Robust storm barreling into Northwest US to usher in rain, gusty winds

AccuWeather meteorologists say that the upcoming days across the Northwest will feature rounds of rain, thunderstorms and gusty winds as a storm advances inland. Days of rain, becoming heavy at times along the coastline, will elevate the risk for flash flooding from beach locations like Port Orford, Oregon, to La Push, Washington.

"The start to June in the Pacific Northwest will be unusually cool and wet, with the heaviest surge of rainfall occurring across the region Sunday into Monday," explained AccuWeather Senior Meteorologist Dan Pydynowski.

Through Tuesday, many locations in western Washington and Oregon can receive between 1 to 3 inches of rainfall. However, upslope regions can pick up locally higher amounts of up to 4 to 4.5 inches. Strong winds blowing along the shoreline and heavy rain can result in rough surf and challenging marine conditions.

"For the month of June, the historical average rainfall in Seattle is only 1.45 inches. Through Monday, Seattle may receive its entire monthly average of rainfall in a 24- to 48-hour timespan as a general 1 to 2 inches of rain will fall across the metro area," detailed Pydynowski.

Energy advancing inland to northern Idaho and much of Montana on Monday will encourage the development of thunderstorms. Across Montana, any thunderstorms that develop can bring gusty winds and even small hail as they evolve across the state.

By Monday afternoon, there could even be rumbles of thunder for places closer to the Pacific Coast like Portland, Oregon, and Seattle. Storms can bring pockets of downpours, which could interrupt travel and cause slowdowns.

This round of incoming rain and storms is not exactly typical for the Northwest this time of year, forecasters note.

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"Though people think it is "always raining" in Seattle and the Northwest, that is really not true. The months of June, July and August are typically quite dry in western Washington," added Pydynowski.

Through early week, the stormy pattern will briefly usher in cooler conditions to the Northwest, prompting snowflakes to spread across area mountain peaks as the influx of moisture continues.

"As cooler air moves in Monday, snow levels in the Washington Cascades can fall as low as 5,000 to 5,500 feet. Snow levels Monday will remain just above the level of Stevens Pass, so road travel will not be impacted by wintry conditions," stated Pydynowski.

Although it is not uncommon for snow to occur in the highest elevations of the Rockies and Cascades in June, it will be notable how much that snow levels will decline over the upcoming days. Pydynowski added that some snow may mix with the rain as low as Stevens Pass, but pavement should remain just wet at Stevens Pass. Nonetheless, the snow levels will be impressively low for early June.

From Tuesday through Friday, the jet stream pattern in the upper levels of the atmosphere will shift northward, ushering in warm air from the south. As a zone of high pressure strengthens across the western states, temperatures will rise into the 80s, 90s and even lower 100s Fahrenheit.

Locations like Sacramento, California, are expected to challenge the daily record high temperature of 103 F by Tuesday, with a current forecast that would match the record set in 1935. Additional locations across the San Joaquin Valley will contend with matching or breaking daily records as the week continues.

While places closer to the coast, like Los Angeles and San Francisco, are projected to have highs in the 60s and 70s, locations farther inland like Las Vegas and Phoenix will scorch for much of the week with highs soaring above the 100-degree mark, with temperatures topping 110 degrees in both cities by the end of the week.

As the storm dampening the Northwest tracks inland and eventually reaches the Midwest, forecasters say that intense winds will flare up. Wind gusts can reach speeds of 30 to 50 miles per hour at times, with higher speeds possible across the foothills.

Winds of this speed can bring trees and branches down and make travel difficult. Due to the widespread nature of this wind event, strong gusts are expected to continue behind the path of the storm. The risk for power outages is a growing concern across the region.

By Wednesday and Thursday, gusty winds will shift across areas of the Midwest. By midweek, cities like Fargo, North Dakota; Sioux Falls, South Dakota; and Minneapolis will be at risk for strong wind gusts higher than 30 mph.

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