World's First Chief Heat Officer's Tips

Colder temperatures and even high-mountain snow have pushed into the West for the official start of summer from a weather pattern change that is also heating up the South.

A sharp by late June standards southward plunge of the jet stream carved out over the West and will inch its way into the Plains over the weekend.

The most noticeable impacts from this change was in the West, where temperatures plunged 10 to 20 degrees below average across interior parts of the region through. Cooler-than-average temperatures also expanded into the High Plains.

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Missoula, Montana, tied its record-cold high of 56 degrees on Thursday.

It was cold enough for snow in parts of the northern Rockies above 6,000 feet in elevation, including at Glacier National Park. Snow is not unheard of in the northern Rockies this time of year. In fact, snow fell in this region just days before the Fourth of July last year.

Snow also fell above 9,000 feet at Rabbit Ears Pass, southeast of Steamboat Springs, Friday morning.

Those with outdoor activities planned in the lower elevations of the northern and central Rockies where it's not snowing should be prepared for wet and cool conditions into the weekend.

On the opposite side of the spectrum, Oklahoma City recorded its first 90-degree temperature of the year Thursday afternoon, and Kansas City could see its first 90-degree high Friday or Saturday. Oklahoma City typically sees its first 90 in early May, so this was more than a month behind schedule. It was also the muggiest day in Oklahoma's capital city in almost nine years.

It's possible that the general theme of this weather pattern will persist through the final week in June.

Forecast guidance is indicating that another southward plunge of the jet stream could move into the West Coast next week. That may allow temperatures to remain below average in parts of the West. At the same time, portions of the central and eastern states could be favored to see above-average temperatures.

The latest 6- to 10-day temperature outlook from NOAA's Climate Prediction Center generally shows this theme by favoring above-average temperatures next week in parts of the central and eastern states. Most of the West has increased odds of below-average temperatures. There remains some uncertainty with exactly how the large-scale weather pattern will set up, so changes to this forecast are possible.