Ice Storm Warnings Now In Effect! Potential Major Event To Start This Evening

Ice storm warnings are now in effect as model guidance continues to support increasing confidence in the potential for a significant icing event. These warnings, as shown below, cover much of northern Illinois and adjacent parts of Iowa 

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INCLUDING THE CITIES OF WOODSTOCK, WAUKEGAN, DEKALB, AURORA, 
ELGIN, WHEATON, CHICAGO, OTTAWA, OSWEGO, MORRIS, AND JOLIET
331 AM CST TUE FEB 5 2019

...ICE STORM WARNING IN EFFECT FROM 6 PM THIS EVENING TO 6 AM CST
WEDNESDAY...

* WHAT...SIGNIFICANT ICING EXPECTED DUE TO FREEZING RAIN. ICE
ACCUMULATIONS OF ONE TENTH TO FOUR TENTHS OF AN INCH EXPECTED...
WITH THE HIGHEST ICE AMOUNTS ALONG AND NORTHWEST OF A LINE FROM
STREATOR TO MORRIS TO JOLIET TO DOWNTOWN CHICAGO. SOME SNOW AND
SLEET MAY MIX WITH THE FREEZING RAIN EARLY IN THE EVENING.

* WHERE...PORTIONS OF NORTH CENTRAL AND NORTHEAST ILLINOIS.

* WHEN...FROM 6 PM THIS EVENING TO 6 AM CST WEDNESDAY.
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It is important to note than an icing event of this magnitude is rare in this part of the country. Conditions have to come together just right. Stay tuned for latest forecast updates, it won't take much to turn this into a mix or even sleet event. 

Ice accumulations over .25" (a quarter of an inch) can start to break tree limbs and cause power outages. Even if we DONT see these values, it is also important to remember that even the thinnest glaze of ice will cause significant travel hazards. Black ice can form rapidly!

When will the ice start?

​Current indications are by the Tuesday evening rush we will see freezing rain enter northern illinois from the west. 

As the night progresses, precipitation rates along the leading wave will reach the Chicago metro area. This is when/where the heaviest icing rates may occur, especially across the northwest suburbs. 

As we approach sunrise Wednesday morning, freezing rain should either end or change over to plain rain as warmer air is pulled northward. Ice Storm Warnings may expire at this time, but that doesn't mean there wont still be hazards especially on untreated surfaces. 

Below is our latest TAM. Expect more updates this afternoon and possible revisions to this map as the event begins to start. As I mentioned above, ice storms around here are very rare, and require a set of meteorological ingredients to come together in just the right way. ISC will be here to bring you all the latest. 

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