Mesoscale Discussion #1708

Terms to know:
*Synoptic Front: A front. Example: cold/warm front.
*Deep Layer Shear: Winds moving in different directions and at different speeds.
*Forcing: A mechanism that usually enables warm air to rise, which creates thunderstorms.
*

MESOSCALE DISCUSSION 1708
   NWS STORM PREDICTION CENTER NORMAN OK
   0152 PM CDT SAT JUL 23 2011
   
   AREAS AFFECTED...FAR ERN SD...MUCH OF CENTRAL AND SRN MN AND FAR NRN
   IA.
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 231852Z - 232015Z
   
   STORMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY ACROSS
   PORTIONS OF CENTRAL/SRN MN THROUGH THE AFTERNOON...AND ALSO POSSIBLY
   DEVELOPING WWD INTO ERN SD AND SWD INTO NRN IA. A WW LIKELY WILL BE
   NEEDED IN THE NEXT HOUR OR SO FOR PORTIONS OF THIS AREA.
   
   ELEVATED STORMS HAD RECENTLY DEVELOPED IN AN E-W BAND ACROSS WEST
   CENTRAL MN...NORTH OF A STC-VVV LINE. THESE STORMS WERE LOCATED
   AHEAD OF THE SEWD MOVING SYNOPTIC FRONT...THAT EXTENDED FROM NWRN MN
   SEWD INTO ERN SD. SUFFICIENT DEEP LAYER SHEAR AND INSTABILITY EXISTS
   FOR MARGINALLY SEVERE HAIL WITH THESE STORMS THE NEXT HOUR OR TWO. 
   
   HOWEVER...WITH ADDITIONAL HEATING/BOUNDARY LAYER DESTABILIZATION AND
   STRONGER LARGE SCALE FORCING SPREADING IN FROM THE WEST... MORE
   STORMS ARE FORECAST TO DEVELOP AND BECOME SURFACE BASED. ONCE THIS
   HAPPENS...EFFECTIVE SHEAR AT 40-50 KT AND MODERATE INSTABILITY WILL
   BE FAVORABLE FOR SUPERCELLS. WHILE SEVERE HAIL/WINDS SHOULD BE THE
   PRIMARY THREATS...THE VERY MOIST BOUNDARY LAYER AND THE FORECAST OF
   STRONGLY VEERING LOW LEVEL WIND PROFILES WOULD SUPPORT A TORNADO OR
   TWO. BY LATE AFTERNOON...HIGH RESOLUTION AND OPERATIONAL MODELS ARE
   IN AGREEMENT OF STORMS CONGEALING INTO A SEWD MOVING LINEAR MCS...
   WITH WIND DAMAGE BECOMING THE PRIMARY THREAT AT THAT TIME.