MESOSCALE DISCUSSION 1571
   NWS STORM PREDICTION CENTER NORMAN OK
   0507 AM CDT MON JUL 11 2011
   
   AREAS AFFECTED...PORTIONS ERN/SRN WI...ERN IA...NRN IL...CENTRAL/SRN
   LM...W-CENTRAL/SWRN LOWER MI.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 623...624...
   
   VALID 111007Z - 111200Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   623...624...CONTINUES.
   
   ADDITIONAL WW ISSUANCE(S) MAY BE NEEDED E OF CURRENT WWS FROM LOWER
   MI TO NRN IL.  TWO PRIMARY MCS CLUSTERS AFFECT WW...
   
   1. MOST SIGNIFICANT THREAT WILL REMAIN DOWNSHEAR FROM
   SIGNIFICANT-WIND PRODUCING COMPLEX MOVING EWD TO ENEWD 50-55 KT OVER
   ERN IA.  MOST INTENSE PORTION OF THIS COMPLEX YIELDED ESTIMATES OF
   61-87 KT GUSTS OVER TAMA COUNTY IA AT 922Z... MEASURED 70 KT IN
   MARSHALL COUNTY AT 920Z...AND MEASURED 65 KT IN BENTON COUNTY IA AT
   949Z.  THESE WERE ONLY SLIGHTLY BELOW MID-RANGE OF VALUES NOTED IN
   BASE VELOCITY OUTPUT FROM 500-3000 FT AGL...AS ACTIVITY RETREATED
   NEWD AWAY FROM DMX RADAR UNIT.  OUTFLOW BOUNDARY FROM WI COMPLEX
   WILL ACT AS PRIMARY FOCUS FOR FORWARD PROPAGATION AND LIFT
   ASSOCIATED WITH THIS MCS...HELPING TO CHANNEL THREAT FOR SVR GUSTS
   TOWARD DBQ AREA AND WI/IL BORDER REGION.  PROSPECTIVE INFLOW-LAYER
   AIR MASS S OF OUTFLOW BOUNDARY WILL REMAIN RICHLY MOIST WITH SFC DEW
   POINTS 70S F...AMIDST 35-45 KT EFFECTIVE SHEAR VECTORS ALIGNED
   ORTHOGONALLY WITH RESPECT TO CONVECTIVE BAND.  STRENGTHENING CINH
   AND WEAKENING SHEAR WITH SWD EXTENT OVER NRN IL LEND MORE
   CONDITIONAL/UNCERTAIN THREAT S OF I-80 CORRIDOR...HOWEVER SVR TSTM
   WINDS MAY AFFECT DBQ/RFD/CHI AREAS IN THAT ORDER THROUGH MID-LATE
   MORNING.
   
   2. SQUALL LINE FROM GRB-MSN AS OF 930Z..MOVING ESEWD 40-45 KT TOWARD
   WRN/CENTRAL LM AND EVENTUALLY PORTIONS WRN LOWER MI.  CONVECTION
   CONTINUES TO MOVE EWD ALONG LOW-LEVEL BAROCLINIC ZONE AND RELATED
   THETAE GRADIENT...WITH POTENTIAL FOR OCNL DAMAGING GUSTS.  THIS
   ACTIVITY HAS PRODUCED A FEW DAMAGING GUSTS...INCLUDING ONE MEASURED
   SVR GUST OF 55 KT IN GREEN LAKE COUNTY WI AT 905Z.  POTENTIAL FOR
   INTERMITTENT WIND DAMAGE WILL CONTINUE WITH THIS ACTIVITY AS IT
   MOVES ACROSS LAKESHORE.  AIR MASS IS NEITHER AS UNSTABLE NOR AS
   CHARACTERIZED BY FAVORABLE DEEP-LAYER SHEAR E OF LM AS OVER WI. 
   HOWEVER...PRESENCE OF MATURE COLD POOL WITH FORWARD-PROPAGATIONAL
   SLAB OF ASCENT...ALONG WITH FAVORABLE LOW-LEVEL WAA/MOISTURE
   TRANSPORT JUST ABOVE SFC...SUGGEST COMPLEX MAY OFFER RISK OF WIND
   DAMAGE OVER PORTIONS LOWER MI AS WELL.  WW MAY BE REQUIRED THERE.
   
   ..EDWARDS.. 07/11/2011
   
   
   ATTN...WFO...APX...GRR...GRB...LOT...ILX...MKX...DVN...ARX...
   DMX...
   
   LAT...LON   41059231 42289266 43059173 43409074 43298932 43958818
               44518756 44248574 42748572 42798750 41788765 41238845
               40979009 40939091 41059231