Mesoscale Discussion 1884
   NWS Storm Prediction Center Norman OK
   1002 AM CST Tue Dec 29 2020

   Areas affected...Northeast KS...Eastern NE...Southwest/central
   IA...Northern MO

   Concerning...Winter mixed precipitation 

   Valid 291602Z - 292100Z

   SUMMARY...Moderate to occasionally heavy winter precipitation will
   continue into this afternoon. The snow/freezing rain and freezing
   rain/rain lines should gradually shift northward with time, with
   some sleet possible within the snow/freezing rain transition zone.

   DISCUSSION...At 16Z, a broad plume of winter precipitation is
   ongoing from central KS into portions of IA/NE and northern MO, with
   embedded convective elements noted across KS and moving into
   southeast NE/southwest IA/northwest MO. This precipitation will be
   sustained into this afternoon, as strong low-level warm advection
   maintains ascent in advance of a complex mid/upper-level trough
   moving into the central/northern Plains. The warm advection will
   also result in a northward transition of the snow/freezing rain and
   freezing rain/rain lines with time. Some sleet will be possible
   within the snow/freezing rain transition zone, though surface
   observations and forecast soundings indicate that freezing rain and
   snow will remain the predominant precip types for at least the
   remainder of the morning. 

   While widespread and occasionally moderate/heavy, precipitation has
   thus far been somewhat disorganized, with heavier rates being
   relatively transient at any given location. However, heavier
   precipitation over KS is expected to spread northeastward at a
   faster rate than the precip type transition zones, resulting in more
   widespread snow rates of 1+ inch per hour across far eastern NE into
   western/central IA by early afternoon, and freezing rain rates of
   0.05+ inches/hour from southeast NE/far northeast KS into northern
   MO. Increasing frontogenesis within the 900-700 mb layer will
   support the potential for more organized banding and even greater
   snowfall rates by mid afternoon, primarily across portions of
   southern/central IA.

   ..Dean.. 12/29/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...LSX...DVN...DMX...EAX...OAX...TOP...GID...

   LAT...LON   41009151 40089230 39149383 38629549 39019681 39389772
               40649732 41559684 42059483 42249371 42239259 41909176
               41009151