Mesoscale Discussion 1883
   NWS Storm Prediction Center Norman OK
   0400 AM CST Tue Dec 29 2020

   Areas affected...Much of KS and far northwestern OK

   Concerning...Winter mixed precipitation 

   Valid 291000Z - 291600Z

   SUMMARY...Freezing rain should occur this morning before gradually
   turning to rain from south to north. Freezing rain rates may exceed
   0.05 inch per 3 hours. Some snow/sleet may also mix with the
   freezing rain, mainly across parts of northern Kansas.

   DISCUSSION...A 40-50+ kt southerly low-level jet will continue to
   transport moisture northward across the southern/central Plains this
   morning. Strong forcing for ascent associated with this low-level
   jet has encouraged the development of scattered to numerous showers
   across northern OK and much of central/eastern KS. An initially dry
   sub-cloud layer across these areas is gradually becoming saturated
   as precipitation continues. Evaporative cooling to the surface wet
   bulb temperature should result in a period of freezing rain for at
   least a few hours this morning across far northwestern OK and much
   of KS, where surface air temperatures are or will soon fall below
   freezing. The light to moderate and showery precipitation should
   support freezing rain rates around 0.05 inch per 3 hours, with
   locally higher rates possible with convection that may produce
   isolated lightning flashes with very weak elevated instability.
   Still, ice accretion may remain limited to elevated surfaces for
   most locations due to the marginal surface temperatures. The best
   potential for ice accretion appears to be across parts of
   north-central into northeastern KS, where surface temperatures
   should generally remain below freezing this morning.

   Continued robust low-level warm advection is expected to gradually
   erode the near-surface sub-freezing layer from south to north across
   this region through the morning, as surface winds veer from easterly
   to southeasterly. Accordingly, a transition from freezing rain to
   rain should occur across far northwestern OK and parts of
   southern/central KS by 16Z (10 AM CST). A mix of freezing rain,
   sleet, and/or snow also appears possible across mainly northern KS,
   where the low-level warm nose will not be as pronounced compared to
   locations farther south.

   ..Gleason.. 12/29/2020

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

   ATTN...WFO...EAX...TOP...ICT...OUN...GID...DDC...GLD...AMA...

   LAT...LON   37899794 37419871 36699916 36439964 36670051 37430083
               38250072 39129999 39889814 39959681 39879573 39489508
               38759494 38309587 38109708 37899794