MESOSCALE DISCUSSION 0949
   NWS STORM PREDICTION CENTER NORMAN OK
   1109 AM CDT FRI JUN 01 2007
   
   AREAS AFFECTED...PARTS OF NE MO INTO EXTREME ERN IA...W CNTRL/NW
   IL...SRN WI
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 011609Z - 011815Z
   
   TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT AND THE
   POSSIBILITY OF A WW...WHICH COULD BECOME NECESSARY EARLY THIS
   AFTERNOON.
   
   WEAKENING MID-LEVEL CYCLONIC VORTICITY CENTER/LOBE LIFTING NORTHEAST
   OF THE LOWER MISSOURI VALLEY IS PROVIDING THE PRIMARY FORCING FOR
   ARCING BAND OF CONVECTION NOW SPREADING THROUGH EASTERN IOWA. 
   ACTIVITY APPEARS MOSTLY BASED IN ELEVATED ZONE OF ISENTROPIC
   ASCENT...ABOVE THE BOUNDARY LAYER.  AND...NORTHEASTERLY LOW-LEVEL
   STORM RELATIVE INFLOW...EMANATING FROM DRIER ENVIRONMENT APPEARS TO
   BE CONTRIBUTING TO CURRENT WEAKENING TRENDS.
   
   HOWEVER...AHEAD OF TRAILING SURFACE WIND SHIFT/REMNANT OUTFLOW
   BOUNDARY...A MOIST BOUNDARY LAYER WITH MID 60S SURFACE DEW POINTS IS
   BEGINNING TO DESTABILIZE WITH DAYTIME HEATING ACROSS MUCH OF EASTERN
   MISSOURI AND WESTERN ILLINOIS.  AS INHIBITION WEAKENS...MIXED LAYER
   CAPE APPROACHING 2000 J/KG SEEMS POSSIBLE BY MID AFTERNOON. 
   AND...FORCING ASSOCIATED WITH UPPER IMPULSE IS EXPECTED TO BE
   SUFFICIENT TO SUPPORT INCREASING/INTENSIFYING CONVECTIVE DEVELOPMENT
   ALONG SURFACE BOUNDARY.  A SEASONABLY STRONG BELT OF FLOW ASSOCIATED
   WITH 50+ KT 500 MB JET STREAK WILL ENHANCE STORM MOTIONS AND SHEAR
   PROFILES...CONTRIBUTING TO AN ORGANIZING LINE OF STORMS WITH WIND
   DAMAGE/HAIL POTENTIAL.  ISOLATED SUPERCELLS WILL BE POSSIBLE WITHIN
   AND JUST AHEAD OF LINE ...PARTICULARLY IN STRONGEST LOW-LEVEL WARM
   ADVECTION REGIME...LIKELY SOUTHWEST THROUGH SOUTH OF BURLINGTON IA
   BY 18-19Z.  THIS IS WHERE LOW-LEVEL HODOGRAPHS WILL BECOME ENHANCED
   AND SUPPORTIVE OF A RISK FOR ISOLATED TORNADOES.
   
   ..KERR.. 06/01/2007
   
   
   ATTN...WFO...LOT...ILX...MKX...LSX...DVN...ARX...DMX...
   
   40449197 41529254 42259259 42899117 42849010 42308920
   40928887 39728936 39139069 39249191