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

   SPC AC 081251
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0751 AM CDT SUN JUN 08 2008
   
   VALID 081300Z - 091200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS TODAY INTO EARLY TONIGHT FROM
   THE SRN HIGH PLAINS TO THE GREAT LAKES...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
   UPSTATE NY AND NRN VT...
   
   ...SYNOPSIS...
   A CLOSED MID LEVEL LOW OVER NE MT/NW ND...AND A TROUGH TRAILING
   SSWWD OVER WY AND UT...WILL MOVE EWD ACROSS THE CENTRAL/NRN PLAINS
   TOWARD THE UPPER MS VALLEY BY 09/12Z.  A REMNANT LEE CYCLONE NOW
   OVER NRN KS WILL MOVE NEWD ACROSS IA TODAY AND WI/UPPER MI TONIGHT
   IN ADVANCE OF THE MID LEVEL TROUGH.  IN THE WAKE OF THE SURFACE
   CYCLONE...A COLD FRONT WILL MOVE SEWD ACROSS IA/MO/KS TO NW OK AND
   THE NRN TX PANHANDLE.  THE COLD FRONT WILL BE PRECEDED BY A
   SECONDARY LEE CYCLONE WHICH WILL DEVELOP SLOWLY SWD ACROSS THE NW TX
   PANHANDLE.
   
   A BROAD SWATH OF RICH BOUNDARY LAYER MOISTURE /DEWPOINTS OF 68-72 F/
   EXTENDS NWD ACROSS THE GULF COAST TO THE SRN PLAINS/MS VALLEY...AND
   NEWD TO THE OH VALLEY.  RELATIVELY STEEP MID LEVEL LAPSE RATES ARE
   OVERSPREADING THE MOIST BOUNDARY LAYER FROM THE SRN PLAINS TO THE
   MID MS VALLEY...AND DAYTIME HEATING WILL CONTRIBUTE TO AFTERNOON
   MLCAPE VALUES OF 2500-3500 J/KG.  OVERNIGHT CONVECTION HAS PRODUCED
   MULTIPLE OUTFLOW BOUNDARIES ALONG AND S OF THE SYNOPTIC FRONT FROM
   LOWER MI/NRN INDIANA WWD ACROSS NRN IL TO IA.  THESE RESIDUAL
   BOUNDARIES WILL HELP FOCUS THUNDERSTORM DEVELOPMENT TODAY...ALONG
   WITH THE SYNOPTIC FRONT ACROSS THE CENTRAL/SRN PLAINS.
   
   ...ERN IA TO LOWER MI...
   WIDESPREAD OVERNIGHT CONVECTION HAS STABILIZED THE NW HALF OF
   IA...SE MN AND MUCH OF WI/LOWER MI.  THE OUTFLOW BOUNDARY MAY
   RETREAT NWD AND ALLOW STRONGER DESTABILIZATION ACROSS NRN IL/SRN WI
   AND SRN LOWER MI...GIVEN THE RELATIVE LACK OF STORMS N OF THE
   BOUNDARY NOW.  AREAS FARTHER N ARE UNLIKELY TO DESTABILIZE TO THE
   DEGREE SUGGESTED BY RECENT MODEL FORECASTS.  RICH MOISTURE ALONG AND
   S OF THE BOUNDARY WILL CONTRIBUTE TO MODERATE-STRONG
   INSTABILITY...WHILE THE SERN FRINGE OF THE STRONGER MID LEVEL FLOW
   WILL COINCIDE WITH THE OUTFLOW BOUNDARIES.  THE NET RESULT WILL BE
   AN ENVIRONMENT FAVORABLE FOR BOTH BOWING SEGMENTS AND EMBEDDED
   SUPERCELLS.  A COUPLE OF TORNADOES MAY OCCUR ALONG THE RESIDUAL
   BOUNDARIES WHERE LOW-LEVEL SHEAR IS MAXIMIZED AND LCL HEIGHTS REMAIN
   LOW...THOUGH DAMAGING WINDS AND ISOLATED LARGE HAIL WILL BE THE MAIN
   THREATS.
   
