SPC AC 070559

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1259 AM CDT SUN JUN 07 2015

   VALID 071200Z - 081200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS TODAY INTO THIS EVENING ACROSS
   PARTS OF NORTHERN AND CENTRAL ILLINOIS...NORTHERN AND CENTRAL
   INDIANA...AND EXTREME SOUTHWEST LOWER MICHIGAN...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ENH RISK AREA
   ACROSS THE SOUTHERN GREAT LAKES AND OH VALLEY THROUGH THE LOWER MO
   VALLEY TO PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS...

   ...THERE IS A MRGL RISK OF SVR TSTMS EXTENDING FROM THE GREAT LAKES
   AND OH VALLEY TO THE CENTRAL AND SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   SEVERE THUNDERSTORMS WILL BE POSSIBLE TODAY FROM PARTS OF THE LOWER
   GREAT LAKES AND OHIO VALLEY REGION TO THE CENTRAL AND SOUTHERN HIGH
   PLAINS...WITH THE GREATEST POTENTIAL ACROSS NORTHERN AND CENTRAL
   PORTIONS OF ILLINOIS AND INDIANA...AND FAR SOUTHWEST LOWER MICHIGAN.

   ...SYNOPSIS...
   A MIDLEVEL SPEED MAX WILL CROSS PORTIONS OF THE MIDDLE/UPPER MS
   VALLEY AND GREAT LAKES REGION ON THE SOUTH SIDE OF A
   BROAD/AMPLIFYING TROUGH ACROSS THE UPPER/MIDDLE MS VALLEY AND GREAT
   LAKES REGION.  A RELATED SURFACE LOW WILL ADVANCE ACROSS PARTS OF
   NRN WI AND UPPER MI INTO ADJACENT ONTARIO...REACHING SWRN QUEBEC BY
   12Z MONDAY.  A COLD FRONT EXTENDING SW OF THE SURFACE LOW TO THE CO
   ROCKIES FRONT RANGE WILL ADVANCE EAST AND SOUTH TOWARD LOWER
   MI...INTO THE MIDWEST...LOWER MO VALLEY AND THROUGH THE CENTRAL
   PLAINS.  THE LEADING EDGE OF THE WARM SECTOR WILL ADVANCE NNEWD
   ACROSS SRN AND ERN PORTIONS OF THE GREAT LAKES REGION...ESTABLISHING
   A BROAD CORRIDOR OF RICH GULF RETURN MOISTURE AHEAD OF THE COLD
   FRONT.  MEANWHILE...A MIDLEVEL TROUGH WILL ELONGATE ENE/WSW OVER
   PARTS OF THE GREAT BASIN TO CENTRAL ROCKIES...BETWEEN FLANKING
   RIDGES OVER THE SRN PLAINS AND NWRN STATES.

   ...SRN GREAT LAKES/OH AND MID MS VALLEYS...
   AN ONGOING MCS...POSSIBLY PRODUCING STRONG TO SEVERE STORMS...SHOULD
   BE MOVING THROUGH ERN WI...FAR NRN IL AND WEST-CENTRAL IL PER RECENT
   HRRR RUNS/00Z NAM/12Z ECMWF.  MODERATE-STRONG INSTABILITY IS
   EXPECTED ACROSS THE WARM SECTOR...GIVEN LOW-LEVEL MOISTENING
   /SURFACE DEW POINTS IN THE MID-UPPER 60S/ AS FAR EAST AS SRN LOWER
   MI AND WRN OH AND DIABATIC HEATING.  THE LEADING EXTENT OF THE EARLY
   MORNING MCS SHOULD RE-INTENSIFY IT REACHES SWRN LOWER MI AND NRN IL
   /INCLUDING THE CHICAGO METRO AREA/ BY EARLY AFTERNOON.  EFFECTIVE
   BULK SHEAR OF 30-35 KT ORIENTED GENERALLY PARALLEL TO THE CONVECTIVE
   OUTFLOW BOUNDARY SUGGESTS LINE SEGMENTS/BOWING STRUCTURES AS THE
   PRIMARY STORM MODE WITH DAMAGING WINDS THE PRIMARY THREAT. 
   HOWEVER...ENHANCED LOW-LEVEL SHEAR ALONG MODESTLY STRONG SWLY
   LOW-LEVEL WINDS WILL FAVOR A TORNADO THREAT.  

   THE POTENTIAL EXISTS FOR AFTERNOON STORMS TO CONGEAL INTO A
   WSW/ENE-ELONGATED QUASI-LINEAR MCS THROUGH THE EARLY EVENING HOURS. 
   THIS ACTIVITY SHOULD BE LARGELY ORIENTED PARALLEL TO THE MEAN
   CLOUD-LAYER FLOW...WHILE GRADUALLY SPREADING ESEWD/SEWD INTO PARTS
   OF CENTRAL IL...CENTRAL INDIANA...NWRN OH...SERN IL AND PARTS OF WRN
   OH.  DAMAGING WINDS AND MARGINALLY SEVERE HAIL WILL REMAIN POSSIBLE
   WITH THIS ACTIVITY AS CONVECTION REGENERATES/SPREADS INTO A
   MOIST/MODERATELY UNSTABLE AIR MASS.

   ...PORTIONS OF NRN/CENTRAL MO WWD TO ERN CO...
   ASCENT SUPPORTING CONVECTION WILL BE PRIMARILY CONFINED TO LOW-LEVEL
   CONVERGENCE PROCESSES RELATED TO THE COLD FRONT AND THE TRAILING
   EXTENT OF THE OUTFLOW BOUNDARY ATTENDANT TO THE WI/NRN IL MCS AS IT
   SETTLES SWD.  ISOLATED TO WIDELY SCATTERED TSTMS WILL LIKELY DEVELOP
   NEAR THESE BOUNDARIES AND WWD TO DIURNALLY ENHANCED OROGRAPHIC
   CIRCULATIONS OVER THE CO FRONT RANGE AND MOIST/UPSLOPE FLOW TO ITS
   E. THE PRESENCE OF 25-35 KT OF DEEP SHEAR WILL HAVE THE POTENTIAL TO
   SUPPORT ORGANIZED/SUSTAINED CONVECTIVE STRUCTURES/POSSIBLE
   SUPERCELLS.  IN THE ABSENCE OF A STRONG EQUATORWARD SURGE OF LOW
   THETA-E AIR...CONVECTION SHOULD ALSO EVOLVE BEHIND THE COLD FRONT IN
   PARTS OF E-CNTRL CO INTO NRN KS AND PERHAPS FAR SRN NEB WHERE
   POST-FRONTAL DIRECTIONAL-FLOW VARIABILITY IN THE LOW-LEVELS WILL
   BOLSTER DEEP SHEAR /POTENTIAL FOR ORGANIZED STORMS/.  A
   STRENGTHENING SWLY LLJ FROM OK INTO SERN KS AND MO MAY AID IN
   SUSTAINING TSTMS THROUGH THE EVENING INTO THE EARLY OVERNIGHT PERIOD
   ACROSS SERN KS TO CENTRAL MO WITH A LINGERING THREAT FOR STRONG TO
   SEVERE STORMS.

   ..PETERS/DEAN.. 06/07/2015

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