High heat and humidity as well as chances for thunderstorms are set to dominate the forecast this week, and the 4th of July will kick things off with both.
First, thunderstorms will be possible across Central and Northern Iowa through the morning hours. Storms could be strong during the overnight in South Dakota and Nebraska, but should weaken by the time they are crossing Central Iowa, between 7 and 10 a.m.
Once the scattered showers and storms are out of the way, the extra humidity from any rain that may fall plus another warm south wind, will push heat index values over 100 into the 105 degree range by the afternoon. A Heat Advisory will kick in at 1 p.m. for the southwest half of the state including Polk County.
The heat and humidity could spark a second round of evening storms, mainly confined to the northeast third of the state. Some of these storms could be strong to severe, but Central and especially Western Iowa are likely to be capped from warm air aloft, leaving skies generally clear for fireworks displays.
The Heat Advisory will remain in place for an even hotter Tuesday, which will likely end up necessitating an expansion of the advisory further into Central Iowa. With the high heat and humidity in place for most of the week, evening/overnight storm chances will be present just about every night, especially over the northern half of the state.