SPC AC 310100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT THU AUG 30 2007
VALID 310100Z - 311200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
UPPER AIR PATTERN WILL CONTINUE TO FEATURE ERN TROUGH EXTENDING SWD
FROM HUDSON BAY VORTEX ACROSS MID-ATLANTIC REGION...AND RIDGING FROM
4-CORNERS AREA ANTICYCLONE NWD OVER NRN ROCKIES TO ERN AB/WRN SASK.
MID-UPPER LEVEL TROUGHING AND ACCOMPANYING CYCLONIC SHEAR ZONE WILL
EXTEND FROM UPPER LOW OVER W-CENTRAL MEX...NEWD ACROSS ARKLATEX
REGION AND WRN TN...THEN MERGING WITH MEAN TROUGH OVER NERN CONUS.
QUASISTATIONARY/WEAK UPPER TROUGH ALSO IS EVIDENT IN MOISTURE
CHANNEL IMAGERY FROM PNS/MOB AREA SWWD ACROSS W-CENTRAL/SERN GULF.
AT SFC...COLD FRONT IS ANALYZED FROM NWRN ONT SWWD ACROSS NERN MN
AND NRN ND...MOVING SSEWD. FRONT SHOULD SETTLE OVER SWRN THROUGH
E-CENTRAL ND AND EXTREME N-CENTRAL MN TONIGHT BEFORE DECELERATING.
MEANWHILE...PERSISTENT...WAVY AND OUTFLOW-DIFFUSED FRONTAL ZONE IS
EVIDENT FROM E-CENTRAL NM EWD ACROSS RED RIVER REGION OF
TX/OK...ENEWD OVER SRN APPALACHIANS...THEN NEWD ACROSS MAINE. NEW
ENGLAND/MID ATLANTIC PORTION OF FRONT WILL PROCEED OFFSHORE...WHILE
REMAINDER OF FRONT DRIFTS SEWD/SWD.
....MN/ND...
ISOLATED BAND OF TSTMS WILL CONTINUE TO MOVE SEWD ACROSS PORTIONS
EXTREME ERN ND AND NWRN MN FOR A FEW MORE HOURS...AS LOW LEVEL
CONVERGENCE NEAR COLD FRONT PROVIDES SUFFICIENT LIFT. MRGLLY SVR
HAIL AND STG/DAMAGING GUSTS MAY OCCUR IN MORE INTENSE CELLS...BUT
THREAT APPEARS TOO BRIEF/ISOLATED AND LIMITED IN SPATIAL EXTENT TO
WARRANT CATEGORICAL OUTLOOK. THIS ACTIVITY MAY TEND TO BACKBUILD
WWD INTO SFC MOIST AXIS...WHICH IS ANALYZED FROM N-CENTRAL SD NEWD
ACROSS NERN ND. HOWEVER...ADDITIONAL DEVELOPMENT WILL BE LIMITED BY
CAPPING LOCATED AT BASE OF ELEVATED MIXED LAYER...AROUND 700 MB.
THOUGH VERTICAL SHEAR WILL REMAIN FAVORABLE...WITH EFFECTIVE SHEAR
40-50 KT...STRENGTHENING SBCINH RELATED TO DIABATIC SFC COOLING WILL
LIMIT SVR POTENTIAL WITH TIME AFTER ABOUT 03Z.
...ORE/NRN CA...
SCATTERED-NUMEROUS TSTMS HAVE DEVELOPED FROM KLAMATH MOUNTAINS OF
NWRN CA NWD THEN NEWD OVER PORTIONS SWRN/CENTRAL ORE. KINEMATIC
PROFILES BENEATH BELT OF MIDLEVEL SWLYS APPEARS MRGLLY FAVORABLE
OVER THIS AREA...WITH 40-45 KT EFFECTIVE SHEAR. MODIFIED MFR RAOB
AND RUC SOUNDINGS SUGGEST STEEP LOW-MIDLEVEL LAPSE RATES AND 40S/50S
F SFC DEW POINTS OVER MUCH OF THIS AREA SUPPORT 500-1000 J/KG
MLCAPE. FAVORABLE BUOYANCY SHOULD PERSIST FOR ANOTHER 2-3 HOURS IN
PRECONVECTIVE AIR MASS...UNTIL DIABATIC SFC COOLING ACCELERATES AND
INCREASES SBCINH. GEN DECREASE IN CONVECTIVE COVERAGE AND INTENSITY
IS FCST AFTER 03Z...THOUGH ISOLATED HAIL/GUSTS NEAR SVR LEVELS STILL
WILL BE POSSIBLE THROUGH LATE EVENING FROM MOST INTENSE CELLS.
...ELSEWHERE...
WIDELY SCATTERED TSTMS -- MUCH OF THEM IN BANDS AND MULTICELLULAR
CLUSTERS -- WILL CONTINUE THROUGH REMAINDER EVENING FROM ERN NEW
ENGLAND SWWD ACROSS GA...MS DELTA REGION...AND CENTRAL/WRN TX.
OVERALL COVERAGE/INTENSITY OF CONVECTION WILL DIMINISH FROM NOW
THROUGH REMAINDER EVENING AS BOUNDARY LAYER STABILIZES...FROM
COMBINATION OF DIABATIC EFFECTS RELATED TO OUTFLOW AND LOSS OF
INSOLATION. DEEP-LAYER SHEAR WILL REMAIN QUITE WEAK FROM
MID-ATLANTIC REGION SWWD AS WELL. WHILE VERY BRIEF/ISOLATED
CONVECTIVE WIND EVENT CANNOT BE RULED OUT...SVR POTENTIAL APPEARS
TOO ISOLATED FOR 5 PERCENT RISK AREA ATTM.
..EDWARDS.. 08/31/2007
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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