Mesoscale Discussion 0153
   NWS Storm Prediction Center Norman OK
   0807 PM CST Fri Feb 18 2022

   Areas affected...portions of northeastern Iowa southern Wisconsin
   and northern Illinois

   Concerning...Snow Squall 

   Valid 190207Z - 190500Z

   SUMMARY...Snow squalls should continue this evening approaching
   Chicagoland. Low visibility from blowing and heavy snow may impact
   travel.

   DISCUSSION...Snow has expanded in coverage and intensity along a
   fast-moving arctic front moving across far eastern IA, southern WI
   and northwest IL. Snow squall conditions have been reported at
   numerous observing sites over the last 30 minutes as the band has
   expanded. Driven partly by the strong frontal circulation and steep
   low-level lapse rates advecting ahead of the front from southern NE,
   the shallow convection may persist for several more hours despite
   cooling surface temperatures and a stabilizing boundary layer
   downstream. Current projections place the line into the Chicagoland
   area between 0300 and 0430z.

   If the line is able to continue, strong wind fields associated with
   a strengthening surface cyclone over the Great Lakes will be
   exacerbated by strong vertical momentum transport from the shallow
   convection. Isolated gusts to 50 kts will be possible along with
   moderate to heavy snowfall as the line moves southeast. The latest
   HRRR suggests the line will begin to weaken as it outruns the plume
   of steeper lapse rates from NE and IA. While uncertainty remains,
   some risk for travel impacts appears possible through northern IL
   for a few more hours.

   ..Lyons/Guyer.. 02/19/2022

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

   ATTN...WFO...LOT...MKX...DVN...

   LAT...LON   42248770 41968756 41768750 41598765 41518807 41498830
               41338923 41429022 41629088 41959097 42069073 42618951
               42858894 43058827 43088786 43038781 42718777 42328771
               42248770