Drastic Change to the Weather Brewing in the Pacific Northwest

Posted: June 18, 2023 6:39 am

A raw and wet weather pattern is setting up across the northwestern corner of the U.S. in the coming days, making it feel more like the middle of the spring rather than the start of summer. Here is what you can expect with this forecast.

Arrival of New Storm System Sends Mercury Falling in the Northwest

The arrival of cool temperatures will be even more jarring for a part of the country that has enjoyed warm readings that were well above the historical average over the last few weeks.

Unfortunately for those who were ready to welcome summer for good, a new storm system is moving in from the Pacific Ocean and ushering in unseasonably cool temperatures and loads of moisture. The temperature may even fall low enough in the higher terrrains to generate some light snow.

The steady rain showers will fire up across the coastal areas of the Pacific Northwest early Sunday. While the day will start mostly dry for Seattle, persistent rain showers are forecast to develop by later in the day. By the afternoon hours, the rain will have spread into interior portions of Idaho and Montana.

Rainfall amounts across the region will be moderate on Sunday with no concerns about flash flooding.

The rain is predicted to linger along the coast to start the work week. The moisture will become more intense in the southern corner of Washington state and down the Oregon coast on Monday.

Forecast for the Higher Terrains Includes Thunderstorms and Possibility of Snow

A chance of thunderstorms is possible for the Cascade Mountains and across the northern Rockies by the early part of the week. This higher terrain is most likely to see the heaviest rain out of this weather maker.

The temperatures may cool enough to support the development of light snow on Monday evening through night in parts of Idaho and western Montana.

You can expect the snow levels to dip to about 5,000 feet. Some of the most traveled mountain passes may see a mix of rain and snow. Be sure to check the road conditions before heading out over the passes.

The rain is good news for parts of the region that have been grappling with building drought conditions. According to the latest data release by the U.S. Drought Monitor, much of central Oregon is under the classification of a severe drought.

Record Low High Readings Could be Challenged

Significantly cooler temperatures will accompany the surge of moisture. The mercury will drop from historical averages on Saturday to about 10 degrees under these readings on Sunday as the clouds and rain showers build.

How cold will it be? Some cities will challenge record lows in Washington and Oregon by Monday with readings up to 15 degrees below normal for the middle of June. Generally, temperatures will struggle to get out of the low 60s in areas west of the Cascades. This includes the major cities of Seattle and Portland.

The record low for a high temperature in Seattle on June 19 is 57 degrees, dating back to 1916. While it is likely that the Emerald City will climb above this reading, it may be close. The record low high in Portland for this same date is 61 degrees.

The higher elevations should brace for colder temperatures. Areas such as Snoqualmie Pass in Washington will land in the upper 40s for a high on Monday. High readings across the Columbia River Basin on the other side of the mountains are forecast to hover in the upper 60s.

While these temperatures will certainly be warmer than those areas west of the Cascades, it will still be below the normal readings.

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