Categorical Graphic
Probabilistic Tornado Graphic
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.

   SPC AC 080558
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1258 AM CDT WED JUN 08 2011
   
   VALID 081200Z - 091200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES SWWD INTO
   IA/NRN MO AND WWD THROUGH THE CENTRAL PLAINS TO NERN CO/SERN WY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NORTHEAST
   STATES...
   
   ...SYNOPSIS...
   MODELS REMAIN RELATIVELY CONSISTENT WITH THE UPPER AIR PATTERN
   SHOWING THE WRN U.S. INTO THE NRN ROCKIES/HIGH PLAINS BEING
   DOMINATED BY A POSITIVELY-TILTED MEAN TROUGH...WHILE A STRONG RIDGE
   IS MAINTAINED FROM NRN MEXICO/SRN PLAINS TO NEW ENGLAND.  STRONG
   SWLY MID-UPPER LEVEL WINDS WILL BE LOCATED BETWEEN THESE PRIMARY
   LARGE SCALE CONUS UPPER AIR FEATURES...FROM THE DESERT SW TO THE
   GREAT LAKES...WITH THE FLOW THEN EXTENDING EWD TO NEW ENGLAND.  A
   SHORTWAVE TROUGH WILL TRACK ENEWD FROM NRN MN/ADJACENT ONTARIO THIS
   MORNING AND DE-AMPLIFY AS IT PROGRESSES INTO CONFLUENT FLOW REGIME
   EXTENDING EWD INTO SRN QUEBEC.  MEANWHILE...AN UPSTREAM SHORTWAVE
   TROUGH...CURRENTLY MOVING SWD THROUGH THE PACIFIC NORTHWEST...WILL
   TURN MORE SEWD TODAY TRACKING ACROSS THE NRN INTERMOUNTAIN
   WEST/ROCKIES.
   
   AT 12Z TODAY...AN AREA OF LOW PRESSURE IS EXPECTED TO TRACK FROM ERN
   LS THROUGH SRN QUEBEC THIS FORECAST PERIOD.  THE TRAILING COLD FRONT
   WILL SPREAD ESEWD ACROSS THE UPPER MS VALLEY...GREAT LAKES REGION...
   AND SRN ONTARIO/QUEBEC.  THE SWRN EXTENT OF THIS BOUNDARY WILL MOVE
   SWD THROUGH IA...CENTRAL KS TO A SURFACE LOW OVER SWRN KS/OK
   PANHANDLE.  THE WRN PORTION OF THE COLD FRONT IS EXPECTED TO EXTEND
   NWWD FROM THE SRN PLAINS LOW ACROSS THE FRONT RANGE OF CO/WY. IN THE
   NORTHWEST...A COLD FRONT ATTENDANT TO THE SEWD MOVING TROUGH WILL
   ADVANCE E/SEWD ACROSS THE INTERMOUNTAIN WEST AND SHOULD EXTEND FROM
   THE NRN ROCKIES INTO THE NRN GREAT BASIN BY 12Z THURSDAY.
   
   ...GREAT LAKES TO IA/NRN MO SWWD TO CENTRAL PLAINS...
   THE STRONGEST HEIGHT FALLS/FORCING IS EXPECTED TO REMAIN ACROSS
   ONTARIO INTO CENTRAL QUEBEC THIS FORECAST PERIOD WITH WEAK HEIGHT
   FALLS GLANCING UPPER MI AND NRN LOWER MI.  DESPITE OVERALL WEAK
   FORCING ALOFT FOR ASCENT ACROSS THIS PART OF THE SLIGHT RISK
   AREA...THE PRE-COLD FRONTAL ENVIRONMENT IS EXPECTED TO BECOME
   MODERATELY TO STRONGLY UNSTABLE /MLCAPE 2000-3500 J PER KG/ BY THIS
   AFTERNOON.
   
   STORMS ARE FORECAST TO DEVELOP BY MID TO LATE AFTERNOON ACROSS WI
   INTO UPPER AND NRN LOWER MI AHEAD OF THE ADVANCING COLD FRONT. 
   ACTIVITY WILL THEN FORM SWWD ALONG THE FRONT INTO KS...WITH A STORM
   OR TWO POSSIBLY INITIATING AS FAR S AS WRN OK/NWRN TX.  SHEAR ACROSS
   THIS REGION WILL BE FAVORABLE FOR MAINLY MULTICELLS...THOUGH
   SUPERCELL STORMS WILL BE POSSIBLE WITH NWD EXTENT ACROSS THE WRN
   GREAT LAKES WHERE EFFECTIVE BULK SHEAR WILL BE STRONGER.  LARGE
   HAIL...SOME VERY LARGE...AND DAMAGING WINDS WILL BE POSSIBLE WITH
   STRONGER STORMS.  AN ISOLATED TORNADO POTENTIAL WILL EXIST...MAINLY
   OVER THE WRN GREAT LAKES WHERE A SECONDARY AREA OF LOW PRESSURE WILL
   ENHANCE LOW LEVEL CONVERGENCE/SHEAR AS IT SHIFTS SSEWD WITH THE COLD
   FRONT FROM UPPER MI THROUGH WI INTO THE MIDWEST TONIGHT.
   
