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Pacific Northwest to feel a summer preview as high temps outpace Desert Southwest

By Alex Sosnowski, AccuWeather senior meteorologist
May 11, 2019, 4:39:41 PM EDT

A convoluted weather pattern will allow warmth and sunshine to build over the northwestern United States, while much of the Southwest remains cool and unsettled with showers through this weekend.

This time of the year, sunshine can be a big player in warm versus cool weather. However, the jet stream also plays a big role.

The jet stream will maintain a snakelike appearance with a northeastward bulge across western Canada and a southwestward lunge over Southern California, Arizona and northwestern Mexico through Saturday.

The topsy-turvy pattern may hold through the end of the weekend, as well.

Southwest to feel like the Northwest and vice versa

As a result of cloud cover and shower activity in the Southwest and sunshine across the Northwest, parts of the Northwest are forecast to be warmer than some of the deserts at the same time.

Through this weekend, highs in some of the cities in the Southwest, such as Phoenix and downtown Los Angeles, may be significantly lower than that of Seattle, Washington, and Portland, Oregon.

Record-high temperatures were already set across portions of the Pacific Northwest on Thursday. Astoria, Newport, Salem and Eugene, Oregon, are just a few of the locations which tied or broke their previous record high on Thursday, reaching 85, 86, 86 and 87 degrees Fahrenheit, respectively.

Seattle also set a record high on Thursday, reaching 83 F. This broke the old record of 81 F set in both 1987 and 1976. The high of 86 F on Friday also set a new record high.

Even though temperatures will not be flipped as much from north to south on Saturday in comparison to Friday, many areas in the Northwest will still be warmer than some of the deserts.

West Flip Sat

Highs in parts of the Northwest will be 15 to 25 degrees above average, while highs in portions of the Southwest will be 5 to 15 degrees below average.

For example, the average high for Seattle during the middle of May is in the middle 60s, while the average high in Phoenix is in the middle 90s.

The pattern will provide natural air conditioning in the South, while people who do not have air conditioning farther north will wish they had it.

The pattern is likely to be a taste of what is to come this summer.

AccuWeather long-range meteorologists are anticipating hot, dry weather to be the theme across the Northwest and somewhat cooler and wetter conditions in the Southwest this summer.

The pattern may spur on an early fire season in the Northwest.

Warmth to feel like midsummer in the Northwest

The setup across the North allows warmth to build aloft, which limits cloud cover. Strong May sunshine is then able to warm the lower levels of the atmosphere in southwestern Canada and the northwestern U.S.

Adding to the warmth will be a light flow of air that descends from the mountains across the interior to lower elevations near the coast.

"Areas west of the Cascades and Coast Ranges will challenge or break record-high temperatures into this weekend," according to AccuWeather Meteorologist and western U.S. blogger Brian Thompson.

Pac NW warmth 5-10-19

In some cases, daily high temperature records that were set in the 1950s, 60s and 70s will be challenged in the Northwest.

"Temperatures in the Northwest will surge to levels more typical of midsummer with highs generally in the 80s and in some cases the lower 90s," according to AccuWeather Meteorologist Renee Duff.

AccuWeather RealFeel® Temperatures will be 5-10 degrees higher than the actual temperature during the late-morning and afternoon hours.

People who must work in the heat and are not used to such conditions should take frequent breaks. All those exercising or working in these conditions should drink plenty of water to avoid becoming dehydrated.

The warmth will trigger a thaw that reaches into the high country of the Northwest and will have streams and rivers swollen and moving at a swift pace.

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"People are urged to keep in mind that temperatures in lakes, rivers and streams remain low enough to cause cold water shock," Duff said. "Never head out onto a body of water alone or without a life jacket."

Since little rain has occurred over the region as of late, a large portion of Washington and parts of Oregon and Idaho are experiencing abnormally dry conditions, according to the U.S. Drought Monitor.

People should use caution with outdoor power equipment and open flames where dry brush remains from the winter and green-up has not yet occurred this spring.

Southwestern US to get some natural air conditioning

Meanwhile, cool air aloft will allow clouds, showers and locally gusty thunderstorms to form over the Southwest. The cool air aloft will limit the amount of warming in this region.

SW Weekend Storms Static

In some of the highest elevations, snow may fall. During Wednesday night and Thursday morning, people in Colorado were treated with a May snowfall even as the pattern was just developing.

The unsettled pattern in the Southwest can also trigger isolated incidents of both flash flooding and dust storms.

"This is not the time of the year to expect such conditions," Thompson said. "It is more common for chaotic conditions like this when the monsoon kicks in during June and July."

The southwestern U.S. monsoon occurs when a persistent flow of moist air from Mexico produces high humidity, which triggers showers and thunderstorms on a daily basis.

Hikers should keep alert for surges of water through the canyons and arroyos, or typically dry river beds, and move off the ridges during the midday and afternoon hours to reduce the chance of being struck by lightning.

Motorists should be prepared for sudden changes in visibility due to blowing dust.

The wet weather may benefit parts of New Mexico and northeastern Arizona, where abnormally dry conditions have evolved into drought in recent weeks, according to the U.S. Drought Monitor.

During next week, while the Northwest will stay rather warm, the Southwest is forecast to trend sunnier and warm up.


Download the free AccuWeather app to see the temperature forecast and the prospect for rain in your area. Keep checking back for updates on and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.

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