SWODY1
SPC AC 131257
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 AM CDT SUN MAY 13 2007
VALID 131300Z - 141200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN HI
PLNS/NRN PLNS...
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE UPR MS
VLY/UPR GRT LKS...
..SYNOPSIS...
CNTRL WA UPR LOW EXPECTED TO CONTINUE E/NE INTO NRN ID/WRN MT TODAY
BEFORE WEAKENING AS IT BECOMES ABSORBED WITHIN LARGER SCALE TROUGH
EVOLVING OVER SASKATCHEWAN/ERN MT ON MONDAY. ATTENDANT SFC CENTER
NOW OVER SE MT LIKELY WILL REMAIN MORE OR LESS STATIONARY TODAY.
THE LOW SHOULD ELONGATE NE INTO THE ERN DAKOTAS/NW MN TONIGHT AND
EARLY MONDAY AS TRAILING COLD FRONT ACCELERATES SE ACROSS THE NRN HI
PLNS. WARM FRONT NOW OVER THE LWR MO VLY SHOULD EDGE E/NE INTO THE
UPR MS VLY THIS AFTERNOON AND REACH THE UPR GRT LKS EARLY MONDAY.
ELSEWHERE...WEAK UPR TROUGH WILL PERSIST FROM N TX E/SE ACROSS THE
NRN GULF OF MEXICO INTO CNTRL FL. COLD FRONT ASSOCIATED WITH
AMPLIFYING NERN STATES TROUGH LIKELY WILL BECOME ILL-DEFINED AS IT
MOVES FARTHER S ACROSS THE SERN STATES/LWR TN VLY.
..SRN MT/NRN WY INTO SWRN ND/NWRN SD...
COMBINATION OF SFC HEATING AND INCREASING UVV AHEAD OF EWD-MOVING WA
UPR LOW LIKELY WILL LEAD TO TSTM DEVELOPMENT OVER THE HIGHER TERRAIN
OF WRN MT AND NRN ID A BIT LATER TODAY...WHERE SPARSE MOISTURE WILL
LIMIT DEGREE OF DESTABILIZATION. SOMEWHAT GREATER INSTABILITY
/SBCAPE TO 2000 J PER KG/ WILL DEVELOP OVER ERN AND SRN MT...WHERE
STEEP LOW TO MID LEVEL LAPSE RATES WILL EXIST WITH SFC DEWPOINTS IN
THE UPR 40S/LOW 50S F.
CONTINUED EWD MOVEMENT OF UPR SYSTEM AND ASSOCIATED REDUCTION OF CIN
SHOULD ALLOW STORMS TO MOVE/DEVELOP E ACROSS CNTRL MT BY MID TO LATE
AFTERNOON...WITH A THREAT FOR HIGH WIND AND HAIL. OTHER STORMS MAY
FORM LATER THIS AFTERNOON INVOF SFC LOW IN SERN MT/SW ND/NW SD AND
PERHAPS FAR NRN WY. 40-50 KT DEEP SWLY SHEAR ON SERN FLANK OF UPR
SYSTEM...ALONG WITH WEAK BUT BACKED NEAR-SFC FLOW NEAR SFC LOW WILL
CREATE FAVORABLE ENVIRONMENT FOR DISCRETE SUPERCELLS IN THIS
REGION...WITH A CONDITIONAL THREAT FOR TORNADOES IN ADDITION TO
LARGE HAIL/HIGH WIND. THE SEVERE THREAT SHOULD SHIFT FARTHER E INTO
THE DAKOTAS TONIGHT...WHERE UPSCALE DEVELOPMENT INTO AN MCS OR TWO
WILL BE ACCOMPANIED BY A GRADUALLY DIMINISHING POTENTIAL FOR
WIND/HAIL.
..NRN MN/NRN WI/UPPER MI...
SCTD AREAS OF ELEVATED STORMS LIKELY WILL PERSIST THROUGHOUT THE
PERIOD IN WARM ADVECTION ZONE OVER THE UPR MS VLY/UPR GRT LKS. SOME
OF THESE ON OCCASION MAY PRODUCE MARGINALLY SEVERE HAIL.
IN GENERAL...THE UPR MS VLY REGION WILL REMAIN ON NRN FRINGE OF
CNTRL PLNS RIDGE...WITH LARGE-SCALE SUBSIDENCE MAINTAINING A
PERSISTENT CAP.
IN NRN MN EWD INTO NRN WI/UPR MI...HOWEVER...IT APPEARS THAT A WEAK
SHORT-WAVE IMPULSE TOPPING THE RIDGE WILL PROVIDE SUFFICIENT UVV TO
SUPPORT MORE ROBUST ELEVATED STORMS BY LATE THIS AFTERNOON /EARLY
TONIGHT. WHILE DEGREE OF INSTABILITY SHOULD REMAIN LIMITED
..CLOUD-LAYER SHEAR WILL BE SUFFICIENT FOR ORGANIZED/ROTATING
STORMS WITH A POTENTIAL FOR HAIL. THIS ACTIVITY SHOULD
INCREASE IN COVERAGE WHILE SHIFTING EWD ACROSS THE UPR GRT LKS
TONIGHT IN RESPONSE TO STRENGTHENING LLJ. THE SEVERE THREAT
SHOULD SLOWLY DIMINISH AS THE STORMS MOVE INTO A LESS
FAVORABLE THERMODYNAMIC ENVIRONMENT EARLY MONDAY.
.CORFIDI/TAYLOR.. 05/13/2007
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