Moderate

* WHAT...High temperatures in the 90s below 5500 feet expected. * WHERE...Riverside County Mountains and San Diego County Mountains. * WHEN...Until 8 PM PDT this evening. * IMPACTS...Hot temperatures 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.

* WHAT...High temperatures up to 102 and morning lows up to 75 expected. Widespread Moderate HeatRisk will be present with areas of Major HeatRisk in the foothills where the thermal belt is strongest and in urban areas. * WHERE...The San Joaquin Valley, Sierra Nevada Foothills, and West Side Hills along the Coastal Range. * WHEN...Until 10 PM PDT this evening. * IMPACTS...Hot temperatures may cause heat illnesses, especially those without effective cooling and/or adequate hydration.

Areas of fog developed this morning, with visibilities generally around 1-3 miles. There are patches of dense fog with visibilities less than 1/2 mile or less at times. Motorists should be prepared for rapid changes in visibilities across short distances, and allow for some extra following distance between vehicles. Visibilities are expected to improve shortly after sunrise.

* WHAT...Visibility one quarter mile or less in dense fog. * WHERE...Boone, De Kalb, La Salle, Lee, Ogle, Winnebago, DuPage, Kane, Kendall, and McHenry Counties. * WHEN...Until 8 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...Visibility one quarter mile or less in dense fog. * WHERE...Northern Will County. * WHEN...Until 8 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.

The combination of hot temperatures and elevated humidity levels will produce heat index values between 108 and 111 degrees for several hours this afternoon into this evening. A few locations may briefly experience heat index values above 111 degrees. If you plan to spend time outside, drink plenty of water, wear light weight and light colored clothing and take frequent breaks from the heat. Young children and pets should never be left unattended in vehicles.

* WHAT...Heat index values up to 107 degrees are expected. * WHERE...Portions of East Arkansas, North Mississippi, and West Tennessee. * WHEN...From 11 AM this morning to 8 PM CDT 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.

Fog will occasional reduce visibilities to less than a half mile. Visibilities will improve between 8 AM and 9 AM. Until then, drivers should be prepared for fluctuating visibilities in fog. Slow down and allow plenty of room between you and the vehicle in front of you.

At 401 AM CDT, Doppler radar was tracking strong thunderstorms along a line extending from 10 miles southwest of Plymell to near Ulysses to 7 miles north of The Saunders Elevator. Movement was southeast at 20 mph. HAZARD...Wind gusts of 50 to 55 mph. SOURCE...Radar indicated. IMPACT...Gusty winds could knock down tree limbs and blow around unsecured objects. Strong thunderstorms will be near... Ulysses, Johnson City, Manter, Big Bow, and Hickok around 405 AM CDT. Ryus around 415 AM CDT.

* WHAT...Visibility of one-quarter mile or less in dense fog. * WHERE...Bureau, Putnam, Carroll, and Whiteside Counties. * WHEN...Until 8 AM CDT this morning. * IMPACTS...Low visibility could make driving conditions hazardous. If driving, slow down, use your low-beam headlights, and leave plenty of following distance ahead of you.