<pre>ACUS11 KWNS 222037 SWOMCD
Mesoscale Discussion 0044 NWS Storm Prediction Center Norman OK 0236 PM CST Tue Jan 22 2019
Areas affected…Eastern Iowa…Northern Illinois and far southeast Wisconsin.
Concerning…Freezing rain
Valid 222036Z – 230030Z
SUMMARY…Light to moderate freezing rain is overspreading much of Eastern Iowa, northern Illinois and far southern Wisconsin.
DISCUSSION…Freezing drizzle has been falling for most of the day across the MD area with ice accretion rates around 0.01 to 0.03 inches per hour. Ice accumulation has shown to be efficient so far with ice accretion at least twice the water equivalent at most observing sites. This efficient icing is likely due to a combination of light precipitation rates, well below freezing surface temperatures, and winds around 10 to 15 mph. These rates will be increasing over the next few hours as heavier precipitation spreads from west to east. The first signs of these increasing rates can be seen on radar in southeast Iowa and western Illinois as well as central Illinois.
Precipitation is currently falling as freezing drizzle/freezing rain across the entire MD area as the DGZ is yet to saturate across northern Illinois and southern Wisconsin despite the entire column being cold enough to support snow. Therefore, expect precipitation to change to snow in these areas as the column saturates and precipitation rates increase within the next few hours. The HREF shows very little movement of the warm air aloft through the evening, so the rain/snow line is expected to stay within a county either side of the 0C 850mb line on the graphic.
The timing of this heavier freezing precipitation will coincide with the evening commute across the highlighted area including the Quad Cities, Chicago, Rockford, and Milwaukee. In addition, road conditions are expected to worsen after dark as the warming effects of filtered sunlight go away and precipitation rates increase.
Through time, surface temperatures are expected to increase south of the rain/snow line which will eventually end the freezing rain for most areas and result in snow north and rain south by late this evening.
..Bentley.. 01/22/2019
…Please see www.spc.noaa.gov for graphic product…
ATTN…WFO…LOT…ILX…MKX…DVN…
LAT…LON 40389127 40549160 40709194 41169186 41449160 41779107
42419019 42638968 42808873 42738814 42698779 42518779 42398777 42238775 42138764 41968756 41848749 41728742 41598740 41428747 41288796 41148850 41038909 40838939 40678968 40559002 40479043 40379084 40389127 </pre>
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