DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201632
SWODY1
SPC AC 201630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1030 AM CST WED FEB 20 2013

VALID 201630Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF TX AND OK...

MORNING WATER VAPOR LOOPS SHOW A POWERFUL AND PROGRESSIVE UPPER LOW
OVER SOUTHERN CA...WITH A 90-110 KT MID LEVEL JET NOSING INTO THE
SOUTHWEST STATES. THIS SYSTEM WILL ROTATE ACROSS AZ/NM TONIGHT AND
INTO THE SOUTHERN HIGH PLAINS BY MORNING. SOUTHERLY LOW LEVEL WINDS
AHEAD OF THE SYSTEM OVER THE PLAINS WILL RESULT IN SIGNIFICANT
WARM/MOIST ADVECTION ACROSS PARTS OF TX/OK. HOWEVER...LIMITED DEEP
LIFT AND A CAPPING INVERSION WILL LIKELY SUPPRESS SUBSTANTIAL
CONVECTION UNTIL AFTER DARK.

LATER TONIGHT...THUNDERSTORMS ARE EXPECTED TO INTENSIFY OVER WEST TX
AS THE UPPER SYSTEM APPROACHES. THESE STORMS WILL LIKELY SPREAD
EASTWARD ACROSS WESTERN NORTH TX AND SOUTHWEST OK WHERE FORECAST
SOUNDINGS SHOW SUFFICIENT ELEVATED CAPE FOR ROBUST UPDRAFTS.
VERTICAL SHEAR THROUGH THE CLOUD-BEARING LAYER AND STEEPENING LAPSE
RATES WILL PROMOTE A RISK OF HAIL IN THE STRONGER STORMS OVERNIGHT.

LARGE SCALE FORCING WILL WEAKEN WITH SOUTHERLY EXTENT OVER TX.
HOWEVER...THE SURFACE BOUNDARY WILL LIE ALONG AN AXIS ROUGHLY FROM
ABI TO SOUTH OF DAL BY THU MORNING. THE POTENTIAL FOR CONVECTIVE
DEVELOPMENT DOES NOT APPEAR TO BE PARTICULARLY HIGH ALONG/SOUTH OF
THIS AXIS...BUT SURFACE-BASED INSTABILITY AND LOW LEVEL SHEAR WOULD
PROVIDE A CONDITIONAL RISK OF DAMAGING WINDS OR A BRIEF TORNADO IF A
THUNDERSTORM CAN BECOME ESTABLISHED.

..HART/MOSIER.. 02/20/2013

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