Saturday, September 19, 2009

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 190632
SWODY3
SPC AC 190629

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0129 AM CDT SAT SEP 19 2009

VALID 211200Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE CNTRL AND
SRN PLAINS...

...SYNOPSIS...

INTENSE SHORT WAVE TROUGH INITIALLY OVER WY WILL BECOME DETACHED
FROM THE PRIMARY BELT OF POLAR WESTERLIES...FORMING A CUT-OFF
CIRCULATION OVER THE CNTRL/SRN ROCKIES INTO ADJACENT HIGH PLAINS.
IN THE LOW-LEVELS...COLD FRONT WILL INTENSIFY WHILE SURGING SWD
THROUGH THE CNTRL INTO SRN HIGH PLAINS. NERN EXTENSION OF FRONT
WILL MOVE MORE SLOWLY EWD THROUGH THE MID/LOWER MO VALLEY TOWARD MID
MS VALLEY.

...LOWER MO RIVER VALLEY INTO THE SRN PLAINS...

A MOIST...PRE-FRONTAL AIR MASS /I.E. DEWPOINTS IN THE 60S/ WILL BE
OVERSPREAD BY EML PRECEDING MIDLEVEL TROUGH...CONTRIBUTING TO A
MODERATELY UNSTABLE AIR MASS BY AFTERNOON FROM LOWER ELEVATIONS OF
THE CNTRL PLAINS THROUGH THE RED RIVER VALLEY. TSTMS MAY BE ONGOING
OR DEVELOP EARLY IN THE PERIOD ALONG FRONT OVER ERN KS/WRN MO WHERE
CAP WILL BE WEAKER. SUBSEQUENT STORM FORMATION IS ANTICIPATED
THROUGH THE DAY SWWD ALONG FRONTAL ZONE AS STRONGER FORCING FOR
ASCENT SPREADS SEWD FROM THE CNTRL ROCKIES. MODEL GUIDANCE SUGGESTS
THAT THE STRONGER DEEP-LAYER WIND FIELDS WILL LAG SURFACE FRONT TO
THE NW. HOWEVER...MODEST VERTICAL SHEAR COUPLED WITH THE STEEP
LAPSE RATES AND MODERATE CONVECTIVE INSTABILITY WILL BE SUPPORTIVE
OF ORGANIZED TSTM CLUSTERS/LINE SEGMENTS CAPABLE OF MAINLY DAMAGING
WINDS AND HAIL.

..MEAD.. 09/19/2009

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