROUGH
AND BEGIN TO EJECT NEWD ACROSS CO/WY.  WHILE THIS FEATURE WILL NOT
TIME PARTICULARLY WELL FOR HIGH PLAINS CONVECTION DURING THE
AFTERNOON HOURS...IT APPEARS SUFFICIENT LOW-LEVEL CONVERGENCE WILL
DEVELOP ALONG THE LEE TROUGH FOR AT LEAST ISOLATED TSTMS DURING PEAK
HEATING ON DAY3.

MOISTURE WILL INITIALLY BE SOMEWHAT MARGINAL ACROSS THE HIGH PLAINS
BUT STRENGTHENING LLJ SHOULD AID MODIFIED BOUNDARY LAYER MOISTURE TO
ADVECT NNWWD ACROSS WRN KS INTO SERN MT WHERE SFC DEW POINTS ARE
EXPECTED TO RISE INTO THE 40S.  STRONG HEATING ALONG THIS CORRIDOR
SHOULD PROVE INSTRUMENTAL IN CONVECTIVE INITIATION WHERE SFC
TEMPERATURES RISE INTO THE 70S...YIELDING SBCAPE VALUES OF 500-1000
J/KG.  WHILE ABSOLUTE MOISTURE CONTENT IS EXPECTED TO REMAIN
MARGINAL...STRENGTHENING WIND FIELDS WILL BECOME INCREASINGLY
FAVORABLE FOR SUSTAINED ROTATING UPDRAFTS.  FOR THIS REASON...ALONG
WITH STEEP LAPSE RATES...HAVE OPTED TO INTRODUCE 5 PERCENT SEVERE
PROBS TO ACCOUNT FOR HAIL/GUSTY WINDS WITH HIGH-BASED CONVECTION.

...ERN U.S...

WEAK POSITIVE-TILT LONG-WAVE TROUGH SHOULD MIGRATE ACROSS THE ERN
U.S. DURING THE DAY3 PERIOD.  MODEST MOISTURE AND SUFFICIENT
INSTABILITY SHOULD EXIST AHEAD OF WEAK SFC FRONT FOR ISOLATED-SCT
TSTMS WITHIN A BROAD CORRIDOR FROM THE LOWER SABINE RIVER VALLEY OF
THE UPPER TX COAST...NEWD INTO THE NRN MIDDLE ATLANTIC.
ENVIRONMENTAL SHEAR/INSTABILITY APPEAR INADEQUATE FOR ORGANIZED
SEVERE THUNDERSTORMS.

..DARROW.. 04/20/2014




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