Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 070551
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1251 AM CDT THU JUN 07 2007
   
   VALID 071200Z - 081200Z
   
   ...THERE IS A HIGH RISK OF SVR TSTMS TODAY ACROSS PARTS OF THE UPPER
   MISSISSIPPI VALLEY/GREAT LAKES REGION...INCLUDING  PARTS OF ERN
   MN...MUCH OF NRN/CENTRAL WI...AND THE UPPER PEN OF  MICHIGAN....
   
   ...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK
   AREA...ACROSS MUCH OF THE REMAINDER OF THE MID/UPPER MISSISSIPPI
   VALLEY AND GREAT LAKES REGION....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS TODAY/TONIGHT...EXTENDING
   SOUTHWEST OF THE MIDDLE MISSISSIPPI VALLEY INTO THE SOUTHERN
   PLAINS....
   
   ...SYNOPSIS...
   A SIGNIFICANT SHORT WAVE TROUGH...DIGGING TO THE SOUTH OF
   RETROGRADING CLOSED LOW OVER NORTH CENTRAL CANADA...IS PROGGED TO
   CONTINUE SOUTHEASTWARD TOWARD THE CENTRAL CANADIAN/U.S. BORDER AREA
   TODAY.  AS THIS OCCURS...MODELS INDICATE THAT A SIGNIFICANT CLOSED
   LOW AND ASSOCIATED SHORT WAVE IMPULSE...NOW LIFTING INTO THE NORTH
   CENTRAL PLAINS...WILL CONTINUE TO ACCELERATE NORTHEASTWARD INTO THE
   UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES REGION.  PHASING OF THE
   TWO SYSTEMS IS PROGGED TO OCCUR LATER TODAY/TONIGHT...LEADING TO A
   RE-INTENSIFICATION OF LOW/MID-LEVEL FLOW FIELDS NEAR A DEEP
   CYCLONE...WHICH IS PROGGED TO TRACK FROM THE EASTERN DAKOTAS THROUGH
   NORTHEAST MINNESOTA BY LATE THIS AFTERNOON...INTO ONTARIO TONIGHT.
   
   SURFACE FRONT TRAILING FROM THE SURFACE LOW WILL SURGE THROUGH THE
   UPPER MIDWEST...WHILE PROGRESSING MORE SLOWLY THROUGH THE MIDDLE
   MISSISSIPPI VALLEY/SOUTH CENTRAL PLAINS.  UPPER RIDGING WILL REMAIN
   STRONG ACROSS THE ATLANTIC SEABOARD AND THE SOUTH CENTRAL
   /SOUTHEASTERN STATES...BUT ANOTHER IMPULSE LIFTING OUT OF THE
   BROADER SCALE WESTERN TROUGH IS EXPECTED TO SHIFT NORTHEAST OF THE
   CENTRAL/SOUTHERN ROCKIES BY EARLY THIS EVENING.
   
   ...MID/UPPER MISSISSIPPI VALLEY AND UPPER GREAT LAKES...
   MODELS ARE SUGGESTIVE THAT A MID-LEVEL DRY SLOT WILL NOSE
   NORTHEASTWARD THROUGH THE UPPER MISSISSIPPI VALLEY BY MID
   DAY...ALLOWING FOR HEATING OF MOISTENING BOUNDARY LAYER IN WARM
   SECTOR OF SURFACE CYCLONE.  SURFACE DEW POINTS APPEAR LIKELY TO
   CLIMB AT LEAST THROUGH THE LOWER/MID 60S THROUGH MUCH OF THE UPPER
   MISSISSIPPI VALLEY...WITH MIXED LAYER CAPE EXCEEDING 1000 J/KG...
   AND POSSIBLY LOCALLY APPROACHING 2000 J/KG.  
   
