Last week, the core of excessive heat migrated north and west into thePacific Northwest, where it shattered temperature records in the states ofWashington and Oregon. At the same time, heat moderated over the Plains as theshots of cool air flowed out of Canada.This week, the weather map will be dramatically reshuffled .

Low pressure hovering off shore as of Monday will be key to upcoming trends.

At midweek, this low together with an accompanying cool pool will move to theeast. It will shift inland on Thursday then track over the Inter Mountainregion to the northern Plains by Saturday.

Western cooling will reach far inland on Thursday and Friday with nearly allof the West becoming cooler than usual. No more Northwestern heat. Moreover,outbreaks of showers and thunderstorms over the interior Northwest and eastinto the northern High Plains will unleash local heavy rain and high winds.

Farther east, hot air pooled over the southern half of the Plains at thefirst of the week will begin to spread northeastward on Thursday and Friday.

Temperatures will soar late in the week over the Mississippi Valley to theGreat Lakes and Ohio Valley. The East will feel this change in time for theweekend.

Story By AccuWeather.com Senior Meteorologist Jim Andrews