MESOSCALE DISCUSSION 1909
   NWS STORM PREDICTION CENTER NORMAN OK
   1156 PM CDT THU SEP 06 2012
   
   AREAS AFFECTED...PORTIONS OF IA
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 070456Z - 070700Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...POTENTIAL FOR AT LEAST ISOLATED SEVERE HAIL AND PERHAPS
   DAMAGING WINDS WILL EXIST OVERNIGHT ACROSS PORTIONS OF
   IA...INCLUDING NORTHWEST-MUCH OF CENTRAL-SOUTHEAST IA. WHILE THE
   EXTENT/MAGNITUDE OF THE SEVERE POTENTIAL REMAINS
   UNCLEAR...DEVELOPMENTAL TRENDS ARE STILL BEING MONITORED FOR A
   POSSIBLE WATCH.
   
   DISCUSSION...UPDATING EARLIER MESOSCALE DISCUSSION 1908...TSTMS
   CONTINUE TO STEADILY INCREASE IN COVERAGE ACROSS NORTHWEST/CENTRAL
   PORTIONS OF IA EARLY IN THE OVERNIGHT. THESE TSTMS ARE OCCURRING TO
   THE NORTHEAST OF A SURFACE LOW WARM FRONT LOCATED ACROSS FAR EASTERN
   NEB/WESTERN IA. WHILE UPDRAFTS HAVE NOT BEEN PARTICULARLY
   ROBUST/SUSTAINED OVER THE PAST FEW HOURS...CURRENT CLUSTER ACROSS
   NORTH-CENTRAL IA HAS A HISTORY OF 1-1.75 INCH HAIL IN NORTHWEST
   IA...AND A SIMILAR THREAT WILL LIKELY CONTINUE OVER THE FEW HOURS AT
   LEAST ON A SPORADIC BASIS WITH AID OF A MODERATE LOW LEVEL JET
   /REFERENCE 30 KT PER OMAHA AND TOPEKA WSR-88D VWPS/.
   
   AS A WARM/MOIST INFLUX CONTINUES TO OCCUR NEAR/ABOVE THE
   SURFACE...ADDITIONAL STORM DEVELOPMENT/POSSIBLE INTENSIFICATION
   SHOULD OCCUR ACROSS IA.  WHILE SEVERE HAIL SHOULD BE THE PRIMARY
   HAZARD AS THE BOUNDARY LAYER IS RELATIVELY STABLE...POTENTIAL FOR
   EVENTUAL UPSCALE GROWTH/CONTINUALLY STRENGTHENING WESTERLY MEAN FLOW
   SUGGESTS THAT SOME DAMAGING WIND THREAT CANNOT BE ENTIRELY
   DISCOUNTED OVERNIGHT.
   
   ..GUYER/HART.. 09/07/2012
   
   
   ATTN...WFO...DVN...DMX...FSD...OAX...
   
   LAT...LON   42119579 43269588 43179368 42429215 41209191 40909304
               41519502 42119579