   ...MO TO THE SRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT...
   THE SYNOPTIC FRONT IS EXPECTED TO PROVIDE THE PRIMARY FOCUS FOR
   THUNDERSTORM DEVELOPMENT BEGINNING EARLY THIS AFTERNOON AND
   CONTINUING INTO TONIGHT.  THERMODYNAMIC PROFILES WILL BE SIMILAR TO
   AREAS FARTHER NE...THOUGH MID LEVEL LAPSE RATES WILL BE A LITTLE
   STEEPER IN PROXIMITY TO THE ROCKIES...AND BOUNDARY LAYER
   TEMP-DEWPOINT SPREADS WILL BE SOMEWHAT LARGER.  VERTICAL SHEAR IS
   NOT EXPECTED TO BE PARTICULARLY STRONG IN THE WARM SECTOR...WITH
   PRIMARILY UNIDIRECTIONAL SHEAR ABOVE THE BOUNDARY LAYER...ORIENTED
   ROUGHLY PARALLEL TO THE FRONT.  AN EXCEPTION WILL BE ACROSS THE TX
   PANHANDLE WHERE LOW-LEVEL SHEAR WILL BE STRONGER NEAR THE FRONT AND
   TO THE ENE OF THE LEE CYCLONE.  THERE WILL BE SOME POTENTIAL FOR
   SUPERCELLS ACROSS THE TX PANHANDLE THIS AFTERNOON/EVENING... BUT THE
   PRIMARY CONVECTIVE MODE SHOULD TRANSITION RATHER QUICKLY TO AN
   EXTENSIVE NE-SW BAND.  A COUPLE OF TORNADOES COULD OCCUR EARLY IN
   THE CONVECTIVE EVOLUTION...THOUGH SCATTERED DAMAGING WINDS AND LARGE
   HAIL WILL BE THE MAIN THREATS LATE THIS AFTERNOON INTO TONIGHT.  THE
   SEVERE THREAT WILL BEGIN TO DIMINISH BY EARLY TONIGHT AS LOCALLY
   HEAVY RAINS BECOME THE PRIMARY THREAT.
   
   ...UPSTATE NY AND NRN VT THIS AFTERNOON...
   A MID LEVEL TROUGH OVER QUEBEC WILL MOVE EWD...WHILE A TRAILING COLD
   FRONT APPROACHES NRN NEW ENGLAND TONIGHT.  DEBRIS CLOUDS FROM
   OVERNIGHT CONVECTION TO THE W SHOULD CONTINUE TO DIMINISH...
   ALLOWING STRONG SURFACE HEATING BY MIDDAY.  THE WARMING BOUNDARY
   LAYER AND INCREASING MOISTURE FROM THE SW WILL RESULT IN AFTERNOON
   MLCAPE VALUES OF 1000-1500 J/KG ACROSS MUCH OF NY AND NEW ENGLAND
   /SW OF MAINE/.  HOWEVER...VERTICAL SHEAR WILL BE WEAK OVER SRN
   NY/NEW ENGLAND...AND MARGINALLY FAVORABLE FOR ORGANIZED SEVERE
   STORMS OVER NRN NEW ENGLAND.  WITH NO STRONG FOCUS FOR STORM
   DEVELOPMENT TODAY...THE GREATER PROBABILITY FOR STORMS WITH DAMAGING
   WINDS SHOULD REMAIN FARTHER N WHERE VERTICAL SHEAR IS STRONGER.
   
   ...NRN VA TO THE SRN APPALACHIANS THIS AFTERNOON...
   A REMNANT MCV OVER NRN VA...AS WELL AS SURFACE HEATING OVER THE
   HIGHER TERRAIN...SHOULD CONTRIBUTE TO AT LEAST WIDELY SCATTERED
   THUNDERSTORM DEVELOPMENT THIS AFTERNOON.  12Z SOUNDINGS FROM IAD AND
   RNK INDICATE THE POTENTIAL FOR STEEP LOW-LEVEL LAPSE RATES AND
   MLCAPE AOA 2000 J/KG...WHICH COULD SUPPORT A FEW STORMS WITH HYBRID
   MICROBURSTS AND MARGINALLY SEVERE HAIL THIS AFTERNOON.
   
   ..THOMPSON/SMITH.. 06/08/2008
   
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