[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 281241
SWODY1
SPC AC 281240

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0740 AM CDT FRI APR 28 2006

VALID 281300Z - 291200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF W CNTRL AND CNTRL
TX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A LARGE PART OF THE SRN
PLNS...

...SYNOPSIS...
THE MAIN BELT OF THE WLYS WILL REMAIN WELL TO THE N ACROSS CNTRL
CANADA THIS PERIOD.  PATTERN WILL...NEVERTHELESS...BECOME MORE
AMPLIFIED OVER THE LWR 48 AS SE AZ UPR LOW CONTINUES E AND PHASES
WITH NRN STREAM TROUGH NOW OVER THE NRN HI PLNS.  THE COMBINED
SYSTEMS SHOULD REACH THE CNTRL PLNS BY 12Z SATURDAY AS ASSOCIATED
60-90M HEIGHT FALL CENTER ADVANCES FROM W TX THIS AFTERNOON...AND
INTO CNTRL PARTS OF OK/KS EARLY SATURDAY.

AT LWR LEVELS..COLD FRONT NOW IN THE CNTRL HI PLNS EXPECTED TO
CONTINUE SURGING S INTO NE NM AND THE WRN/NRN OK/TX PANHANDLES
THROUGH THE AFTERNOON...BEFORE TURNING MORE SE TOWARD THE I-35
CORRIDOR TONIGHT/EARLY SATURDAY.  S OF THIS FRONT...DRY LINE/
PACIFIC COLD FRONT NOW IN NM SHOULD MIX E INTO W TX DURING THE
AFTERNOON.  AHEAD OF THIS FEATURE...DIFFUSE WARM FRONT NOW EXTENDING
FROM NEAR LBB THROUGH SJT TO VCT SHOULD REDEVELOP NE INTO CNTRL TX.

...SRN PLNS...
STRENGTHENING WARM ADVECTION/UPR LEVEL DIVERGENCE AHEAD OF AZ UPR
LOW EXPECTED TO RESULT IN INCREASING COVERAGE OF ELEVATED TSTMS
THROUGH THE DAY FROM MUCH OF KS/SRN NEB S/SE INTO CNTRL/ERN OK AND
NE TX. THIS ACTIVITY SHOULD LIMIT NWD/EWD ADVANCE OF BOUNDARY LAYER
MOISTURE RETURN ACROSS MUCH OF OK AND NE TX.

GIVEN EXISTING LOW LEVEL MOISTURE AXIS NOW EXTENDING FROM S CNTRL TX
NWWD TO NEAR MAF/LBB...AND CURRENT SATELLITE TRENDS SUGGESTING THAT
MID/UPR LEVEL CLOUDS WILL CLEAR SLOWLY SE ACROSS THE REGION THROUGH
THE DAY...EXPECT THAT SURFACE-BASED INSTABILITY AXIS BY MID
AFTERNOON WILL EXTEND FROM THE ERN TX PANHANDLE/FAR WRN OK SWD IN A
WIDENING BAND ACROSS W CNTRL TX INTO THE TX HILL COUNTRY/TX BIG
BEND.  MUCAPE LIKELY WILL RANGE FROM 1000-1500 J/KG IN THE NORTH TO
LOCALLY ABOVE 2000 J/KG NEAR THE RIO GRANDE...WHERE DEWPOINTS SHOULD
REMAIN IN THE MID TO UPR 60S.

CONVERGENCE AND HEATING SHOULD INITIATE STORMS ALONG EWD-MOVING DRY
LINE/PACIFIC COLD FRONT...AND ALONG SWD-MOVING COLD FRONT...FROM THE
SRN/ERN PANHANDLE REGION S ACROSS THE LOW ROLLING PLAINS/WRN HILL
COUNTRY BY MID TO LATE AFTERNOON.  ONE OR TWO STORMS MAY ALSO FORM
IN ZONE OF CONVERGENT UPSLOPE FLOW JUST W OF THE LWR PECOS.

PRESENCE OF NRN STREAM IMPULSE WILL KEEP A BRANCH OF THE LLJ AIMED N
TOWARD THE LWR MO VLY TODAY.  THIS WILL TEND TO WEAKEN AND VEER LOW
LVL WIND PROFILES SOMEWHAT OVER THE SRN PLNS.  NEVERTHELESS... GIVEN
STRENGTHENING MID/UPR LEVEL WINDS DOWNSTREAM FROM AZ SYSTEM /500 MB
SWLY FLOW EXPECTED TO BE AOA 70 KTS BY MID AFTERNOON ACROSS
CNTRL-SCNTRL TX/...AND DEGREE OF INSTABILITY/MOISTURE INFLOW...SETUP
LIKELY WILL FOSTER SUPERCELLS WITH VERY LARGE HAIL/ HIGH WIND AND
POSSIBLY A FEW TORNADOES...ESPECIALLY FROM E OF LBB SE INTO THE
EDWARDS PLATEAU/BIG BEND.  TORNADO POTENTIAL SHOULD BE GREATEST
INVOF ANY WARM FRONTAL SEGMENTS...WHERE SELY LOW LEVEL FLOW MAY
LOCALLY ENHANCE SRH.

AS UPR SYSTEM CONTINUES EWD...STRENGTH/LINEAR NATURE OF LARGE SCALE
FORCING...AND EXISTING WIND PROFILES...SUGGEST FAIRLY RAPID
EVOLUTION TOWARD BROKEN LINE SEGMENTS WITH EMBEDDED SUPERCELLS. 
THIS ACTIVITY SHOULD FURTHER CONSOLIDATE INTO ONE OR TWO FAIRLY
EXTENSIVE SQUALL LINES...WITH THE SYSTEMS MOVING GENERALLY E ACROSS
THE REMAINDER OF CNTRL TX AND S CNTRL OK LATE THIS EVENING. 
INSTABILITY CONSIDERATIONS...AND EXPECTED STRENGTHENING OF LOW LEVEL
WIND FIELD AS UPR SYSTEMS FINALLY PHASE OVER KS...SUGGEST THAT THE
MCSS WILL CONTINUE TO POSE A THREAT FOR DAMAGING WIND/HAIL AND
PERHAPS ISOLATED TORNADOES AS THEY CROSS THE TX CSTL PLN/NE TX
BETWEEN 09 AND 12Z SATURDAY.

...NRN PLAINS...
STEEP LOW/MID-LEVEL LAPSE RATE PLUME WILL PERSIST BENEATH WEAKENING
NRN STREAM IMPULSE OVER THE NRN PLAINS TODAY.  GIVEN SURFACE
HEATING...NARROW AXIS OF BOUNDARY LAYER DEW POINTS AOA 45 DEG F
BENEATH 500 MB TEMPERATURES AROUND MINUS 20 DEG C SHOULD SUPPORT
SCTD STRONG TSTMS.  VERTICAL SHEAR WILL BE WEAK...BUT SUFFICIENT
INSTABILITY MAY DEVELOP TO FOSTER HAIL IN THE STRONGER UPDRAFTS.

..CORFIDI/CROSBIE.. 04/28/2006