SPC AC 081729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT WED JUN 08 2011
VALID 091200Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM NEW ENGLAND WWD ACROSS THE
MIDWEST/OH VALLEY INTO THE MID MO VALLEY REGION...
...SYNOPSIS...
RIDGING ALOFT IS FORECAST TO PERSIST ACROSS THE S CENTRAL AND SERN
U.S. THIS PERIOD...WITH THE MAIN UPPER TROUGH OVER THE WRN U.S.
FORECAST TO MAKE EWD PROGRESS ACROSS THE INTERMOUNTAIN REGION WITH
TIME. ADDITIONALLY...SMALLER-SCALE DISTURBANCES ARE PROGGED TO
CROSS THE GREAT LAKES/NORTHEAST U.S. WITHIN FAST WLY FLOW -- WITH
THE FLOW FIELD TO BECOME INCREASINGLY CYCLONIC WITH TIME ACROSS THIS
AREA AS THE SRN FRINGE OF AN EWD-MOVING ERN CANADA TROUGH AFFECTS
THIS AREA.
AT THE SURFACE...A COLD FRONT ASSOCIATED WITH THE ERN CANADA TROUGH
IS FORECAST TO CROSS THE LOWER GREAT LAKES/ST. LAWRENCE VALLEY AND
MOVE ACROSS THE NORTHEAST THROUGH THE PERIOD. THE FRONT SHOULD MAKE
LITTLE SWD PROGRESS THOUGH ACROSS THE OH VALLEY...AND WILL LIKELY
BEGIN A NRN RETREAT ON ITS WRN FRINGE AS A WAVE DEVELOPS ALONG THE
BOUNDARY INVOF THE MID MO VALLEY. THIS FRONT -- FROM THE NORTHEAST
WWD INTO THE MID MO VALLEY REGION -- SHOULD BE THE FOCUS FOR THE
PRIMARY AREA OF SEVERE POTENTIAL THIS PERIOD.
...NEW ENGLAND WSWWD INTO THE MIDWEST/OH VALLEY REGION...
STORMS SHOULD BE ONGOING AT THE START OF THE PERIOD ACROSS PORTIONS
OF THE NORTHEAST...WITH LOW-END SEVERE POTENTIAL POSSIBLY ONGOING AS
WELL. POCKETS OF HEATING/DESTABILIZATION SHOULD OCCUR THROUGH THE
MORNING AND AFTERNOON...WHICH WILL SUPPORT MORE WIDESPREAD STORM
DEVELOPMENT NEAR/AHEAD OF THE ADVANCING FRONT. WITH MODERATELY
STRONG DEEP-LAYER WLYS ACROSS THIS REGION...POTENTIAL FOR
DEVELOPMENT OF ORGANIZED/BOWING LINE SEGMENTS APPEARS TO EXIST --
ALONG WITH ASSOCIATED THREAT FOR WIND DAMAGE. HAIL WILL ALSO BE
POSSIBLE -- ESPECIALLY WHERE GREATER DESTABILIZATION CAN OCCUR.
WEAKER FLOW ALOFT FARTHER WWD INTO THE MIDWEST SUGGESTS SOMEWHAT
LESSER SEVERE POTENTIAL...WITH THE GREATEST THREAT LIKELY FROM THE
LOWER GREAT LAKES/UPPER OH VALLEY ENEWD. WHILE POTENTIAL ACROSS THE
ENTIRE REGION SHOULD DECREASE OVERALL INTO THE
EVENING/OVERNIGHT...LIMITED THREAT MAY PERSIST ACROSS SRN NEW
ENGLAND/NY/PA/NJ THROUGH THE EVENING HOURS.
...MID MO VALLEY REGION...
BOUNDARY LAYER EVOLUTION REMAINS DIFFICULT TO ASCERTAIN ATTM ACROSS
THE CENTRAL PLAINS/MID MO VALLEY REGION...WITH THE MODELS
FORECASTING REDEVELOPMENT OF THE HIGH PLAINS LEE LOW NEWD INTO THE
MID MO VALLEY REGION WITH TIME. THOUGH THE WARM SECTOR BOUNDARY
LAYER SHOULD REMAIN CAPPED INTO THE AFTERNOON...MODEL DEPICTIONS OF
A SHORT-WAVE TROUGH MOVING NEWD INTO THE CENTRAL PLAINS AHEAD OF THE
MAIN TROUGH FARTHER W SUGGESTS WEAKENING OF THE CAP...AND SUBSEQUENT
STORM DEVELOPMENT. OVERNIGHT...MORE WIDESPREAD/ELEVATED STORM
DEVELOPMENT IS EXPECTED N OF THE FRONT ACROSS IA AND ERN NEB.
SURFACE-BASED STORM COVERAGE IS A QUESTION ACROSS NERN KS/NRN MO/SRN
IA/FAR SERN NEB. HOWEVER...AMPLE CAPE -- AND SHEAR SUFFICIENT FOR
SUPERCELLS -- SUGGESTS AT LEAST 15% SEVERE PROBABILITIES FOR
HAIL/ISOLATED DAMAGING WINDS AND POSSIBLY A TORNADO OR TWO.
ATTM...WILL NOT UPGRADE THE PROBABILITY DUE TO UNCERTAINTY...BUT
THIS AREA COULD REQUIRE HIGHER SEVERE PROBS IN LATER OUTLOOKS.
OVERNIGHT...HAIL IS ALSO EXPECTED WITH THE ELEVATED STORMS EXPANDING
WITHIN THE WARM ADVECTION REGIME N OF THE SURFACE FRONT.
...APPALACHIANS...
WITH THE UPPER RIDGE ACROSS THE SERN U.S. EXPECTED TO WEAKEN A BIT
THIS PERIOD...ACTIVE AFTERNOON CONVECTION WILL LIKELY DEVELOP --
INITIALLY OVER THE HIGHER TERRAIN OF THE CENTRAL AND SRN
APPALACHIANS. THOUGH THE FLOW FIELD WILL REMAIN QUITE WEAK UNDER
THE UPPER RIDGE...A DEEP BOUNDARY LAYER SUGGESTS POTENTIAL FOR COLD
POOL DEVELOPMENT -- AND THUS THE POSSIBILITY OF POCKETS OF ISOLATED
DAMAGING WITH THREAT INTO EARLY EVENING.
..GOSS.. 06/08/2011
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