SWODY1
SPC AC 201630
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT SUN MAY 20 2007
VALID 201630Z - 211200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN HI
PLNS...
..SYNOPSIS...
FAIRLY STRONG UPR LOW NOW CROSSING VANCOUVER ISLAND EXPECTED TO
CONTINUE TO NEAR PDT BY THE END OF THE PERIOD AS LEAD IMPULSE NOW
OVER CNTRL ORE /PER WV IMAGERY/ SWEEPS E/NE TO THE ID/MT BORDER THIS
EVENING...AND INTO SRN SASKATCHEWAN EARLY MONDAY. CYCLOGENESIS
SHOULD OCCUR OVER ERN MT LATER TODAY/TONIGHT WITH APPROACH OF ORE
IMPULSE AND VANCOUVER LOW. THE SFC PATTERN OVER THE NRN HI PLNS
ATTM HAS BEEN COMPLICATED BY OUTFLOW FROM LAST EVENING'S STORMS.
BEST GUESS IS THAT LOW WILL FORM INVOF THE WY/MT BORDER LATE TODAY
..AND DEVELOP NE INTO WRN ND BY 12Z MONDAY. FARTHER E...FRONT NOW
STALLED OVER THE DAKOTAS AND NRN IA SHOULD BEGIN TO EDGE NWD AS A
WARM FRONT AS LOW DEEPENS TO THE WEST.
IN THE SRN STREAM...SRN NM AND FAR W TX WILL CONTINUE TO BE GLANCED
BY NRN FRINGE OF SRN STREAM JET. SATELLITE SUGGESTS PRESENCE OF AN
IMPULSE NOW OVER NRN CHIHUAHUA THAT SHOULD REACH THE ELP AREA THIS
EVENING.
..NRN HI PLNS LATE THIS AFTN INTO TONIGHT...
CONDITIONS WILL GRADUALLY BECOME MORE FAVORABLE FOR TSTMS OVER
CNTRL/ERN MT AND NRN/ERN WY LATER TODAY AS SFC HEATING CONTINUES IN
WAKE OF OVERNIGHT TSTM DEBRIS. A MODIFIED CP AIR MASS REMAINS IN
PLACE ACROSS REGION...WHICH WILL LESSEN DEGREE OF POTENTIAL
DESTABILIZATION. NEVERTHELESS...EVEN WITH MODEST LOW LEVEL
MOISTURE...HEATING SHOULD BOOST MLCAPE TO 1000-2000 J/KG S INVOF
DEVELOPING SFC LOW/WARM FRONT IN SRN MT AND SE ALONG LEE TROUGH INTO
ERN WY INTO WRN SD/NEB. VERTICAL SHEAR WILL REMAIN WEAK OVER MUCH
OF THE WARM SECTOR THROUGH THE AFTERNOON...SUGGESTING THAT STORMS
ALONG THE LEE TROUGH AND WARM FRONT SHOULD BE MAINLY MULTICELL
CLUSTERS...WITH ONLY SHORT-LIVED THREATS FOR SVR WIND/HAIL.
DEEP SHEAR WILL STRENGTHEN OVER NRN WY AND MT LATER TODAY/TONIGHT
WITH APPROACH OF ORE UPR IMPULSE. MORE ORGANIZED/SUSTAINED STORMS
APPEAR LIKELY...INCLUDING SUPERCELLS AND BOWING SEGMENTS. STORMS
SHOULD FORM THIS AFTERNOON ACROSS S CNTRL MT AHEAD OF THE ORE
IMPULSE...WITH ACTIVITY THEN MOVING/DEVELOPING E/NE INTO SE MT AND
THE WRN DAKOTAS TONIGHT. STEEP MID LEVEL LAPSE RATES AND SOMEWHAT
LIMITED BOUNDARY LAYER MOISTURE SUGGEST MAIN SVR THREATS WILL BE
LARGE HAIL/HIGH WIND. DEGREE OF LATTER THREAT WILL...IN PART...BE
DICTATED BY UPSCALE GROWTH OF STORMS INTO FORWARD PROPAGATING
SEGMENTS. ALSO...AS WITH LAST SUNDAY'S EVENT...THREAT WILL ALSO BE
INFLUENCED BY AMOUNT OF HEATING AND PERSISTENCE OF ELY COMPONENT TO
NEAR-SFC FLOW JUST N OF WARM FRONT.
..SRN NM INTO FAR W TX THIS AFTERNOON/EARLY TONIGHT...
WEAK TO MODERATE WSWLY MID LEVEL FLOW...A BIT STRONGER THAN
YESTERDAY...WILL PREVAIL OVER SRN NM/SW TX...DOWNSTREAM FROM NRN
BAJA UPR LOW. FAIRLY RICH BOUNDARY LAYER MOISTURE WITH SFC
DEWPOINTS IN THE MID 50S HAS SPREAD W INTO REGION AND SHOULD PERSIST
THROUGH THE DAY. COUPLED WITH STEEP LOW-MID LEVEL LAPSE RATES AND
APPROACH OF CHIHUAHUAN UPR IMPULSE...SETUP MAY SUPPORT THE
DEVELOPMENT OF A FEW SUSTAINED STORMS/MARGINAL SUPERCELLS...
ESPECIALLY OVER THE HIGHER TERRAIN OF FAR W TX. GIVEN THE SOMEWHAT
MARGINAL NATURE OF THE THREAT...WILL MAINTAIN ONLY LOW SVR
PROBABILITIES ATTM.
.CORFIDI/JEWELL.. 05/20/2007
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