SWODY1
SPC AC 260059
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CDT WED JUL 25 2007
VALID 260100Z - 261200Z
..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NWRN MN...ND AND NRN
SD...
..SYNOPSIS...
MOISTURE CHANNEL IMAGERY AND UPPER AIR ANALYSES INDICATE PATTERN
ACROSS CONUS REMAINS DOMINATED BY SLOWLY RETROGRADING LOW INVOF NWRN
OH/SERN LOWER MI. TROUGH ALOFT EXTENDS SWWD TO WEAKER UPPER LOW
CENTERED OVER ERN COAHUILA NEAR TX/MEX BORDER. BOTH LOWS SHOULD
DRIFT ERRATICALLY THROUGH END OF PERIOD...AS WILL MID/UPPER LEVEL
HIGH LOCATED INVOF NRN CO. SHORTWAVE TROUGH -- NOW EVIDENT OVER
CENTRAL AB -- IS FCST TO MOVE ESEWD ACROSS CANADIAN PRAIRIE
PROVINCES THROUGH 26/12Z. MEANWHILE...WEAK/DIFFUSE UPPER LEVEL
PERTURBATIONS WILL MOVE NNEWD ACROSS GREAT BASIN/NRN ROCKIES
REGIONS.
AT SFC...COLD FRONT WAS ANALYZED AT 23Z FROM FAR NRN ONT SWWD ACROSS
CENTRAL ND TO LOW OVER W-CENTRAL SD...THEN SWWD ACROSS SWRN SD AND
NRN NEB PANHANDLE INTO WY...BECOMING DIFFUSE OVER WY AMIDST
CONVECTIVE OUTFLOWS. FRONT SHOULD BE QUASISTATIONARY DURING
REMAINDER PERIOD ALONG WY/NEB SEGMENT AND MOST OF SD PORTION...WHILE
GENERALLY DRIFTING EWD OVER ND AND EXTREME NWRN MN.
..NRN/CENTRAL PLAINS...
LINE OF TSTMS HAS FORMED AND BECOME LOCALLY SVR INVOF FRONT OVER
SERN MB...EXTENDING SWWD ACROSS NERN ND. POTENTIAL FOR DAMAGING
GUSTS AND HAIL IS EXPECTED TO CONTINUE FOR SEVERAL MORE
HOURS...SUPPORTED TO LARGE EXTENT BY FRONTAL FORCING AND
SUFFICIENTLY ROBUST BOUNDARY LAYER THETAE TO SUPPORT MDTLY-STGLY
UNSTABLE SFC-BASED INFLOW PARCELS. VERY MOIST BOUNDARY LAYER WILL
PERSIST WITH SFC DEW POINTS COMMONLY 70S F OVER ND SUPPORTING
BLENDED WIND/HAIL THREAT...TRENDING SOMEWHAT MORE TOWARD WIND WITH
SWD EXTENT BEFORE ABOUT 04Z AS PREFRONTAL BOUNDARY LAYER ASSUMES
VERY HOT/DEEPLY MIXED CHARACTER. REF SPC MESOSCALE DISCUSSION
1579...AS WELL AS WW 552 AND RELATED MESOSCALE DISCUSSIONS...FOR
MORE DETAILS ON NEAR-TERM SVR THREAT. ALTHOUGH ISOLATED SVR IS
POSSIBLE FARTHER SW OVER NEB PANHANDLE AND CENTRAL
ROCKIES...ORGANIZED SVR POTENTIAL IS FCST TO DIMINISH BOTH WITH SWWD
EXTENT ALONG FRONT...AND WITH TIME AS SFC DIABATIC COOLING REDUCES
BUOYANCY.
..INTERMOUNTAIN W...TO LOWER CO RIVER VALLEY AND SERN CA...
WIDELY SCATTERED TSTMS WILL DIMINISH GRADUALLY IN BOTH COVERAGE AND
INTENSITY OVER THIS REGION THROUGH APPROXIMATELY 06Z AS COMBINATION
OF SFC COOLING AND OUTFLOW AIR REDUCES AVAILABLE BUOYANCY.
HOWEVER...ISOLATED STG-SVR GUSTS ARE POSSIBLE FROM MOST INTENSE
CELLS FOR ANOTHER FEW HOURS.
..SERN CONUS...
WIDELY SCATTERED TSTMS IN CLUSTERS SHOULD PERSIST FOR SEVERAL MORE
HOURS AS FAVORABLY MOIST AIR MASS ONLY SLOWLY COOLS...AND AS OUTFLOW
BOUNDARIES CONTINUE TO FOCUS LIFT ON MESOBETA TO LOCAL SCALES. A
FEW STG-SVR DOWNBURSTS AND MRGL HAIL REPORTS ARE
POSSIBLE...PARTICULARLY BEFORE ABOUT 03Z. THEREAFTER...SVR
POTENTIAL AND OVERALL CONVECTIVE COVERAGE WILL DIMINISH THROUGH
REMAINDER EVENING.
.EDWARDS.. 07/26/2007
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