From Tom Skilling at 4:58 p.m.
Official highs Thursday: 90 O'Hare, 92 Midway. Hottest feeling day of the year when humidity is factored in. Heat indices: 100 Midway and 99 O'Hare. This makes it the ninth day of 2010 with a 90-degree or hotter temperature -- more than twice the four days of 90s which occurred all of last year!!!
From Tom Skilling at 10:37 a.m.
Severe weather threatens today -- especially in southern sections of the Chicago area.
The most humid air mass in nearly 11 years -- by some accounts just west of Chicago -- fueled powerhouse thunderstorms which produced nearly 200 reports of severe weather filed Wednesday and Wednesday night with the Storm Prediction Center. That included 10 reports of twisters.
Wisconsin and Minnesota were hard hit. Local 4-5-inch rains were reported in sections of the Badger State.
Dew points reached the upper 80s in parts of Iowa Wednesday -- extraordinary levels more typical of the Persian Gulf, home to some of the world's highest dew points. Combined with 90-plus temperatures in Iowa, these high moisture levels produced heat indices which topped 120 degrees at some locations!
Heat advisory for Chicago's southern suburbs
From Mike Hamernik at 8:04 a.m. | http://twitter.com/MikeHamernik
A heat advisory is in effect until 7 p.m. today for many of Chicago's southern suburbs as well as most of northern Indiana. This advisory is roughly along and south of Interstate Highway 80 and includes Will, Grundy, Kankakee, Porter, LaPorte and Lake (Indiana) counties.
The heat index is expected to reach 105 degrees this afternoon over the advisory area.
The human body can lose its natural cooling mechanism when the heat index reaches this benchmark, leading to an increased risk of heat exhaustion or heat stroke.
Individuals working outdoors or engaged in strenuous activities are particularly at risk.
Common sense can prevent most heat related problems. Limit outdoor activity, stay out of the sun, and help your body keep up with stifiling humidity by cooling down in an air-conditioned environment. Staying hydrated will also help your body deal with the heat.
A heat advisory is issued by the National Weather Service when a heat index of 105 to 115 degrees is expected for at least a three-hour period.
Excessively warm nighttime temperatures that do not fall below 80 degrees for two or more nights may also trigger a Heat Advisory.
Chicago area counties under a heat advisory today:
This has nothing to do with global warming or climate change. These aren't the droids you're looking for.