   THOUGH DESTABILIZATION IS NOT EXPECTED AS STRONG AS AREAS UNAFFECTED
   BY EARLY MORNING CONVECTION TO THE SOUTH...INSTABILITY SHOULD BE
   SUFFICIENT FOR VIGOROUS CONVECTIVE DEVELOPMENT ACROSS EASTERN
   MINNESOTA/NORTHWEST WISCONSIN BY EARLY THIS AFTERNOON.  MODELS
   SUGGEST THIS WILL OCCUR IN RESPONSE TO FORCING IN THE EXIT REGION OF
   A 90+ KT 500 MB JET STREAK.  GIVEN THE MAGNITUDE OF THE DEEP LAYER
   SHEAR...AND THE LIKELIHOOD OF LARGE LOW-LEVEL HODOGRAPHS BENEATH
   40-50 KT SOUTHERLY 850 MB FLOW...PLUS FAVORABLE AMBIENT VERTICAL
   VORTICITY ASSOCIATED WITH LOW/MID-LEVEL CYCLONE...POTENTIAL FOR
   TORNADIC SUPERCELLS SEEMS HIGH.  A FEW STRONG TORNADOES ARE POSSIBLE
   AS CONVECTIVE ACTIVITY DEVELOPS NORTHEASTWARD ACROSS NORTH CENTRAL
   WISCONSIN INTO UPPER MICHIGAN ...AND PARTS OF NORTHEASTERN MINNESOTA
   NOT AFFECTED BY COLD BOUNDARY LAYER OFF LAKE SUPERIOR.
   
   FARTHER SOUTH...MID-LEVEL INHIBITION GENERALLY SEEMS LIKELY TO LIMIT
   CONVECTIVE DEVELOPMENT TO THE VICINITY OF SURFACE FRONT ACROSS PARTS
   OF EASTERN IOWA/NORTHWESTERN ILLINOIS INTO NORTHEAST MISSOURI BY
   LATE THIS AFTERNOON.  BUT...MODERATE TO STRONGLY UNSTABLE
   PRE-FRONTAL ENVIRONMENT IS EXPECTED TO SUPPORT RAPID EVOLUTION OF A
   SEVERE SQUALL LINE WITH FRONTAL FORCING...IN STRONG FLOW/SHEAR
   ENVIRONMENT.  ACTIVITY IS EXPECTED TO ACCELERATE NORTHEASTWARD
   TOWARD THE GREAT LAKES REGION MORE QUICKLY THAN EASTWARD INTO THE
   LOWER OHIO VALLEY...ACCOMPANIED BY HIGH WINDS AND HAIL.  SOME OF THE
   WIND GUSTS COULD BECOME QUITE STRONG...WITH THE ADDITIONAL RISK FOR
   ISOLATED TORNADOES IN SUPERCELLS EMBEDDED WITHIN THE LINE. 
   AND...THE SEVERE THREAT MAY PERSIST WELL INTO THE EVENING OR
   OVERNIGHT HOURS...BEFORE GRADUALLY DIMINISHING ACROSS THE GREAT
   LAKES/OHIO VALLEY REGION LATE TONIGHT.
   
   ...OZARK PLATEAU INTO SOUTHERN PLAINS...
   UNCERTAINTY EXISTS ON TIMING OF CONVECTIVE DEVELOPMENT...BUT MIDDLE
   MISSISSIPPI VALLEY SQUALL LINE MAY EVENTUALLY BUILD SOUTHWESTWARD
   TOWARD THE SOUTHERN PLAINS RED RIVER VALLEY BY TONIGHT...AS
   MID-LEVEL INHIBITION SLOWLY WEAKENS.  DEEP LAYER SHEAR AND
   INSTABILITY WILL BE SUFFICIENT FOR AT LEAST A RISK OF HAIL IN
   STRONGER STORMS.  STRONG GUSTY WINDS ARE ALSO POSSIBLE...BUT
   TENDENCY MAY BE FOR STORMS TO BE UNDERCUT OR FORM TO THE NORTH OF
   SURFACE COLD FRONT...LIMITING DAMAGING WIND POTENTIAL.
   
   ..KERR/TAYLOR.. 06/07/2007
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z