Moderate

* WHAT...Visibility of one quarter mile or less in dense fog. The fog is expected to impact the morning commute. Visibilities may change suddenly over very short distances. * WHERE...Benton, Jones, Linn, Buchanan, Delaware, and Dubuque Counties. * WHEN...Until 10 AM CDT this morning. * IMPACTS...Low visibility could make driving conditions hazardous. If driving, slow down, use your headlights, and leave plenty of distance ahead of you.

* WHAT...Heat index values up to 104. * WHERE...Portions of northwest and west central Illinois, east central and southeast Iowa, and northeast Missouri. * WHEN...Until 7 PM CDT Thursday. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in

* WHAT...Visibility 1/4 mile or less in dense fog. * WHERE...Portions of central Upper and western Upper Michigan. * WHEN...Until 9 AM EDT /8 AM CDT/ this morning. * IMPACTS...Low visibility could make driving conditions hazardous. * ADDITIONAL DETAILS...Areas in the lower elevations, particularly along the Lake Superior shoreline, may not experience dense fog. Be prepared for changing conditions as you head inland. If driving, slow down, use your headlights, and leave plenty of distance ahead of you.

A large and disorganized tropical disturbance is located east- northeast of the Marianas and is producing isolated to numerous, locally heavy showers and isolated thunderstorms. This system is expected to move through or just north of the Marianas over the next two days. A col has developed over the Marianas between this disturbance and another system to the northwest. This will keep winds fairly light through Wednesday. The unstable airmass and high

* WHAT...Heat index values of 100 to 110 expected. * WHERE...Portions of central, east central, north central, and northeast Illinois and northwest Indiana. * WHEN...For the first Heat Advisory, from noon CDT /1 PM EDT/ today to 9 PM CDT /10 PM EDT/ this evening. For the second Heat Advisory, from noon CDT /1 PM EDT/ to 9 PM CDT /10 PM EDT/ Wednesday. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. Drink plenty of fluids, stay in an air-conditioned room, stay out of

* WHAT...Heat index values of 100 to 110 expected. * WHERE...Boone, De Kalb, Lee, Ogle, Winnebago, Central Cook, DuPage, Kane, Lake IL, McHenry, and Northern Cook Counties. * WHEN...From noon today to 9 PM CDT this evening. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS...If showers and thunderstorms move across the area later this morning, the hot temperatures may not materialize. Drink plenty of fluids, stay in an air-conditioned room, stay out of

* WHAT...Heat index values of 100 to 110 expected. * WHERE...Portions of central, east central, north central, and northeast Illinois and northwest Indiana. * WHEN...For the first Heat Advisory, from noon CDT /1 PM EDT/ today to 9 PM CDT /10 PM EDT/ this evening. For the second Heat Advisory, from noon CDT /1 PM EDT/ to 9 PM CDT /10 PM EDT/ Wednesday. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. Drink plenty of fluids, stay in an air-conditioned room, stay out of

* WHAT...Heat index values up to 100 degrees expected. * WHERE...In Delaware, New Castle County. In New Jersey, Mercer, Camden, Gloucester, and Northwestern Burlington Counties. In Pennsylvania, Delaware, Eastern Chester, Eastern Montgomery, Lower Bucks, and Philadelphia Counties. * WHEN...From noon today to 8 PM EDT this evening. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.

Areas of locally dense fog will affect northwest Wisconsin through early this morning, with visibilities to 1/4 mile or lower. Visibilities are expected to improve within a few hours after sunrise this morning. If traveling early this morning, reduce your speed and use low-beam headlights when encountering foggy areas. A Dense Fog Advisory may be needed. Keep updated on the latest forecast for fog development trends.

* WHAT...Heat index values up to 101 expected. * WHERE...Bureau and Putnam Counties. * WHEN...From 1 PM this afternoon to 7 PM CDT Thursday. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in