SWODY1
SPC AC 010058
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 PM CDT WED AUG 31 2011
VALID 010100Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS MT-ND...
...SYNOPSIS...
UPPER-AIR PATTERN REMAINS DOMINATED BY INTENSE ANTICYCLONE CENTERED
OVER SRN PLAINS...WITH RIDGING EXTENDING WWD TO NRN BAJA...EWD
ACROSS GA...AND NNEWD ACROSS MN. SYNOPTIC-SCALE TROUGH...WITH
SEVERAL EMBEDDED SHORTWAVES...IS EVIDENT IN MOISTURE CHANNEL IMAGERY
FROM NRN AB SWWD ACROSS CANADIAN ROCKIES TO INTERIOR PAC NW AND NRN
CA. THIS TROUGH WILL BECOME MORE POSITIVELY TILTED OVERNIGHT AS NRN
PORTION MOVES EWD ALONG CANADIAN BORDER TO NWRN MT.
AT SFC...CYCLONE ANALYZED AT 23Z OVER SERN MT...IS EXPECTED TO FILL
SOMEWHAT AND LIFT NEWD TOWARD ERN ND...WHILE TRAILING COLD FRONT
MOVES SEWD ACROSS WRN/CENTRAL SD AND NERN/E-CENTRAL WY.
QUASISTATIONARY FRONT...INITIALLY ANALYZED FROM LOW NEWD ACROSS NERN
MT TO SERN SK...SHOULD START MOVING EWD IN STEP WITH ZONAL COMPONENT
OF CYCLONE MOTION THROUGH EVENING AND OVERNIGHT. DOUBLE-STRUCTURED
WARM FRONTAL ZONE WAS ANALYZED...PRIMARY BOUNDARY INTERSECTING
QUASISTATIONARY FRONT OVER E-CENTRAL MT NE OF SFC LOW...AND
EXTENDING SEWD ACROSS SWRN ND AND CENTRAL SD. SECONDARY WARM FRONT
WAS DRAWN FROM N-CENTRAL ND SEWD OVER NERN SD AND S-CENTRAL MN.
BOTH WARM FRONTAL ZONES SHOULD MOVE NEWD OVERNIGHT...SRN ONE
SOMEWHAT FASTER AND REACHING S-CENTRAL ND AND SWRN MN BY ABOUT 12Z.
...MT-ND...
SVR POTENTIAL THROUGH REMAINDER EVENING AND OVERNIGHT WILL ARISE
FROM SOME BLEND OF TWO REGIMES...
1. POST COLD-FRONTAL TSTMS ACROSS MT THAT SHOULD CONTINUE TO MOVE
NEWD ACROSS ERN MT BEHIND FRONT...WITH OCNL POTENTIAL FOR LARGE HAIL
AND STG-SVR GUSTS. THIS ACTIVITY WILL BE SUSTAINED BY COMBINATION
OF MOIST TRAJECTORIES FROM NELY DIRECTION...AND STEEP LAPSE RATES
ABOVE FRONTAL ZONE...PER GGW RAOB MODIFIED FOR NEARBY POSTFRONTAL
CONDITIONS.
2. TSTMS OVER SERN MT..WHETHER THOSE CURRENTLY CROSSING INTO WARM
SECTOR FROM BEHIND FRONTAL ZONE OR ADDITIONAL DEVELOPMENT NEAR WARM
FRONT...MOVING NEWD OVER WRN ND...ALSO WITH RISK FOR LARGE HAIL.
WIND THREAT WILL DEPEND ON ORGANIZATION OF AGGREGATE COLD POOL
BEFORE ACTIVITY CROSSES OVER SUFFICIENTLY DEEP LAYER OF SFC-BASED
STATIC STABILITY NE OF PRIMARY WARM FRONT.
UPSCALE GROWTH AND INCREASING TSTM COVERAGE IS POSSIBLE ACROSS
OUTLOOK AREA FROM EITHER OF THESE SOURCES...ESPECIALLY NEAR AND NE
OF QUASISTATIONARY AND WARM FRONTS WHERE ELEVATED LLJ AND RELATED
WAA WILL FOCUS ASCENT AND MOISTURE TRANSPORT.
...REMAINDER CENTRAL/NRN PLAINS...
FARTHER S...SVR POTENTIAL IS MORE CONDITIONAL AND ISOLATED...WITH
POTENTIAL FOR HAIL/GUSTS RELATED TO EITHER
1. HIGH-BASED TSTMS ABOVE HOT/WELL-MIXED SUBCLOUD AIR MASS FOR 2-3
MORE HOURS...NOW MOVING NEWD OUT OF WRN NEB AND
2. HAIL-PRODUCING DEVELOPMENT ALONG AND NE OF SFC WARM FRONT OVER
ERN SD...WHERE LARGE BUOYANCY WILL EXIST ATOP INVERSION SERVING AS
BASE OF EML.
..EDWARDS.. 09/01/2011
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