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Western US weather

Core of the heat shifts to the Pacific Northwest and the Desert Southwest as coastal California cools down

By Brian Thompson , AccuWeather meteorologist
6/11/2019, 12:26:42 PM

California was the focus of the scorching heat Monday, but the core of the heat will shift to the Pacific Northwest and Desert Southwest into Wednesday. Meanwhile, coastal California will return to a more average weather pattern.

San Francisco International Airport set a June record high of 100 degrees on Monday. That marked the first time that the airport had reached 100 degrees outside of the month of September. Monterey set a new daily record of 97 degrees.

Highs From Monday

Just east of Monterey, in Salinas, the temperature reached 105 degrees, which smashed the old daily record of 87.

The hottest areas near the coast (San Francisco down to Monterey and even Downtown L.A.) will see the temperatures steadily drop over the next couple of days. Tuesday will still be pretty toasty, but the “June gloom” will return later in the week with afternoon highs back in the 60s just in time for the U.S. Open at Pebble Beach.

The worst of the heat is now aimed at Northern California (away from the coast) and the Pacific Northwest as the axis of the ridge shifts into that area.

Western Blog 6/11 NAM Tuesday

The NAM 500-mb forecast late Tuesday, showing the ridge axis extending into the Pacific Northwest.

Tuesday and Wednesday will be scorchers from Redding and Sacramento northward through Medford and Portland. The record highs in Portland (95 on Tuesday, 93 on Wednesday) are both in jeopardy as highs could reach the upper 90s both days.

Wednesday will be the hottest day of the week in Seattle, as temperatures will make a run at 90 degrees. The record high is 85 degrees, which should be pretty easy to reach.

Record highs will likely fall east of the Cascades on Thursday, with record highs possible in Spokane, Yakima and the Tri-Cities.

The Southwest is also going to get in on the heat as well, with temperatures expected to top 110 degrees in Phoenix Tuesday and Wednesday.

The ridge will collapse toward the end of the week and the jet stream will really flatten out later this week into the weekend, which will bring back a more typical June pattern over the Northwest.

Western Blog 6/11 NAM Graphic 2

The NAM valid late Friday, showing a much flatter and progressive flow than earlier in the week. This will lead to much more typical June weather across the West.

Aside from some pop-up thunderstorms in the high terrain from the Cascades and Sierra eastward, rain chances will remain limited over the West through next week.

The one exception may be a trough swinging into the Pacific Northwest late this weekend, although that may mostly skirt to the north. Even if it does come farther south, any rain that does fall over Washington State would be pretty meager.

Wildfire Concern Areas:
Now that we’re heading into wildfire season in the West (and we’ve already seen several small but impactful fires in the past week), I’m going to have a section at the end of nearly every blog post through the end of the fall highlighting any areas of significant concern on posts where fires are not the main topic.

The biggest concern in the short term will be in the Desert Southwest Thursday into Friday. Take Tucson, Arizona, on Thursday; high temperatures will be around or above 105, with dew points in the teens and 20s. Winds will gust over 20 mph at times, so the fire threat will be elevated across much of Arizona.

The gusty breezes will shift a bit to the east on Friday, with the biggest fire threat being across eastern Arizona and western New Mexico.

In the Pacific Northwest, the occasional bout of breezy conditions along with isolated thunderstorms east of the Cascades could elevate the fire threat later this week.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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Western US weather