MESOSCALE DISCUSSION 0690
   NWS STORM PREDICTION CENTER NORMAN OK
   0849 PM CDT FRI MAY 04 2007
   
   AREAS AFFECTED...NERN NEB AND SERN SD
   
   CONCERNING...TORNADO WATCH 226...
   
   VALID 050149Z - 050245Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 226 CONTINUES.
   
   A COUPLE SUPERCELL TSTMS HAVE BEEN PERSISTENT ACROSS SERN SD THIS
   EVENING...WITH THE STRONGEST CELL EXHIBITING LOW-LEVEL ROTATION
   MOVING INTO SERN MINER COUNTY.  MESOANALYSIS PLACES A WARM FRONT
   ALONG THE MO RVR VLY NWWD TO JUST WEST OF KFSD WITH THE
   AFOREMENTIONED SUPERCELL PROBABLY INTERACTING WITH THIS BAROCLINIC
   ZONE.
   
   LARGE SCALE SUPPORT SEEMS TO BE TIED WITH A LEAD IMPULSE MIGRATING
   NWD THROUGH THE PLAINS.  LARGE CANOPY OF PCPN OVER SD HAS MITIGATED
   DESTABILIZATION NWWD INTO THE BODY OF SD...BUT A NARROW WEDGE OF
   LOW-LEVEL MOISTURE AND WARM TEMPERATURES CONTINUES TO BE LOCATED
   OVER SERN SD.  AS THE LLJ AXIS...ASSOCD WITH THE IMPULSE...
   TRANSLATES NWD...MOST OF THE WARM ADVECTION WILL GO INTO SUPPORTING
   MOSTLY ELEVATED STORMS ACROSS THE CNTRL/ERN DAKS.  HOWEVER...THERE
   WILL CONTINUE TO BE AT LEAST A MARGINAL THREAT FOR DAMAGING
   WINDS...HAIL AND ISOLD TORNADOES WITHIN THE INSTABILITY AXIS ACROSS
   SERN SD FOR A FEW MORE HOURS.  THUS...ANOTHER SMALL WW MAY BE
   REQUIRED TO COVER THAT SITUATION.
   
   OTHERWISE...FARTHER S IN NEB...THERE WILL LIKELY BE A BREAK IN THE
   SVR THREAT THROUGH LATE EVENING.  BUT...LATER TONIGHT...TSTMS
   DEVELOPING IN NCNTRL KS MAY DEVELOP/MOVE ENEWD TOWARD
   NEB...PRIMARILY IN AREAS ALREADY COVERED IN TORNADO WATCH 229.
   
   ..RACY.. 05/05/2007
   
   
   ATTN...WFO...FSD...OAX...ABR...
   
   43239908 44379850 44899834 44789732 44019760 42679672
   41889730 41759804 43009819