SPC AC 220100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT MON SEP 21 2009
VALID 220100Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF CENTRAL/NERN TX
TO ERN OK/WRN AR...
...SYNOPSIS...
WATER VAPOR IMAGERY INDICATED AN UPPER LOW MOVING EQUATORWARD WITH
THIS SYSTEM EXPECTED TO BECOME FURTHER DETACHED/CUT-OFF FROM
STRONGER WLY FLOW ALOFT OVER CANADA. SEVERAL VORTICITY MAXIMA
LOCATED ALONG ERN EXTENT OF THIS UPPER SYSTEM WILL TRACK ENEWD
TONIGHT REACHING THE UPPER/MID MS VALLEY AND THE ARKLATEX REGION BY
12Z TUESDAY.
...SRN PLAINS TO OZARKS...
A COLD FRONT LOCATED ALONG ERN PERIPHERY OF THE UPPER LOW EXTENDED
FROM THE UPPER MS VALLEY SSWWD ALONG THE KS/MO BORDER TO N CENTRAL
AND SW TX. ALTHOUGH THERE HAVE BEEN DISCRETE STORMS THIS
AFTERNOON/EARLY EVENING AHEAD OF THE FRONT...LINEAR FORCING/DEEP
LAYER SHEAR ALIGNED ALONG THE FRONT WILL SUPPORT MORE LINE SEGMENTS
AS ADDITIONAL STORMS FORM AS THE FRONT ENCOUNTERS MODERATE
INSTABILITY THIS EVENING. COLD POOL ENHANCED LINES OF STORMS MAY
TEND TO LOCALLY RESULT IN STRONGER WIND GUSTS...PRIOR TO THE ONSET
OF STRONGER SURFACE BASED INHIBITION WHICH SHOULD SUPPORT AN
EVENTUAL DECREASE IN STORM INTENSITY/SEVERE THREAT LATER THIS
EVENING.
...SRN HIGH PLAINS...
A COLD FRONT SURGING SWD THROUGH THE SRN HIGH PLAINS WILL PROGRESS
FARTHER S THIS FORECAST PERIOD...REACHING THE U.S./MEXICO BORDER
LATE TONIGHT/EARLY TUESDAY MORNING. TSTMS THAT DEVELOPED IN THE
VICINITY OF THIS BOUNDARY OVER ERN NM/W TX WERE LOCATED WITHIN EXIT
REGION OF STRONG MID LEVEL JET MOVING INTO BASE OF THE EVOLVING
UPPER LOW WHERE FORCING FOR ASCENT SHOULD SUPPORT ADDITIONAL STORMS
THIS EVENING. EFFECTIVE BULK SHEAR WILL REMAIN STRONG ENOUGH TO
SUPPORT ORGANIZED STORMS...BUT A DECREASE IN AVAILABLE CONVECTIVE
INSTABILITY SUGGESTS THE OVERALL SEVERE WEATHER THREAT SHOULD
DIMINISH. HOWEVER...STRONG GRADIENT WINDS/HIGHER GUSTS SHOULD
PERSIST AS THE COLD FRONT SURGES SWD.
..PETERS.. 09/22/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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