SPC AC 280551
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1251 AM CDT FRI APR 28 2006
   
   VALID 281200Z - 291200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF WCNTRL/CNTRL
   TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE SRN
   PLAINS...
   
   ...SYNOPSIS...
   A HIGHLY AMPLIFIED UPPER FLOW REGIME WILL CONTINUE ON FRI.  UPPER
   LOW NOW MOVING ACROSS THE DESERT SW WILL ACCELERATE EWD THROUGH THE
   SRN ROCKIES EARLY TODAY AS IT BEGINS TO PHASE WITH A NRN STREAM
   IMPULSE DROPPING SWD THROUGH THE PLAINS.  THE SRN DISTURBANCE AND
   ATTENDANT 60-METER/12-HR HEIGHT FALLS WILL SPREAD EWD ACROSS THE SRN
   PLAINS FRI AFTN/NIGHT.
   
   AT THE SFC...THE WARM FRONT SITUATED ACROSS SRN TX WILL REDEVELOP
   NWD THROUGH WRN/CNTRL TX BY FRI AFTN.  A LEE-TROUGH/DRYLINE WILL
   BECOME ESTABLISHED FROM THE SRN TX PNHDL SWD INTO SWRN TX BY FRI
   MID-AFTN.  MEANWHILE...A COLD FRONT...ASSOCIATED WITH THE NRN STREAM
   TROUGH...WILL MOVE SEWD ACROSS THE ERN PLAINS AND SWD THROUGH THE TX
   PNHDL THROUGH FRI NIGHT.
   
   ...SRN PLAINS...
   THERE WILL LIKELY BE WIDESPREAD CLOUDS/CONVECTION ONGOING EARLY FRI
   MORNING ACROSS PARTS OF OK AND CNTRL/ERN TX...ALONG THE NOSE OF A
   LLJ.  THIS WILL ACT TO REINFORCE THE NW-SE ORIENTED FRONT ACROSS
   CNTRL TX THROUGH FRI EVENING.
   
   LATEST MODELS SUGGEST THAT THE WARM CONVEYOR WILL BEGIN TO SHIFT EWD
   DURING THE AFTN.  THIS SHOULD ALLOW STRONG HEATING TO OCCUR ACROSS
   SWRN/WCNTRL TX NWD INTO THE ERN TX PNHDL/SWRN OK FRI AFTN. 
   CONCURRENTLY...LOW-LEVEL MOISTURE...NOW IMPROVING ACROSS DEEP S TX
   NWWD INTO THE TRANSPECOS REGION...WILL ADVECT NWWD AS THE SELY FLOW
   ACCELERATES AHEAD OF THE APPROACHING UPPER LOW.  BY PEAK
   HEATING...60S BOUNDARY LAYER DEW POINTS SHOULD EXIST ALONG/E OF THE
   DRYLINE AND SOUTH OF THE WARM FRONT.
   
   STEEPENING MID-LEVEL LAPSE RATES...OWING TO LARGE SCALE
   ASCENT/MOISTENING AND MID-LEVEL COLD ADVECTION...SPREADING EWD ATOP
   THE LOW-LEVEL THETA-E AXIS WILL ENCOURAGE TSTMS TO INITIATE ALONG
   THE DRYLINE/HIGHER TERRAIN BY MID-AFTN FROM THE ERN TX PNHDL SWD
   INTO SWRN TX.  GIVEN 70+ KTS OF VERTICAL SHEAR AND MAGNITUDE OF
   INSTABILITY...TSTMS WILL LIKELY GROW INTO SUPERCELLS WITH VERY LARGE
   HAIL...PARTICULARLY OVER WCNTRL/CNTRL TX SWD TOWARD THE RIO GRANDE. 
   BACKED LOW-LEVEL FLOW VCNTY OF THE RETREATING WARM FRONT WILL ALSO
   BE FAVORABLE FOR TORNADOES...ESPECIALLY GIVEN THE INFLUX OF A MOIST
   BOUNDARY LAYER.
   
   THE MID-LEVEL FLOW WILL GRADUALLY BACK DURING THE EVENING AS THE
   UPPER LOW MOVES EWD.  THUS...TSTMS WILL TEND TO EVOLVE INTO A LINEAR
   MCS AFTER DARK...THEN MOVE EWD ACROSS OK...CNTRL/ERN TX OVERNIGHT
   WITH ATTENDANT HAIL/HIGH WINDS.  STRONGER ACTIVITY WILL LIKELY FAVOR
   THE SRN EDGE OF THE MCS ACROSS SCNTRL TX WHERE THE BETTER QUALITY
   MOISTURE/INSTABILITY WILL RESIDE S OF THE WARM FRONT.
   
   ...NRN PLAINS...
   STEEP LOW/MID-LEVEL LAPSE RATES BENEATH THE WEAKENING NRN STREAM
   IMPULSE WILL PERSIST ACROSS THE NRN PLAINS FRI.  A NARROW AXIS OF
   BOUNDARY LAYER DEW POINTS AOA 45 DEG F BENEATH H5 TEMPERATURES
   AROUND MINUS 20 DEG C WILL BE FAVORABLE FOR SCT STRONG TSTMS. 
   THOUGH THE VERTICAL SHEAR WILL BE WEAK...MAGNITUDE OF THE LAPSE
   RATES WILL PROBABLY FOSTER LARGE HAIL PRODUCTION WITH ISOLD STRONGER
   UPDRAFTS.
   
   ..RACY/BRIGHT/CROSBIE.. 04/28/2006
   
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