Thursday, April 16, 2009

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 160540
SWODY2
SPC AC 160537

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1237 AM CDT THU APR 16 2009

VALID 171200Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL/SRN HIGH
PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CNTRL/SCNTRL
TX...

...CNTRL HIGH PLAINS TO SCNTRL TX...

COMPLEXITIES...REGARDING CONVECTION...WILL BEGIN TO INCREASE
EXPONENTIALLY DURING THE DAY2 PERIOD AS SLOW MOVING UPPER LOW
MIGRATES ACROSS THE CNTRL/SRN ROCKIES INTO THE PLAINS. LATEST
GUIDANCE SUGGESTS DAY1 WILL BE CONVECTIVELY ACTIVE WELL INTO THE
OVERNIGHT HOURS...WITH SIGNIFICANT THUNDERSTORM ACTIVITY EXPECTED TO
BE ONGOING AT THE BEGINNING OF THE DAY2 PERIOD FROM THE EDWARDS
PLATEAU OF TX...NWD INTO WRN OK...ARCING NWWD INTO WRN KS. THIS
EARLY MORNING ACTIVITY WILL LIKELY BE ENHANCED BY STRONG LLJ THAT
WILL GRADUALLY SHIFT EAST INTO THE ARKLATEX LATER IN THE DAY.
ALTHOUGH EARLY MORNING COMPLEX MAY EXHIBIT ORGANIZED SQUALL LINE
STRUCTURE...IT/S NOT ENTIRELY CLEAR HOW SEVERE THIS CONVECTION WILL
BE AFTER SUNRISE. OF GREATER CONCERN WILL BE CONVECTIVE
POSSIBILITIES WITHIN DESTABILIZING ZONE ACROSS PORTIONS OF CNTRL
TX...AND PERHAPS IMMEDIATELY AHEAD OF THE UPPER LOW OVER THE HIGH
PLAINS. FORECAST MODELS DIFFER A BIT IN THE PROGRESSION OF SQUALL
LINE ACROSS TX/OK WITH THE GFS MAINTAINING CONSIDERABLE INTENSITY
WITH THIS COMPLEX INTO THE ARKLATEX REGION. AT SOME POINT THE
SQUALL LINE SHOULD OUTRUN ITS UPPER SUPPORT AND WEAKEN. LATEST
THINKING IS GREATER INSTABILITY WILL HOLD ACROSS CNTRL/SCNTRL TX
WHERE A SURGE OF MARITIME TROPICAL AIR SHOULD BE IN PLACE. THIS MAY
BE WHERE RENEWED THUNDERSTORMS COULD DEVELOP AS BOUNDARY LAYER WARMS
ALONG SRN FRINGE OF STRONGER MID LEVEL FLOW. AT ANY RATE...FORECAST
SOUNDINGS FAVOR STORM ROTATION...ESPECIALLY IF MORE DISCRETE
UPDRAFTS CAN DEVELOP LATER IN THE DAY. LARGE HAIL...DAMAGING WINDS
AND PERHAPS AN ISOLATED TORNADO CAN BE EXPECTED.

FARTHER NW...DESPITE MARGINAL LOW LEVEL MOISTURE...STRONG
THUNDERSTORMS MAY DEVELOP IN A NARROW CORRIDOR ALONG THE NRN-ERN
SEMICIRCLE OF UPPER LOW FROM SERN CO INTO EXTREME WRN OK BY
EARLY-MID AFTERNOON. VERY COLD MID LEVEL TEMPERATURES...H5 FROM
-20C TO -26C...WILL OVERSPREAD THE SRN HIGH PLAINS BENEATH THE UPPER
LOW. THUNDERSTORMS SHOULD EASILY DEVELOP ALONG LOW LEVEL
CONVERGENCE ZONE WHERE STRONG HEATING WILL REMOVE INHIBITION
QUICKLY. SHEAR PROFILES SUGGEST SUPERCELLS ARE POSSIBLE. PRIMARY
SEVERE THREAT WILL BE LARGE HAIL...BUT AN ISOLATED TORNADO CAN NOT
BE RULED OUT.

..DARROW.. 04/16/2009

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