DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 081623
SWODY1
SPC AC 081620

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1020 AM CST SUN FEB 08 2009

VALID 081630Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SOUTHERN
PLAINS...

LATEST WATER VAPOR IMAGERY SHOWS A PROGRESSIVE UPPER LOW OVER THE
SOUTHWEST U.S. WITH A STRONG SHORTWAVE TROUGH ROTATING THROUGH BASE
OF LOW INTO NORTHWEST MEXICO. AS THE UPPER LOW SHIFTS EASTWARD INTO
NEW MEXICO LATER TONIGHT...THE SHORTWAVE TROUGH WILL BECOME
NEGATIVELY TILTED AND SURGE NORTHEASTWARD ACROSS THE TX PANHANDLE
AND INTO OK. MEANWHILE...RAPID SURFACE CYCLOGENESIS OVER WEST KS
WILL RESULT IN VERY STRONG SOUTHERLY LOW LEVEL WINDS AFTER DARK OVER
TX/OK. ALL OF THESE FACTORS WILL CREATE A FAVORABLE KINEMATIC
ENVIRONMENT FOR A FAST-MOVING SQUALL LINE WITH A RISK OF DAMAGING
WINDS TONIGHT.

THE PRIMARY FORECAST CONCERN INVOLVES THE MARGINAL NATURE OF LOW
LEVEL MOISTURE AND INSTABILITY. 12Z OBSERVED SOUNDINGS SHOW A
PRONOUNCED CAPPING INVERSION WHICH WILL HELP MAINTAIN LOW CLOUDS
THROUGH THE DAY...AND WILL SUPPRESS CONVECTION UNTIL PRIMARY UPPER
FORCING ARRIVES. A NARROW AXIS OF HEATING WILL BE POSSIBLE OVER
EASTERN NM WHERE STORMS ARE LIKELY TO BEGIN 22-00Z. THIS AREA WILL
SEE THE GREATEST POTENTIAL FOR HAIL DUE TO STEEPER LOW/MID LEVEL
LAPSE RATES.

BACKED MID LEVEL WINDS AHEAD OF TROUGH WILL LIKELY RESULT IN A QUICK
EVOLUTION TO A SQUALL LINE BY 00Z ALONG THE NM/TX BORDER...WITH
ACTIVITY RACING EAST-NORTHEASTWARD INTO NORTHWEST TX AND WESTERN OK
THROUGH THE NIGHT. INSTABILITY WILL BE INCREASINGLY LIMITED WITH
EASTWARD EXTENT. HOWEVER...POTENT UPPER FORCING /150+ M 12H HEIGHT
FALLS AT 500 MB/ AND STRENGTH OF LOW LEVEL WIND FIELDS /60-70 KT AT
850 MB/ WILL MAINTAIN A RISK OF GUSTY/LOCALLY DAMAGING WINDS ALONG
THE LINE THROUGH THE NIGHT.

..HART.. 02/08/2009

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