SWODY2
SPC AC 261729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT SAT JUN 26 2010
VALID 271200Z - 281200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE GREAT LAKES
REGION/MIDWEST TO NORTHEAST STATES...
...SYNOPSIS...
MODELS REMAIN CONSISTENT SHOWING WLY FLOW ALOFT THAT HAS BEEN IN
PLACE ALONG THE NRN TIER OF THE U.S. WILL BEGIN AMPLIFYING ON
SUNDAY. THIS TREND IS EXPECTED AS PART OF THE LARGE MID-UPPER LEVEL
VORTEX CENTERED OVER NRN QUEBEC THIS MORNING RETROGRADES WSWWD
ACROSS HUDSON BAY INTO NRN ONTARIO/MANITOBA REGION. HEIGHT RISES
FROM THE NRN HIGH PLAINS TO SASKATCHEWAN...DOWNSTREAM OF UPPER
TROUGH MOVING INTO THE PACIFIC NW...WILL SUPPORT AMPLIFICATION OF A
SEWD MOVING SHORTWAVE TROUGH THROUGH THE UPPER MIDWEST TO THE WRN
GREAT LAKES. MODELS CONTINUE TO SUGGEST MULTIPLE MIDLEVEL IMPULSES
WILL MOVE ENEWD ACROSS THE GREAT LAKES/ OH VALLEY TO NERN STATES IN
ADVANCE OF THE AMPLIFYING UPPER MIDWEST TROUGH. A MORE PROMINENT
WAVE SHOULD WEAKEN SOME AS IT TRACKS FROM THE GREAT LAKES REGION
INTO SRN ONTARIO/ QUEBEC...BUT WILL LIKELY TAKE ON A NEUTRAL TO
SLIGHT NEGATIVE TILT.
AT THE SURFACE...A LOW ATTENDANT TO THE PROMINENT LEAD MIDLEVEL WAVE
SHOULD DEEPEN SOME ON SUNDAY AS IT SHIFTS ENEWD FROM WRN WI AND
THROUGH NRN LOWER MI SUNDAY AFTERNOON TO SWRN QUEBEC BY 12Z MONDAY.
A SECOND UPSTREAM SURFACE LOW ACCOMPANYING THE AMPLIFYING UPPER
MIDWEST SYSTEM SHOULD MOVE SEWD REACHING THE UPPER GREAT LAKES BY
THE END OF THE PERIOD. A COLD FRONT TRAILING THE LEAD SURFACE LOW
WILL SHIFT EWD THROUGH THE GREAT LAKES AND MIDWEST...WHILE THE WRN
EXTENT MOVES SWD INTO THE MID MS VALLEY AND SRN PLAINS.
MEANWHILE...A WARM FRONT IS EXPECTED TO MOVE NEWD FROM THE UPPER OH
VALLEY/CENTRAL APPALACHIANS THROUGH THE NERN STATES DURING THE
FORECAST PERIOD.
...GREAT LAKES REGION/OH VALLEY TO NORTHEAST STATES...
ALTHOUGH STRONGEST LOW LEVEL MASS FLUX SHOULD SHIFT EWD FROM THE
UPPER GREAT LAKES/NRN LOWER MI INTO SRN ONTARIO/SWRN QUEBEC BY
SUNDAY AFTERNOON...INCREASING SWLY LOW LEVEL WINDS ACROSS THE OH
VALLEY ALONG SRN EXTENT OF THE LLJ WILL ADVECT MOISTURE NEWD. HIGH
THETAE AIR MASS...PW VALUES /1.5-2 INCHES/...SPREADING NEWD
SPREADING NEWD ACROSS THE WARM SECTOR COMBINED WITH SURFACE HEATING
WILL RESULT IN MODERATE INSTABILITY THROUGHOUT THE SLIGHT RISK AREA.
