The National Weather Service Chicago/Romeoville office will begin issuing a new drought product when any part of north central or northeast Illinois, or northwest Indiana are in category D2 or 'severe' drought on the weekly U.S. Drought Monitor. The product will be available under the AWIPS identifier CHIDGTLOT or WMO header AXUS73 KLOT.
The National Weather Service Chicago/Romeoville office will begin issuing a new air quality product when the Illinois Environmental Protection Agency and/or Indiana Department of Environmental Management issue an Air Quality Action Day for the Chicago metro area of northeast Illinois or northwest Indiana. The product will be available under the AWIPS identifier CHIAQALOT or WMO header AEUS73 KLOT.
The National Weather Service offices serving Illinois and Indiana will use new heat watch, warning, and advisory criteria this summer, except in Cook County/Chicago where special criteria was established after the deadly heat wave of 1995. The purpose of the change was to standardize the criteria across much of the western Great Lakes and Ohio Valley and to recognize studies that show that long duration heat events (2 days or more) are potentially deadlier. The new criteria for areas outside of Cook County are;
Excessive Heat Watch/Warning - Maximum Heat Index of 105 or greater and minimum Heat Index of 75 or greater for a time period 48 hours or greater. A watch is typically issued a day or 2 before the heat event, when there is still some uncertainty on the timing or intensity of the heat. A warning is typically issued 6 to 18 hours before the heat event when confidence is high that a life threatening heat event will occur.
Heat Advisory - Maximum Heat Index of 100 or greater or maximum temperature of 95 or greater.
The Excessive Heat Watch/Warning criteria for Cook County/Chicago will remain - maximum Heat Index of 100-105 for three days or more, or maximum Heat Index of 105-110 for two days or more, or maximum Heat Index of 110 or greater for at least one day. Meteorologists also consider the amount of sunshine and minimum overnight temperatures for the lower end events. Heat Advisories are not issued for Chicago.
Excessive Heat Watches, Excessive Heat Warnings and Heat Advisories will continue to be issued under the AWIPS identifier CHINPWLOT or WMO header WWUS73 KLOT.