MESOSCALE DISCUSSION 0247
   NWS STORM PREDICTION CENTER NORMAN OK
   0225 PM CDT TUE MAR 22 2011
   
   AREAS AFFECTED...NERN SD/SERN ND/W-CNTRL MN
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 221925Z - 222330Z
   
   A MIX OF WINTRY PRECIPITATION TYPES IS EXPECTED TO OVERSPREAD NERN
   SD...SERN ND...AND W-CNTRL MN THIS AFTERNOON AND CONTINUE THROUGH
   THIS EVENING. LIQUID-EQUIVALENT RATES TO 0.10 INCH/HR WILL BE
   POSSIBLE.
   
   DEEP-LAYER LOW PRESSURE OVER THE NRN ROCKIES IS TRANSLATING
   EWD...WITH AN 850-MB BAROCLINIC TROUGH EXTENDING FROM NW TO SE
   ACROSS SD. NORTH OF THE TROUGH AXIS...RUC OBJECTIVE ANALYSIS DEPICTS
   AN 850-MB JET CHARACTERIZED BY E-SELY FLOW OF 50 TO 55 KT.
   CONVERGENCE AT THE NOSE OF THIS JET IS DRIVING WIDESPREAD
   PRECIPITATION ACROSS CNTRL AND SWRN ND. ADDITIONALLY...AN ARCING
   BAND OF CONVECTION...INCLUDING THUNDERSTORMS...CONTINUES TO
   MATERIALIZE FROM S-CNTRL ND INTO N-CNTRL SD. ALL OF THIS
   PRECIPITATION IS FORECAST TO SHIFT EWD ACROSS THE DISCUSSION AREA IN
   TANDEM WITH THE EWD MOTION OF THE AFOREMENTIONED 850-MB FEATURES.
   
   ACROSS S-CNTRL ND...FAR N-CNTRL SD...AND PORTIONS OF W-CNTRL
   MN...FORECAST SOUNDINGS INDICATE THAT SNOW WILL BE THE PREDOMINANT
   PRECIP TYPE WITH GENERALLY SUB-FREEZING TEMPERATURES ALOFT. SNOWFALL
   RATES OF 1 IN/HR WILL BE POSSIBLE...DUE TO APPRECIABLE ISENTROPIC
   ASCENT IN THE 300-310-K LAYER. FARTHER SOUTH...SURFACE TEMPERATURES
   ARE INITIALLY FORECAST TO BE ABOVE FREEZING IN MANY AREAS...YIELDING
   RAIN. HOWEVER...NAM/RUC MODELS SUGGEST THAT SUB-FREEZING LOW-LEVEL
   TEMPERATURES WILL MATERIALIZE AS LOW-LEVEL COLD AIR ADVECTION AND
   EVAPORATIVE COOLING EFFECTS OCCUR. THIS COULD SUPPORT SLEET AND
   FREEZING RAIN...ESPECIALLY AFTER 22Z. FREEZING RAIN RATES OF 0.05 TO
   0.10 INCH PER HOUR WILL BE A CONCERN...ESPECIALLY GIVEN THE
   CONVECTIVE NATURE OF THE PRECIPITATION SUGGESTED BY THE NAM/RUC
   MODELS INDICATING MUCAPE VALUES AOA 200 J/KG. THE PRECIPITATION IS
   EXPECTED TO CONTINUE THROUGH THE EVENING HOURS...WITH THE
   PRECIPITATION TYPE EXPECTED TO BE ALL SNOW BY LATE EVENING.
   
   ..COHEN.. 03/22/2011
   
   
   ATTN...WFO...MPX...FGF...ABR...BIS...
   
   LAT...LON   46139465 45529464 45069551 44889713 44979875 45380008
               46080137 46750047 46749575 46139465