TSTMS...POTENTIALLY IN THE FORM OF AN MCS...SHOULD BE ONGOING AT 12Z
SUNDAY ACROSS THE WRN GREAT LAKES INTO PARTS OF THE MIDWEST. NEW
TSTMS ARE EXPECTED TO DEVELOP BY SUNDAY AFTERNOON ALONG A
PRE-FRONTAL BOUNDARY/CONVERGENCE ZONE FROM THE MID MS/LOWER OH
VALLEYS INTO LOWER MI AND POTENTIAL WILL EXIST FOR THE MORNING MCS
TO RE-INTENSITY AS IT MOVES EWD INTO A DESTABILIZING AIR MASS. DEEP
LAYER SHEAR SHOULD BE STRONGEST OVER THE GREAT LAKES WHERE
SUPERCELLS WILL BE POSSIBLE...WITH MULTICELLULAR CLUSTERS/LINE
SEGMENTS MORE LIKELY INTO THE OH VALLEY GIVEN WEAKER SHEAR VALUES
WITH SWD EXTENT. ADDITIONAL TSTM DEVELOPMENT IS EXPECTED IN THE
VICINITY OF THE RETREATING WARM FRONT SUNDAY AFTERNOON WITH MODERATE
INSTABILITY AND EFFECTIVE BULK SHEAR SUFFICIENT FOR ORGANIZED
STORMS...INCLUDING A FEW SUPERCELLS.
AMPLE LARGE SCALE ASCENT AND A STRENGTHENING WEST-SOUTHWESTERLY LOW
LEVEL JET...AHEAD OF THE UPSTREAM AMPLIFYING SHORTWAVE TROUGH...
SHOULD CONTRIBUTE TO THE ORGANIZATION/SUSTENANCE OF MULTIPLE
EASTWARD MOVING LINEAR CLUSTERS/POTENTIAL MCS DURING THE EVENING
HOURS...ESPECIALLY ACROSS THE LOWER GREAT LAKES VICINITY. THIS
ACTIVITY MAY ULTIMATELY OUTRUN THE GREATER RESERVOIR OF INSTABILITY
ACROSS THE MIDWEST SUNDAY NIGHT...BUT AT LEAST SPORADIC WIND DAMAGE
MAY BE POSSIBLE LATE SUNDAY NIGHT/EARLY MONDAY AS FAR EAST AS
UPSTATE NY AND WESTERN NEW ENGLAND.
...MID MS VALLEY TO SRN/CENTRAL HIGH PLAINS...
AIR MASS IS EXPECTED TO BECOME MODERATELY TO STRONGLY UNSTABLE ALONG
THE SWD MOVING COLD FRONT WITH GREATEST VALUES EXTENDING FROM MO
THROUGH SRN KS AND OK. LOW LEVEL CONVERGENCE WILL HELP TO PROMOTE
TSTM DEVELOPMENT ALONG THE FRONT. STRONGER SHEAR IS PROGGED TO LAG
THIS BOUNDARY RESULTING IN A LIMITED POTENTIAL FOR ORGANIZED STORMS.
HOWEVER...GIVEN STRONG INSTABILITY...ISOLATED WIND GUSTS AND HAIL
WILL BE POSSIBLE.
ADDITIONAL STORMS WILL BE LIKELY INTO THE HIGHER TERRAIN AND
ADJACENT HIGH PLAINS OF ERN CO/NM AS MOIST POST FRONTAL UPSLOPE FLOW
OCCURS ACROSS MUCH OF THESE AREAS...AND SELY UPSLOPE FLOW INTO SW TX
IN ADVANCE OF THE FRONT SUPPORT AFTERNOON CONVECTION. ALTHOUGH DEEP
LAYER SHEAR WILL BE STRONGER ACROSS THIS AREA... WEAKER INSTABILITY
WILL TEND TO LIMIT COVERAGE OF THE SEVERE WEATHER THREAT.
..PETERS.. 06/26/2010
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