June 21: Mesoscale Discussion- South Half of WI, North Half of IL, East IA, Southeast MN

Begin SPC Discussion

MESOSCALE DISCUSSION 1337
   NWS STORM PREDICTION CENTER NORMAN OK
   1145 AM CDT TUE JUN 21 2011
   
   AREAS AFFECTED...SERN MN...ERN IA...MUCH OF SRN WI...CNTRL AND NRN
   IL
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 211645Z - 211915Z
   
   A GENERAL INCREASE IN CONVECTIVE COVERAGE IS EXPECTED THIS
   AFTERNOON...AND A WATCH MAY EVENTUALLY BE NEEDED.
   
   SURFACE ANALYSIS SHOWS A LOW OVER WRN IA...WITH A BROADLY CONFLUENT
   WARM SECTOR WITH THETA-E AXIS FROM SERN MN INTO NRN IL. MORNING
   SOUNDINGS SHOWED EFFECTS OF EARLY CONVECTION WITH SOMEWHAT DRY JUST
   ABOVE THE SURFACE TO ABOUT 850 MB.
   
   AREAS OF HEATING...ALONG WITH GENERALLY CONVERGENT LOW
   LEVELS...SHOULD RESULT IN AN ARC OF CONVECTION THIS AFTERNOON.OTHER
   STORMS ARE LIKELY TO GENERATE/STRENGTHEN NEAR THE WARM FRONT. WIND
   PROFILES VEER WITH HEIGHT BUT ARE GENERALLY MARGINAL...YET
   SUFFICIENT FOR SUPERCELLS. MARGINAL HAIL WITH RELATIVELY WARM MID
   LEVELS...AND A FEW TORNADOES GIVEN SUFFICIENT LOW LEVEL SHEAR...WILL
   BE POSSIBLE. A FEW NWD MOVING BOWS MAY MATERIALIZE WITH TIME WITH
   DAMAGING WIND THREAT.

End SPC Discussion

Begin The Weather Centre Discussion

Strong low is moving into vicinity with warm front pulling into Wisconsin. Warm sector has pulled  up into the area below warm front.

Do expect scattered convection to become organized into bowing sectors and possibly clusters that may be supportive of supercell activity.