Western heat wave to continue through 3rd week of July

While the severity of the heat wave will wane some as the core of a heat dome shifts, dangerous triple-digit temperatures will continue to be common across the West well into the second half of July.

Key Takeaways:

• The heat wave that has been sizzling the West during the first part of July has expanded eastward but will also continue to bake much of the region during the third week of the month.

• Salt Lake City will be near the core of the heat, as temperatures will resurge into triple-digit territory and near records by the middle of the week.

• The practical effects of a long-term heat wave include an elevated risk of fires, expanding drought conditions and increased energy demand.

A blistering heat wave that has been roasting the West since the beginning of July relented in some areas this past weekend but will also continue to expand its footprint to the east across the central United States, challenging records over the next several days, warn AccuWeather meteorologists.

Temperatures in Wichita, Kansas, will come close to levels not seen on July 15 since the Dust Bowl Era of the 1930s. Widespread highs in the upper 90s to 100s will be experienced over the central and southern Plains Monday afternoon and evening. A front will help to cool portions of the Plains down a bit by midweek. However, areas west of the Continental Divide will continue to bake away and, in some cases, throttle up once again.

Salt Lake City is one major metro area over the Great Basin where near-record highs and triple-digit heat are forecast this week.

The expansion of this heat dome is part and parcel of a very hot weather pattern across a large portion of the country, with heat-related advisories also in effect in parts of the South and East.

While the heat will ease across areas farther west, where all-time record highs were set over the last couple of weeks, it will not cease. Temperatures will remain above the historical average into the second half of July, raising the risk for fires and expanding drought conditions.

The core of the heat has shifted east... for now

For the better part of the beginning of July, residents of the central U.S. have enjoyed temperatures near or below average, in stark contrast to their neighbors to the west. Recently, they could no longer claim such comfort.

"After an extended, record-breaking heat wave across California, Oregon, Washington and Nevada, the heat dome responsible for those records has begun to shift east," said AccuWeather Meteorologist Brandon Buckingham.

As a result of the heat, heat advisories and excessive heat warnings are plastered across the central Plains at the start of this week.

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AccuWeather RealFeel® Temperatures, which combines a number of factors such as the temperature, humidity, amount of sunshine and wind to give a more realistic representation of how it feels, will be several degrees above the actual thermometer readings for most, especially in the Midwest, where humidity levels will be elevated.

On the edge of the heat dome, rounds of showers and thunderstorms will cut the heat across the Northeast and Ohio Valley, from New York to Missouri bringing a risk for torrential rain and damaging winds.

More sustained relief will arrive later in the new week for the Central states as a cold front sweeps in a cooler and drier air mass from Canada beginning in the middle of the week.

Western heat has waned in intensity, but it will persist

For heat-weary residents of the interior West, it has been a sultry first half of July, with numerous records falling to the wayside thanks to the massive heat dome. Since it has contracted to the east, a slight break in the heat has arrived, especially across the Northwest, and this will expand south into California, say AccuWeather meteorologists.

"Although it will still be hot in places like Sacramento and Fresno, California, we do not expect additional records to be broken through the middle of the new week," said Buckingham.

Instead, temperatures will be about 5-10 degrees above the historical average in places like Las Vegas and Phoenix, which are still well into the 90s and even into triple-digit territory.

Las Vegas had a blistering stretch of record high temperatures from July 6 to 12, tying or setting record highs each day, including an all-time record high of 120 on July 7. On Sunday, the high was 106, which ended a stretch of highs in the 110s to 120 that dated back to July 3.

While relief will be felt closer to the coast and in the Northwest, and also in the Midwest, the Intermountain West and northern Rockies region will bear the worst of the heat for the new week, thanks to a bulge in the jet stream that will keep temperatures in triple-digit territory for some deep into the second half of July.

As of Monday, the AccuWeather forecast for Boise, Idaho, calls for high temperatures to be near or above 100 degrees through Monday, July 29, with only modest relief thereafter. The historical average high temperature in Boise is in the low to mid-90s for the rest of the month.

Subtle shifts in the heat dome will also open the door to some monsoon moisture and thunderstorm activity in the Southwest.

"As the heat dome moves, the corridor of monsoon thunderstorm activity will also shift," said Buckingham. "The moisture will not be overly impressive, but there will be an elevated risk of thunderstorms and spotty fires across the Four Corners region for the new week."

Outside of the area in the Southwest where thunderstorms are possible, it will be bone-dry. The combination of the lack of rainfall and high temperatures will expand the drought footprint, especially across the Rockies.

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