LOCATION.-- Latitude 41°57'55", longitude 87°52'53" (NAD of 1927), in NE1/4NW1/4NW1/4 sec.16, T.40 N., R.12 E., Cook County, Hydrologic Unit 07120004, on Montrose Road 500 ft West of Mannheim Road, and located on the fence 100 ft past a guard house of the O'Hare Airport at Chicago.

PERIOD OF RECORD.--

PRECIPITATION: October 1, 1998 to current year.

GAGE.-- An 8-in.-diameter, unheated, tipping-bucket rain gage.

REMARKS.-- Snowfall-affected data can result during cold weather when snow fills the rain-gage funnel and then melts as temperatures rise. Snowfall-affected data are subject to appreciable errors.

EXTREMES FOR PERIOD OF RECORD.--

PRECIPITATION: Maximum daily total, 3.59 in., August 22, 2002.