[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 280553
SWODY1
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