DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 310459
SWODY1
SPC AC 310457

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1157 PM CDT THU AUG 30 2012

VALID 311200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE LOWER AND
MID MS VALLEY INTO THE WRN TN VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN NY THROUGH NRN NEW
ENGLAND...

...SYNOPSIS...

REMNANTS OF ISAAC...NOW A TD...IS FORECAST BY NHC TO MOVE IN A
GENERAL NLY DIRECTION BEFORE TURNING NELY LATER FRIDAY NIGHT. THE
CENTER SHOULD APPROACH ECNTRL MO BY 12Z SATURDAY. ELSEWHERE...BELT
OF STRONGER WLYS WILL PERSIST OVER THE NRN TIER OF THE U.S. AND SRN
CANADA. A LOW AMPLITUDE SHORTWAVE TROUGH NOW LOCATED OVER ONTARIO
WILL CONTINUE ESEWD THROUGH QUEBEC AND EVENTUALLY INTO THE NERN
STATES LATER FRIDAY AFTERNOON AND EVENING ACCOMPANIED BY A COLD
FRONT.

...LOWER-MID MS VALLEY REGION...

THE 50+ KT SLY LLJ ASSOCIATED WITH ISAAC WILL SHIFT NWD THROUGH NRN
MS...AR...WRN TN INTO SRN MO...MAINTAINING A FAVORABLE KINEMATIC
ENVIRONMENT FOR ROTATING STORMS AND POSSIBLE ISOLATED TORNADOES.
PRIMARY LIMITING FACTOR THE LAST COUPLE OF DAYS HAS BEEN WEAK
INSTABILITY ASSOCIATED WITH WIDESPREAD CLOUDS ATTENDING THE TROPICAL
CYCLONE. WV AND IR SATELLITE IMAGERY INDICATE SOME MID-UPPER LEVEL
DRY AIR IS BEING ENTRAINED INTO THE TD...AND THIS MAY INCREASE THE
POTENTIAL FOR A FEW MORE CLOUD BREAKS AND BOUNDARY LAYER
DESTABILIZATION BETWEEN CONVECTIVE BANDS. THREAT FOR A FEW MINI
SUPERCELLS AND ISOLATED TORNADOES WILL PERSIST INTO FRIDAY IN
ASSOCIATION WITH THE REMNANTS OF ISAAC.


...NRN NEW YORK THROUGH NRN NEW ENGLAND...

A SLIGHT INCREASE IN LOW LEVEL MOISTURE IS EXPECTED FRIDAY AS SWLY
BOUNDARY LAYER WINDS INCREASE IN PRE-FRONTAL WARM SECTOR. PLUME OF
STEEPER MID LEVEL LAPSE RATES FROM GREAT LAKES INTO SRN CANADA
SHOULD ADVECT INTO THE NERN STATES...WHICH IN ADDITION TO BOUNDARY
LAYER WARMING SHOULD CONTRIBUTE TO 1000-1500 J/KG MLCAPE DURING THE
DAY. THE STRONGER FORCING ATTENDING THE PROGRESSIVE POSITIVE TILT
SHORTWAVE TROUGH WILL LIKELY REMAIN NORTH OF U.S. BORDER...BUT SOME
HEIGHT FALLS WILL OCCUR AS THIS FEATURE APPROACHES THE NERN STATES
DURING THE DAY. POTENTIAL WILL EXIST FOR A FEW SFC BASED DISCRETE
CELLS TO DEVELOP IN THE PRE-FRONTAL WARM SECTOR FROM LATE MORNING
INTO THE AFTERNOON AS THE BOUNDARY LAYER DESTABILIZES AND THE CAP
WEAKENS. WIND PROFILES WILL STRENGTHEN SIGNIFICANTLY WITH THE
APPROACH OF THE UPPER TROUGH WITH 45-55 KT UNIDIRECTIONAL 0-6 KM
SHEAR EXPECTED. A FEW SUPERCELLS AND BOWING SEGMENTS CAPABLE OF
ISOLATED DAMAGING WIND...LARGE HAIL AND PERHAPS A TORNADO OR TWO
WILL BE THE MAIN THREATS.

..DIAL/MOSIER.. 08/31/2012

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