IF IT AIN'T ONE THING IT'S ANOTHER...
The last two weeks have been warm ones around the Midwest. You can see the core of the warmth focused on the central Midwest and Ohio Valley.
Precipitation was below normal over the central Midwest with the primary storm track cutting through the Plains.
These are the July rainfall totals around the Midwest ending the 15th.
Here are the actual departures for the same period.
The next 24 hours do hold the promise for more storms over the NE half of Iowa, SW Wisconsin, SE Minnesota, and N. Illinois. This is on the northeast edge of the expanding heat dome that will bake the area Thursday through Saturday. This region known as the ring of fire, will have the potential for strong storms and locally heavy rain. The Storm Prediction Center has a slight risk outlook area for severe thunderstorms Wednesday afternoon and evening.
Aside from the severe threat, these storms will be loaded with moisture and have a good chance of putting out some hefty rainfall totals. The NAM has amounts that look like this.
The hi-res 3K NAM has a similar appearance.
By Thursday the atmosphere should turn very warm aloft creating a cap that prohibits thunderstorms. As a result temperature are expected to surge as dew points peak in the mid 70s. The heat index values will reach into the dangerous range of 105 to 110 degrees. As a result excessive heat warnings have been issued for some areas from Wednesday afternoon through Saturday. Further north of the warnings a watch is in effect.
The heat should be at its peak Thursday-Saturday. This is what I'm projecting for highs and heat index values in Cedar Rapids Thursday through Saturday. The numbers should be similar over much of the central Midwest.
For those not enamored with the heat, it is expected to break Sunday as we undergo a pattern change to northwest flow. Here's the 500 mb jet stream Friday when the heat is in full force.
This is it next Wednesday. Notice the change in heights from the hot humid southwest flow to the cooler drier NW flow that originates in Canada.
The cool-down is apparent on the EURO with highs going from about 100 into the lower 80s. Much less humidity too with dew points progged in the upper 50s!