National Weather Service update: Excessive heat warning in effect until 7 p.m. Saturday

[July 02, 2012]  At 3:23 p.m. Monday, the National Weather Service in Lincoln issued an excessive heat warning in effect until 7 p.m. Saturday for the counties of Knox, Stark, Peoria, Marshall, Woodford, Fulton, Tazewell, McLean, Schuyler, Mason, Logan, DeWitt, Piatt, Champaign, Vermilion, Cass, Menard, Scott, Morgan, Sangamon, Christian, Macon, Moultrie, Douglas, Coles, Edgar and Shelby, including the cities of Galesburg, Peoria, Bloomington, Normal, Havana, Lincoln, Champaign, Urbana, Danville, Jacksonville, Springfield, Taylorville, Decatur, Charleston, Mattoon and Shelbyville.

Temperatures: High temperatures will be in the upper 90s to around 100 across central and eastern Illinois through the period, with afternoon heat index values of around 105. Widely scattered thunderstorms Monday evening and again Tuesday afternoon in eastern Illinois could reduce the heat near the storms, but the precipitation will increase the humidity levels, keeping heat index values high. The hottest day is expected to be Wednesday, July 4, as temperatures should be over 100 with heat index values around 110.

Effects: The effects of heat are cumulative and worsen as excessive heat continues for several days. Prolonged exposure to the heat may quickly result in heat exhaustion or heatstroke, especially if your body is working hard. With multiple outdoor activities planned for the holiday on Wednesday, extra effort should be made to prepare for the heat. Reduce strenuous activities and drink plenty of fluids.

Precautionary, preparedness actions:

Take extra precautions if you work or spend time outside. When possible, reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heatstroke. Wear lightweight and loose-fitting clothing and drink plenty of water. Never leave children or pets in an enclosed vehicle, as temperatures inside will reach lethal levels quickly.

To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air-conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heatstroke is an emergency; call 911.

Definition: An excessive heat warning means that a prolonged period of dangerously high temperatures will occur. The combination of high temperatures and high humidity will combine to create a dangerous situation in which heat illnesses are likely.

Hazardous weather outlook

In a weather outlook released at 3:09 p.m. Monday, the National Weather Service in Lincoln issued an excessive heat warning in effect until 7 p.m. Saturday for the counties of Cass, Champaign, Christian, Coles, DeWitt, Douglas, Edgar, Fulton, Knox, Logan, Macon, Marshall, Mason, McLean, Menard, Morgan, Moultrie, Peoria, Piatt, Sangamon, Schuyler, Scott, Shelby, Stark, Tazewell, Vermilion and Woodford in central and east-central Illinois.

Monday night: Isolated thunderstorms will be possible Monday evening. Severe weather is not anticipated; however, any storms that develop will be capable of producing gusty winds, small hail and locally heavy rainfall.

Tuesday through Sunday: An extended period of heat and humidity is in store across all of central Illinois through next weekend. Daytime high temperatures will rise well into the 90s each day, with heat index values exceeding 105 degrees.

Graphical depiction updated:
http://www.crh.noaa.gov/ilx/

[Text from National Weather Service, Lincoln office]