Clouds keep temperatures from falling overnight
Temperatures fell into the teens Chicago area-wide this morning with only a few locations recording the forecast single digits. Chicago’s official observation site at O’Hare International Airport hit a low of 17 followed closely by Midway Airport of 18. Yet Rochelle dropped to 1 degree above zero while nearby DeKalb had 12, Freeport dropped to 5 while nearby Rockford reported a 13 degree low, and Waukegan recorded a 9 degree low while Palwaukee/Wheeling airport recorded a low of 13.
All the ingredients were in place for a very cold morning at all Chicago area locations – we had a fresh deep snow cover, diminishing winds and a very cold high pressure centered overhead. The fly in the ointment was cloud cover. Minimum temperatures this morning over the Chicago area were expected to drop into the single digits away from the city. While it was cloudy Tuesday evening, all indications were that the clouds would thin and move off to the east allowing the final ingredient to bring about maximum radiational heat loss and a temperature drop from the 20s into single digits overnight. However, the cloud cover persisted with only breaks in a few places that allowed the temperatures to drop into the single digits.
Following is a list of Chicago area airport locations and their low temperatures – you can tell the many areas that remained cloudy while others experienced an early morning cloud-free period.
Location/ Low temperature