SWODY2
SPC AC 101729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT MON SEP 10 2007
VALID 111200Z - 121200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
UPPER TROUGH CURRENTLY FROM CNTRL CANADA SWD INTO THE CNTRL PLAINS
WILL MOVE EAST INTO THE GREAT LAKES...OH VALLEY AND NERN STATES
TUESDAY. EMBEDDED WITHIN THE UPPER TROUGH...A LEAD SHORTWAVE TROUGH
NOW OVER THE CNTRL PLAINS WILL ADVANCE EWD INTO THE MID ATLANTIC
SEABOARD TUESDAY AFTERNOON. AN UPSTREAM IMPULSE WILL DROP SEWD
THROUGH THE GREAT LAKES BEFORE EJECTING ENEWD THROUGH NY DURING THE
AFTERNOON. A SURFACE LOW IS FORECAST TO DEVELOP IN ASSOCIATION WITH
THIS IMPULSE AND LIFT NEWD THROUGH THE LOWER GREAT LAKES AREA. THIS
WILL PROVIDE THE IMPETUS FOR A COLD FRONT TO ADVANCE EWD INTO THE
NERN STATES WHILE A WARM FRONT LIFTS NWD INTO SRN NEW ENGLAND.
..CNTRL AND ERN NY THROUGH PARTS OF NEW ENGLAND...
MID 60S LOW LEVEL DEWPOINTS OVER PA WILL ADVECT NWD INTO PRE-FRONTAL
WARM SECTOR ACROSS CNTRL AND ERN NY AND SRN NEW ENGLAND TUESDAY AS
SSWLY FLOW BECOMES ESTABLISHED EAST OF DEVELOPING LOW. PRIMARY
CONCERN IS LIKELIHOOD OF VERY MARGINAL INSTABILITY DUE TO WEAK MID
LEVEL LAPSE RATES AND POTENTIAL FOR CLOUDS AND PRECIPITATION OVER
PARTS OF WARM SECTOR. BOTH NAM AND GFS SUGGEST A DOUBLE LOW LEVEL
JET STRUCTURE DEVELOPING TUESDAY WITH ONE FROM THE MID ATLANTIC INTO
SRN NEW ENGLAND IN ASSOCIATION WITH HEIGHT FALLS ATTENDING LEAD
SHORTWAVE TROUGH...AND ANOTHER FARTHER WEST IN VICINITY OF
BAROCLINIC ZONE. WARM ADVECTION ACCOMPANYING ERN MOST LOW LEVEL JET
WILL CONTRIBUTE TO CLOUDS AND SHOWERS FROM THE MID ATLANTIC NEWD
INTO SRN NEW ENGLAND...LIMITING INSTABILITY IN THIS REGION MUCH OF
THE DAY. A SLIGHTLY BETTER CHANCE FOR DESTABILIZATION MAY EXIST
FARTHER NW ACROSS PARTS OF NY WHERE DEVELOPING SWLY LOW LEVEL JET
MAY CONTRIBUTE TO LOW CLOUDS MIXING OUT JUST AHEAD OF THE FRONT. IF
THIS OCCURS...MLCAPE AOB 500 J/KG WILL BE POSSIBLE. STRENGTHENING
LOW-MID LEVEL WINDS AND FORCING FOR ASCENT IN VICINITY OF COLD FRONT
DOWNSTREAM FROM IMPULSE MOVING ENEWD THROUGH THE GREAT LAKES WILL
RESULT IN THE POTENTIAL FOR ORGANIZED STORMS. THREAT WILL EXIST FOR
LINE SEGMENTS WITHE EMBEDDED SUPERCELL AND LEWP STRUCTURES IF
SUFFICIENT INSTABILITY DEVELOPS. GIVEN THE CONDITIONAL NATURE OF THE
THREAT...WILL MAINTAIN 5% SEVERE PROBABILITIES AT THIS TIME...BUT
AREA WILL CONTINUE TO BE EVALUATED FOR AN UPGRADE TO SLIGHT RISK IN
DAY 1 OUTLOOKS.
.DIAL.. 09/10/2007
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