Pattern Change Next Week Will Bring Warmer Temperatures to the West While East Stays Cool and Wet

World's First Chief Heat Officer's Tips

A change in the weather pattern will take shape across the United States by next week, heating up the West, keeping the East wet and cool and potentially bringing a break to the recent parade of severe weather outbreaks in the South.

The jet stream will reconfigure itself into a large northward bulge, or ridge of high pressure, over the western U.S., with a broad southward plunge, or trough of low pressure, over the eastern states. For most of April, that ridge of high pressure was situated over the Gulf of Alaska, but it will move into the western Lower 48 by next week.

Temperatures tend to warm up when the jet stream bulges northward, so some parts of the West could have their warmest air so far this year. Meanwhile, a southward dip of the jet stream typically causes a drop in temperatures and more stormy conditions, as will be the case in the East next week.

By Sunday, cooler, drier air should push into the South, bringing a break from the severe weather for a couple of days. However, a threat of thunderstorms will return to parts of the South and Midwest next Tuesday and Wednesday, but the details on the extent of severe weather is uncertain at this time.

Temperatures in parts of the Great Lakes and East will be up to 10 degrees below average early next week, as parts of the West and Plains warm up to 25 degrees above average.

Warmth is already starting to build in the West late this week. The National Weather Service (NWS) office in Los Angeles is expecting "a taste of summer with a heat wave" lasting through the weekend.

On Thursday, downtown Los Angeles soared to 92 degrees, marking the city's first time at 90 degrees or higher since Nov. 18. This is later than the average date of the first 90-degree day of the year in L.A. of April 15. Additional highs in the 90s are expected Friday and Saturday and the NWS has issued heat advisories for parts of coastal Southern California, including Los Angeles.

Additionally, with a high of 91 degrees on Wednesday, Phoenix recorded its first 90-plus-degree day of the year, more than three weeks later than the average of March 31. By Friday or this weekend, the first 100-degree day of the year is likely and the NWS has issued an excessive heat watch for Sunday. The first 100-degree day has occurred within seven days of the first 90-degree day in Phoenix only four other times on record, according to the NWS. As the NWS noted, Tuesday may have been the last day of the season Phoenix fails to hit 90 degrees.

Highs may also surge into the 80s at times early next week along the Front Range of the Rockies and adjacent High Plains, including Denver.

The latest 6- to 10-day temperature outlook from NOAA's Climate Prediction Center highlights the West, especially areas from California to the Southwest, Rockies and adjacent High Plains, as having the highest odds of above-average temperatures into early May.

Parts of the Northeast, Great Lakes and Ohio Valley have the highest odds of below-average temperatures. Not only may it be chilly, but a number of storms systems are expected to drive through the Midwest and Northeast this weekend through the first half of next week, keeping the region wet. Parts of the interior Northeast may even get accumulating snow from each of these systems.

(MORE: Northeast's Unpleasant End to April)

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