Changes are brewing in the longer range and the latest JMA Weeklies illustrate this nicely.

Week 1

No changes are needed to the expected significant heat wave to open the month of July.  Heat and humidity will reach excessive levels at times- heat indices of 100° to 110° at times.  While isolated coverage of storms are possible a few of the days (primarily afternoon and evening variety), it’s a dry pattern, overall.

Week 2

The pattern is in a transitional period during this time frame as the upper ridge retrogrades west.  While still warm, the hottest conditions will shift west under the upper ridge.  The other take-away?  An active northwest flow returns with an emerging “ring of fire” pattern.

Weeks 3-4

While perhaps a bit quick, the model reverses things entirely by the Weeks 3-4 time frame.  There’s no denying we think the hottest period of the summer will be behind us by mid-July, and while this type pattern shown below is where we think the dominant overall pattern is heading for the second half of summer, the model may be a bit aggressive here.  Regardless, the Weeks 3-4 time frame are expected to not only reverse, but turn cooler than average over the Great Lakes region.