   TONIGHT...A LLJ INCREASING ACROSS THE PLAINS WILL SUPPORT ELEVATED
   CONVECTION N OF THE SURFACE FRONT...WITH THE POTENTIAL FOR LARGE
   HAIL ACROSS MAINLY NEB.
   
   ...CENTRAL HIGH PLAINS...
   THE PRESENCE OF STEEP MIDLEVEL LAPSE RATES AND STRONG SURFACE
   HEATING ALONG THE FRONT RANGE OF NERN CO/SERN WY TODAY COMBINED WITH
   POST-FRONTAL UPSLOPE FLOW AND SWLY FLOW ALOFT WILL RESULT IN AN
   ENVIRONMENT FAVORABLE FOR TSTM DEVELOPMENT...WITH SUPERCELLS LIKELY.
   ALTHOUGH INSTABILITY WILL BE MARGINAL /MLCAPE AOB 500 J PER
   KG/...DUE TO LIMITED MOISTURE...MODELS AGREE THAT OVERALL TSTM
   COVERAGE WILL BE SUFFICIENT TO MAINTAIN A SLIGHT RISK OF SEVERE
   STORMS.  ELY LOW LEVEL WINDS AND SUBSEQUENT WAA REGIME ARE EXPECTED
   TO STRENGTHEN ACROSS WRN NEB THIS EVENING SUGGESTING STORMS MOVING
   OFF THE HIGHER TERRAIN MAY GROW UPSCALE IN AN MCS WITH HAIL BECOMING
   THE PRIMARY THREAT AFTER DARK.
   
   ...NERN PA/ERN NY INTO NRN NEW ENGLAND...
   A WARM FRONT EXTENDING SWD FROM THE LEAD SURFACE LOW MOVING THROUGH
   SRN ONTARIO/QUEBEC TODAY WILL ADVANCE CONCURRENTLY EWD AND SHOULD
   REACH WRN NEW ENGLAND BY MID-LATE AFTERNOON.  SOME STRENGTHENING OF
   WLY LOW LEVEL WINDS ACROSS THE WARM SECTOR WILL SUPPORT MOISTURE
   RETURN INTO THE NERN STATES SLIGHT RISK AREA WITH SURFACE DEWPOINTS
   IN THE MID-UPPER 60S EXPECTED BY AFTERNOON.  SURFACE HEATING IN THE
   WAKE OF ONGOING MORNING CONVECTION ACROSS PARTS OF NY COMBINED WITH
   THE INCREASING MOISTURE AND PRESENCE OF STEEP MIDLEVEL LAPSE RATES
   WILL RESULT IN MODERATE TO VERY STRONG INSTABILITY /MLCAPE 2000-3000
   J PER KG/.  DESPITE WEAK TO NEUTRAL HEIGHT RISES...MODELS SUGGEST A
   WEAK IMPULSE OR TWO MOVING ACROSS THE STRONGLY UNSTABLE AIR MASS
   WILL SUPPORT TSTM DEVELOPMENT FROM ERN NY/NERN PA INTO WRN NEW
   ENGLAND.  EFFECTIVE BULK SHEAR OF 25-30 KT WILL TEND TO SUPPORT
   MULTICELLS WITH HAIL/DAMAGING WINDS THE PRIMARY THREATS.  THE
   PRESENCE OF STEEP MIDLEVEL LAPSE RATES AND DEGREE OF INSTABILITY
   SUGGEST SOME OF THE HAIL COULD BE VERY LARGE.  AN ISOLATED TORNADO
   CANNOT BE RULED OUT...GIVEN VERTICALLY VEERING WIND PROFILES WITH
   LOW LEVEL SHEAR STRENGTHENING FROM NY INTO MAINE AS A WLY LLJ
   INCREASES DURING THE AFTERNOON/EVENING.
   
   THE SEVERE WEATHER THREAT ACROSS NRN NEW ENGLAND WILL MAINLY BE
   ASSOCIATED WITH ONE OR MORE CLUSTERS OF STORMS SPREADING ESEWD INTO
   THAT AREA FROM CANADA.  MODERATE INSTABILITY AND STRONGER DEEP LAYER
   SHEAR WITH NEWD EXTENT SHOULD PROVE FAVORABLE FOR A GREATER
   POTENTIAL FOR SUPERCELLS.
   
   ..PETERS/COHEN.. 06/08/2011
   
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