SWODY1
SPC AC 290540
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM CDT WED AUG 29 2007
VALID 291200Z - 301200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CNTRL
GRTLKS REGION...
..CNTRL GRTLKS REGION...
PHASED SUB-TROPICAL AND POLAR WLY TROUGH WILL MOVE QUICKLY EWD
ACROSS THE GRTLKS REGION AND UPR MIDWEST WEDNESDAY AFTN. PRIMARY
LARGE SCALE HEIGHT FALLS WILL PASS THROUGH CANADA...BUT AT LEAST
WEAK FORCING FOR ASCENT WILL SKIRT THE UPR MIDWEST. AT THE SFC...A
COLD FRONT...NOW ANALYZED FROM LWR MI TO IA...WILL SETTLE SEWD INTO
SERN LWR MI...NRN IND AND CNTRL IL BY LATE WEDNESDAY EVENING.
IMMEDIATELY ALONG/AHEAD OF THE FRONT...BOUNDARY LAYER WILL BECOME
QUITE MOIST WITH SFC DEW POINTS IN THE UPR 60S/LWR 70S. MID-LEVEL
LAPSE RATES ARE NOT EXPECTED TO BE TERRIBLY STEEP...BUT VERY WARM
BOUNDARY LAYER WILL BOOST MLCAPES INTO THE 1000-1500 J/KG RANGE.
THOUGH INHIBITION WILL BE MODEST...DEEPENING FRONTAL
CIRCULATION...AIDED BY WEAK SUPPORT ALOFT...SHOULD SUFFICIENTLY
ERASE INHIBITION FOR TSTM DEVELOPMENT FROM LWR MI SWWD INTO NRN IL
BY MID-AFTN.
DESPITE THE EXPECTATION OF BULK SHEAR VALUES TO WEAKEN THROUGH THE
DAY...THE DEEP LAYER UNIDIRECTIONAL WSWLY FLOW WILL LIKELY FOSTER
FAST MOVING LINE SEGMENTS/BOWS GIVING DMGG WIND GUSTS. ACTIVITY
SHOULD DECREASE AFTER SUNSET AS PRIMARY MASS CONVERGENCE SHIFTS NEWD
AND BOUNDARY LAYER COOLS.
..CNTRL HIGH PLAINS...
LOW-LEVEL FLOW WILL TURN SELY ON WEDNESDAY BEHIND A COLD FRONT
MOVING SWD ACROSS THE CNTRL HIGH PLAINS. LOW-LEVEL MOISTURE WILL
ADVECT NWD...LIKELY HUGGING THE LARAMIE RANGE AND CO FOOTHILLS.
WHILE FORECAST SOUNDINGS SUGGEST THAT THE PLAINS WILL REMAIN
CAPPED...SUFFICIENT BUOYANCY SHOULD DEVELOP ALONG THE ERN SLOPES TO
SUPPORT WDLY SCT TSTM DEVELOPMENT BY LATE WEDNESDAY AFTN. A WEAK
DISTURBANCE MIGRATING FROM THE NRN GRT BASIN MAY AUGMENT VERTICAL
MOTION FIELDS FOR ISOLD STRONGER STORMS BY LATE AFTN. MLCAPES OF
1000-1500 J/KG AND AT LEAST 30-35 KTS OF 0-6KM SHEAR SHOULD SUPPORT
ISOLD LARGE HAIL AND PERHAPS GUSTY WINDS WITH THE MORE ROBUST
STORMS. ACTIVITY SHOULD STAY CLOSER TO THE HIGHER TERRAIN AND
DIMINISH BY LATE EVENING.
..SRN HIGH PLAINS...
LEADING COLD FRONT...AUGMENTED BY OUTFLOW AIR...WILL MOVE SWD ACROSS
THE NM/TX HIGH PLAINS WEDNESDAY AFTERNOON. LOW-LEVEL FLOW TURNS
MORE NELY BY LATE AFTN AND WILL LIKELY SUPPORT A CLUSTER OR TWO OF
TSTMS MOVING FROM NERN NM MOUNTAINS INTO ECNTRL NM AND THE TX HIGH
PLAINS DURING THE EVENING. OTHER STORMS MAY ALSO FORM ALONG THE
COLD FRONT EWD INTO THE LWR TX S PLAINS WHERE STEEP LOW LEVEL LAPSE
RATES WILL CONTRIBUTE TO MODEST BUOYANCY. VERTICAL SHEAR WILL BE
QUITE ANEMIC...BUT INCREASING DEEP NLY FLOW REGIME AND WELL-MIXED
BOUNDARY LAYER TO THE S OF THE COLD FRONT MAY LEAD TO MODEST SWD
MOVING LINE SEGMENTS WITH ISOLD SVR WIND GUSTS.
.RACY/CROSBIE.. 08/29/2007
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