The Chicago National Weather Service Office has issued a Winter Weather Advisory for much of northeast Illinois and the Chicago area north of Interstate-80. Currently rain is falling over a good portion of the region with pockets of sleet or snow. Closer to the Illinois-Wisconsin state line precipitation is turning over to snow. Indications are that while the center of low pressure over southeastern Iowa is moving very slowly east and will be in west-central Illinois early this afternoon, cold air aloft is beginning to shift ahead of the low - causing the air column to cool over southern Wisconsin and northern Illinois - this in turn will accelerate the anticipated changeover back to accumulating snow over the Advisory area. Two to 4 inches - with possibly higher amounts could build up over northeast Illinois by later this evening.
Following is a summary of the Advisory Issued by the National Weather Service and a map below depicting the Advisory area.
Winter Weather Advisory
NATIONAL WEATHER SERVICE CHICAGO IL 1111 AM CST THU FEB 7 2013 THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WINTER WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT FROM 2 PM THIS AFTERNOON TO 9 PM CST THIS EVENING FOR THE FOLLOWING COUNTIES IN NORTHEAST ILLINOIS ..OGLE-DE KALB-KANE-DUPAGE-COOK-WINNEBAGO-BOONE-MCHENRY-LAKE INCLUDING THE CITIES OF...OREGON...DEKALB...AURORA...WHEATON...CHICAGO ...ROCKFORD...BELVIDERE...WOODSTOCK...WAUKEGAN * TIMING...RAIN WILL GRADUALLY CHANGE OVER TO SNOW BY MID-AFTERNOON IN TIME FOR THE EVENING RUSH - SOONER IN THE NORTHERNMOST LOCATIONS CLOSER TO THE ILLINOIS-WISCONSIN STATE LINE.THE SNOW WILL CONTINUE INTO THIS EVENING...BEFORE TAPERING OFF LATER TONIGHT. * ACCUMULATION...SNOW ACCUMULATIONS OF 2 TO 4 INCHES WITH SOME HIGHER AMOUNTS NORTH. THE HIGHEST AMOUNTS WILL BE NORTH OF INTERSTATE 88 AND THE NORTH SIDE OF CHICAGO. * OTHER IMPACTS...THE THREAT FOR A PERIOD OF HEAVY SNOW COULD RESULT IN REDUCED VISIBILITIES UNDER A MILE AT TIMES AND RAPID ACCUMULATION ON AREA ROADS DURING THE EVENING COMMUTE.