SPC MD 44



MD 0044 CONCERNING FREEZING RAIN FOR EASTERN IOWA…NORTHERN ILLINOIS AND FAR SOUTHEAST WISCONSIN.

MD 0044 Image


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 

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