DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 071712
SWODY2
SPC AC 071710

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1110 AM CST MON JAN 07 2013

VALID 081200Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SCNTRL TX...

...SCNTRL TX...
AN UPPER-LEVEL LOW WILL MOVE EWD ACROSS THE NRN PART OF MEXICO ON
TUESDAY AS A WELL-DEFINED MID-LEVEL JET ROUNDS THE BASE OF THE
SYSTEM. IN RESPONSE...A LOW-LEVEL JET WILL STRENGTHEN ACROSS THE
SCNTRL TX WITH MOISTURE RETURN TAKING PLACE DURING THE DAY. MODEL
FORECASTS INCREASE SFC DEWPOINTS INTO THE 60S F IN THE LOWER TO
MIDDLE TX COASTAL PLAINS BY TUESDAY AFTERNOON AND DEVELOP MODERATE
INSTABILITY. THUNDERSTORMS MAY BE ONGOING ALONG THE NOSE OF THE
LOW-LEVEL JET ACROSS THE TX HILL COUNTRY TUESDAY MORNING CONTINUING
INTO THE AFTERNOON AS THE LOW-LEVEL JET GRADUALLY STRENGTHENS. BY
TUESDAY EVENING...THE MODELS APPEAR TO DEVELOP AN MCS ALONG THE WRN
EDGE OF THE LOW-LEVEL JET WITH THIS CLUSTER OF STORMS MOVING EWD
ACROSS SCNTRL TX DURING THE EVENING AND OVERNIGHT PERIOD.

FORECAST SOUNDINGS AT 03Z/WED ABOUT 100 STATUTE MILES SOUTH OF SAN
ANTONIO SWWD TO THE RIO GRANDE RIVER GENERALLY SHOW MLCAPE VALUES
AROUND 1000 J/KG WITH 0-6 KM SHEAR IN THE 55 TO 60 KT RANGE. THIS
COMBINATION OF SHEAR AND INSTABILITY COULD SUPPORT SUPERCELL
FORMATION ESPECIALLY IF CELLS CAN REMAIN DISCRETE WITHIN THE
DEVELOPING MCS OR IF STORMS CAN INITIATE OUT ACROSS THE WARM SECTOR.
THE MAIN ISSUE IS THE TIMING OF THE UPPER-LEVEL LOW WHICH THE MODELS
APPEAR TO BE A BIT SLOW TO MOVE TO THE EAST. AT THIS POINT...THE NAM
MOVES THE LEADING EDGE OF LARGE-SCALE ASCENT ACROSS THE RED RIVER
AROUND 06Z TUESDAY EVENING. THIS LATE OF AN APPROACH WOULD DEVELOP
THE MCS IN WEAKENING INSTABILITY KEEPING THE SEVERE THREAT MORE
ISOLATED. GIVEN THAT LOW-LEVEL SHEAR IS FORECAST TO BE QUITE STRONG
AND MID-LEVEL LAPSE RATES ARE FORECAST TO BE A BIT ON THE MARGINAL
SIDE...THE MAIN THREAT WOULD PROBABLY BE FOR A TORNADO OR WIND
DAMAGE.

..BROYLES.. 01/07/2013

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