Storm Prediction Center Mesoscale Discussion 2239

   Mesoscale Discussion 2239
   NWS Storm Prediction Center Norman OK
   0926 AM CST Thu Nov 21 2024

   Areas affected...Northeast IL into extreme northwest IN

   Concerning...Heavy snow 

   Valid 211526Z - 211830Z

   SUMMARY...Snow rates of around 1 inch per hour are possible through
   the morning, along with increasingly gusty winds and reductions in
   visibility.

   DISCUSSION...Moderate to locally heavy snow is ongoing this morning
   across southeast WI and far northeast IL, immediately in advance of
   a midlevel vorticity maximum and compact surface low moving
   south-southwestward over Lake Michigan. This area of snow will
   continue to move southward across parts of northeast IL and adjacent
   parts of northwest IN through the remainder of the morning, in
   conjunction with stronger ascent attendant to the midlevel vorticity
   maximum. 

   With initially cold temperatures through a relatively deep column
   (with 700 mb temps of -10 to -15 C), sufficient ascent through the
   dendritic growth zone will continue to support heavier snow rates,
   and 1 inch per hour rates are possible at times through late morning
   into the early afternoon. In addition, as stronger low-level flow
   along the western periphery of the compact cyclone over Lake
   Michigan moves southward, wind gusts in excess of 30 mph will
   further support reductions in visibility.

   ..Dean.. 11/21/2024

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

   ATTN...WFO...LOT...

   LAT...LON   42478835 42488784 42298770 41678732 41278724 41038759
               41178802 41518841 41958862 42298866 42418857 42478835