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Mesoscale Discussion 1658
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   Mesoscale Discussion 1658
   NWS Storm Prediction Center Norman OK
   0354 AM CST Sun Nov 25 2018

   Areas affected...Central...north-central and northeast
   KS...southeast NE...southwest IA...and northwest MO

   Concerning...Heavy snow 

   Valid 250954Z - 251600Z

   SUMMARY...Snowfall rates up to 1-2 inches per hour will increase
   from west to east during the late overnight through this morning. 
   In addition to heavy snow, strengthening northerly winds through the
   morning will produce a blizzard with reduced visibilities in
   whiteout conditions.

   DISCUSSION...Short-term guidance remains consistent with the
   forecast for a vigorous shortwave trough, now located over eastern
   CO, to emerge eastward across KS overnight, with deepening of this
   system between 12-18Z as it reaches eastern KS/western MO by late
   morning.  Trends in mosaic radar imagery showed a band of
   precipitation had developed from north-central KS to southeast NE. 
   This corridor in the northern part of the discussion area is
   expected to be the first southwest-northeast oriented zone to change
   to snow and increase in rates as surface temperatures fall through
   the lower 30s to upper 20s F by 11-12Z.  This same trend with snow
   developing across the rest of the discussion area after daybreak
   from central to northeast KS and far northwest MO to southwest IA
   will occur as the surface low shifts east-northeast into MO.  This
   will allow low-level winds on its north-northwest periphery to back
   to northerly and strengthen, ushering in colder temperatures, and
   supporting a high likelihood for reduced visibilities in whiteout

   Meanwhile, an increase in upward vertical motion through the
   dendritic-growth zone per forecast soundings is expected as, 1) the
   shortwave trough deepens with eastward progression and 2) within the
   exit region of a strengthening 500-mb 100-kt jet spreading across
   northeast KS/northwest MO this morning.  This factor which is
   expected to become stronger by 15-18Z suggests snowfall rates could
   be up to 2 inches per hour, generally north of a line from KSLN to
   KSTJ to 25 S KLWD, while the initial aforementioned band of snow
   could have rates up to 1 inch per hour.  Forecast soundings also
   indicated weak elevated instability rooted around 600 mb, given the
   likelihood of steepening midlevel lapse rates (around 8 C/km) in the
   exit region of the midlevel jet.  This could enhance snowfall rates.

   ..Peters.. 11/25/2018

   ...Please see for graphic product...


   LAT...LON   41259537 41359315 41159252 40309380 39249539 38409689
               38239774 38379854 38699916 38909976 39289995 39479979
               40099877 40489775 40979632 41259537 

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