SPC AC 160548
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1248 AM CDT THU APR 16 2009
VALID 161200Z - 171200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF THE SRN THROUGH
CNTRL HIGH PLAINS...
...SYNOPSIS...
CLOSED UPPER LOW NEAR THE FOUR CORNERS AREA WILL MOVE SLOWLY EAST...
REACHING THE CNTRL AND SRN HIGH PLAINS THURSDAY NIGHT. A DRYLINE/LEE
TROUGH WILL PERSIST OVER THE HIGH PLAINS IN ADVANCE OF THIS FEATURE.
THE DRYLINE WILL MIX ACROSS WRN TX DURING THE DAY THEN RETREAT WWD
DURING THE EVENING BEFORE IT IS OVERTAKEN BY A PACIFIC FRONT.
...CNTRL AND SRN HIGH PLAINS...
RECENT OBSERVATIONS INDICATE THE RICHER BOUNDARY LAYER MOISTURE WITH
DEWPOINTS IN THE LOW 60S IS CONFINED TO SRN TX. ELY LOW LEVEL
TRAJECTORIES RESULTING FROM THE CIRCULATION AROUND CP HIGH PRESSURE
ANCHORED OVER THE ERN U.S. WILL LIMIT NWD EXTENT OF QUALITY MOISTURE
RETURN WITH 60S LIKELY REMAINING ACROSS SOUTH OR SCNTRL TX. MODELS
INDICATE AN INCREASE IN ELEVATED/MID LEVEL CONVECTION WILL DEVELOP
EARLY THURSDAY OVER PORTIONS OF THE SRN PLAINS AS IMPULSE CURRENTLY
MOVING THROUGH NRN MEXICO CONTINUES ENEWD. THIS ACTIVITY MAY BE
CAPABLE OF PRODUCING MARGINALLY SEVERE HAIL. IN WAKE OF THE MORNING
CONVECTION...ANY LOW CLOUDS WILL LIKELY MIX OUT FROM WRN TX THROUGH
THE CNTRL HIGH PLAINS. DIABATIC HEATING BENEATH STEEP MID LEVEL
LAPSE RATES WILL CONTRIBUTE TO DESTABILIZATION IN THIS REGION WITH
AN AXIS OF MLCAPE RANGING FROM AROUND 1500 J/KG OVER THE TRANSPECOS
REGION OF WRN TX TO 500 J/KG FARTHER NORTH INTO ERN CO WHERE
MOISTURE WILL BE MORE LIMITED. SURFACE BASED THUNDERSTORMS WILL
BECOME INCREASINGLY PROBABLE IN THIS REGION BY MID-LATE AFTERNOON AS
THE ATMOSPHERE DESTABILIZES AND CAP WEAKENS.
THE LOW LEVEL JET IS FORECAST TO WEAKEN DURING THE DAY AND LOW LEVEL
HODOGRAPHS WILL INITIALLY NOT BE PARTICULARLY LARGE THURSDAY
AFTERNOON OVER MUCH OF THE HIGH PLAINS. AN EXCEPTION MAY BE OVER
PARTS OF ERN CO WHERE STRONGER BACKED FLOW WILL PERSIST NE OF WEAK
SURFACE LOW. BULK SHEAR WILL FAVOR SUPERCELL MODES WITH STORMS THAT
DEVELOP. LARGE HAIL AND ISOLATED DAMAGING WIND WILL BE THE PRIMARY
THREATS. TORNADO THREAT WILL INITIALLY NOT BE PARTICULARLY HIGH
OWING TO MORE LIMITED HODOGRAPH SIZE AND FAIRLY LARGE
TEMPERATURE/DEWPOINT SPREADS. HOWEVER...A WINDOW OF OPPORTUNITY FOR
ISOLATED TORNADOES MAY DEVELOP BY EARLY EVENING AS THE LOW LEVEL JET
STRENGTHENS AND THE BOUNDARY LAYER BEGINS TO COOLS...RESULTING IN
LOWER SPREADS.
THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE...AND STORMS WILL
LIKELY GROW UPSCALE INTO AN MCS LATER IN THE EVENING/OVERNIGHT AS
THE PACIFIC FRONT AND LEADING EDGE OF COOLER MID-LEVEL TEMPERATURES
AND ASCENT ACCOMPANYING THE UPPER TROUGH OVERTAKES THE RETREATING
DRYLINE. THREAT FOR MAINLY LARGE HAIL AND ISOLATED DAMAGING WIND
WILL LIKELY CONTINUE INTO THE OVERNIGHT.
..DIAL/SMITH.. 04/16/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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