SWODY1
SPC AC 081243
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0743 AM CDT SAT SEP 08 2007
VALID 081300Z - 091200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER A SMALL PART OF SRN NY/NRN
PA AND NEW ENGLAND...
..SYNOPSIS...
BROAD LOW AMPLITUDE TROUGH WILL PERSIST FROM THE NRN RCKYS TO THE
UPR MS VLY THIS PERIOD...N OF ELONGATED RIDGE EXTENDING FROM THE SRN
RCKYS ACROSS THE LWR MS VLY TO THE MID ATLANTIC CST. STRONG IMPULSE
THAT CROSSED THE UPR GRT LKS YESTERDAY WILL CONTINUE ENE INTO ERN
QUEBEC AS ASSOCIATED COLD FRONT SETTLES SLOWLY S/SE ACROSS NEW
ENGLAND...THE LWR OH VLY AND THE SRN PLNS.
FARTHER W...IMPULSE NOW IN CNTRL MT SHOULD CONTINUE E INTO NRN MN
AND WEAKEN TONIGHT/EARLY SUNDAY AS UPSTREAM DISTURBANCE IN CNTRL BC
AMPLIFIES SE INTO THE NRN RCKYS. FAIRLY STRONG FRONT WITH MT SYSTEM
WILL NOSE S ACROSS WRN PORTIONS OF SD AND NEB...WHILE ERN PART OF
SAME BOUNDARY REMAINS MORE DIFFUSE AND MOVES SLOWLY S ACROSS THE UPR
MS VLY/UPR GRT LKS.
..SRN NY/NRN PA INTO CNTRL/SRN NEW ENGLAND...
MODERATE HEATING WILL OCCUR S OF COLD FRONT AND DEFORMATION CLOUD
BAND ACROSS PARTS OF THE NERN STATES TODAY...WHERE RECORD OR
NEAR-RECORD MAX SFC TEMPERATURES MAY OCCUR. BUT MID LVL LAPSE
RATES...LARGE SCALE FORCING FOR ASCENT AND CONVERGENCE WILL BE WEAK
AS LEAD UPR IMPULSE LIFTS RAPIDLY ENE INTO QUEBEC. A BAND OF SCTD
TO BROKEN STORMS SHOULD NEVERTHELESS FORM AHEAD OF FRONT AND
AFOREMENTIONED CLOUD BAND OVER PARTS OF NEW ENGLAND...NY AND PA.
GIVEN MLCAPE OF 1500 TO PERHAPS TO 2000 J/KG...MODEST UNIDIRECTIONAL
WSW FLOW SHOULD SUPPORT MULTICELLULAR CLUSTERS THAT COULD YIELD A
FEW SPOTS OF LOCALLY DAMAGING WIND.
..W TX INTO OK...
POCKETS OF STRONG HEATING AND RICH BOUNDARY LYR MOISTURE WILL
RESULT IN AREAS OF WEAKLY-CAPPED MODERATE INSTABILITY /MLCAPE TO
2000 J PER KG/ THIS AFTERNOON ALONG AND S OF COLD FRONT/COMPOSITE
OUTFLOW BOUNDARIES FROM W TX INTO SRN OK. DEEP SHEAR AND LARGE
SCALE ASCENT WILL BE WEAK. BUT GIVEN HI PWS...A FEW STORMS COULD
YIELD LOCALLY DAMAGING WIND GUSTS EARLY IN THEIR DEVELOPMENT. THIS
ACTIVITY SHOULD ONCE AGAIN EVOLVE INTO SEVERAL SLOWLY-MOVING
CLUSTERS WITH VERY HEAVY RAIN ACROSS PARTS OF OK AND AR
TONIGHT/EARLY SUNDAY.
..ERN DAKS/FAR WRN MN SW INTO CNTRL NEB/NW KS/ERN CO...
LOW LVL ASCENT SHOULD FOCUS ALONG COLD FRONT AND PREFRONTAL TROUGH
OVER ERN SD/CNTRL NEB AND NW KS LATER TODAY AS MT UPR SYSTEM
CONTINUES EWD. WITH RICH BOUNDARY LYR MOISTURE REMAINING CONFINED
TO AREAS ALONG AND S OF FRONT OVER THE SRN PLNS...MLCAPE LIKELY WILL
BE LIMITED TO AOB 500 J/KG DESPITE CONSIDERABLE SFC HEATING.
NEVERTHELESS...LOW LEVEL CONVERGENCE AND MODEST LARGE UVV ON FRINGE
OF PASSING UPR DISTURBANCE SHOULD PROMOTE DEVELOPMENT OF A BAND OF
DIURNAL STORMS. GIVEN MODERATE...DEEP UNIDIRECTIONAL WLY SHEAR...
THERMODYNAMIC PROFILES COULD YIELD A FEW SVR WIND GUSTS AND/OR
MARGINALLY SVR HAIL. OTHER STORMS MAY FORM IN WARM ADVECTION ZONE
ACROSS ND AND WRN/NRN MN. THIS ACTIVITY SHOULD REMAIN ELEVATED AND
POSE MINIMAL SVR THREAT.
.CORFIDI/JEWELL.. 09/08/2007
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