DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 071716
SWODY2
SPC AC 071713

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1113 AM CST SAT FEB 07 2009

VALID 081200Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF FAR SE NM AND
WEST TX...

...SRN AND CNTRL HIGH PLAINS...
AN UPPER-LEVEL LOW CENTERED OVER SRN CA TONIGHT IS FORECAST TO OPEN
AND DRIFT ENEWD ACROSS THE DESERT SOUTHWEST SUNDAY. THE NRN
EXTENSION OF A 75 TO 90 KT MID-LEVEL JET IN THE BASE OF THE TROUGH
IS FORECAST TO MOVE ACROSS NEW MEXICO INTO WEST TX BY LATE
AFTERNOON. LARGE-SCALE ASCENT AHEAD OF THE UPPER-LEVEL TROUGH WILL
INCREASE SUNDAY ACROSS THE HIGH PLAINS WHICH COMBINED WITH FOCUSED
LOW-LEVEL CONVERGENCE NEAR A SFC LOW SHOULD RESULT IN A LINE OF
CONVECTION INITIATING LATE SUNDAY AFTERNOON ACROSS ERN NEW MEXICO
EXPANDING EWD INTO THE TX PANHANDLE DURING THE EVENING.

AS THE SYSTEM APPROACHES THE SRN HIGH PLAINS....A 40 TO 50 KT
LOW-LEVEL JET WILL ORGANIZE HELPING TO TRANSPORT MOISTURE NWD ACROSS
MUCH OF THE SRN PLAINS SUNDAY. SFC DEWPOINTS APPEAR LIKELY TO REACH
THE UPPER 40S TO LOWER 50S F FROM THE LOW-ROLLING PLAINS OF WCNTRL
TX EXTENDING WWD ONTO THE CAPROCK ACROSS MUCH OF WEST TX. THIS
SHOULD ALLOW INSTABILITY TO DEVELOP ON THE CAPROCK BY LATE AFTERNOON
WHERE SOME MODEL FORECASTS SHOW 500 TO 750 J/KG OF SBCAPE BY 00Z
MONDAY. AS CONVECTION INITIATES ALONG THE INSTABILITY AXIS LATE
SUNDAY AFTERNOON OR EARLY SUNDAY EVENING...STRONG VERTICAL SHEAR
EVIDENT ON FORECAST SOUNDINGS AND COLD AIR ALOFT /500 MB TEMPS OF
-16 TO -18C/ SHOULD BE SUFFICIENT FOR A HAIL THREAT. THE HAIL THREAT
COULD EXTEND AS FAR NORTH AS ERN CO AND WRN KS WHERE STRONG
LARGE-SCALE ASCENT AND ADEQUATE VERTICAL SHEAR WILL EXIST.
HOWEVER...THE GREATER THREAT APPEARS LIKELY TO EXIST FROM AMARILLO
SWD TO NEAR MIDLAND WHERE SFC DEWPOINTS SHOULD BE A BIT HIGHER
RESULTING IN STRONGER INSTABILITY.

CONCERNING THE TIMING OF THE SYSTEM...MODEL FORECASTS HAVE BEEN
GRADUALLY SLOWING THE APPROACH OF THE UPPER-LEVEL TROUGH WITH EACH
RUN AND THIS COULD BE PROBLEMATIC CONCERNING THE MAGNITUDE OF THE
SEVERE THREAT. IF CONVECTIVE DEVELOPMENT IS DELAYED ACROSS WEST TX
UNTIL LATER IN THE EVENING WHEN INSTABILITY WILL BE DECREASING...THE
THE SEVERE THREAT COULD REMAIN MORE ISOLATED THAN CURRENTLY
FORECAST.

..BROYLES.. 02/07/2009

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