Significantly Cooler Air and Moisture in the Forecast for the West This Weekend

Posted: October 2, 2023 9:07 am

Winter is on the doorstep of the West Coast, particularly for the higher elevations of the region. While the calendar will read the beginning of October, it will feel more like the middle of November for some portions of the region. Here is a look at this forecast.

Dip in Jet Stream Brings Down Unseasonably Cool to the West

The mercury is forecast to plummet up and down the West Coast this weekend and heading into the first week of October. This chilly weather will feel even cooler with the addition of rain for the lower elevations and measurable snow for the high country. Although the extreme elevations have already seen their first snowflakes of the season, the upcoming weather pattern will bring more significant accumulation to a bigger region.

The unseasonably cool temperatures will come at the hands of a southward dip in the jet stream that is expected to form this weekend across the interior portions of the West. The cooling temperatures will help to pull in moisture from the nearby Pacific Ocean. If this moisture falls as rain, sleet, or snow will depend on the elevation.

Although the West is no stranger to this weather pattern later in the fall season, it is arriving about one month early. The beginning of October is typically one of the driest times of the year for the West.

Who Will See the Rain

The arrival of this storm will bring rainfall of up to a quarter of an inch to the San Francisco Bay Area and up to a half of an inch for Los Angeles. These measurements are more typical of what is seen in early November when the rainy season begins.

Even the desert of Las Vegas was expected to get in on some of this rain action with a slight chance of moisture on Saturday. The Central Valley of California may also experience a few sporadic rain showers that could hamper plans for outdoor activities.

The west-facing lower slopes of the Sierra Nevada expected between 1 and 2 inches of rain. Roads may become slick when the rain first starts to fall as it mixes with oil remnants and other types of debris. Forecasters were not anticipating any widespread travel delays or flooding concerns in these lower and intermediate elevations.

Meaningful Snow Accumulation in the Forecast for Higher Elevations

It could be a different story heading up to the higher elevations. Terrains of about 8,000 feet and up in the Sierra Nevada are forecast to see several inches of new snow. The heavily traveled Donner Pass on Interstate 80 in California may see the flakes fly.

The snow levels are predicted to fall as low as 2,000 feet in some portions of the northern Rocky Mountains throughout Wyoming, Montana, and Idaho. This snow will hold off until the end of the weekend.

While it will be a dry start to the weekend in Salt Lake City, the rain will move in by Sunday and is expected to linger through at least Tuesday. High temperatures will fall from a high of 80 degrees on Saturday to readings in the low 60s on Sunday. The mercury will struggle to get out of the upper 50s on Monday and Tuesday with occasional rain showers putting a damper on the start to October.

Do not be surprised to see snow in the intermediate elevations to the east of Salt Lake City. The Wasatch Range could see snowfall accumulations of 6 inches or higher. The snow will begin to mix with the rain in the ski resort town of Park City by Monday. Temperatures will hover in the mid 40s for highs on Sunday, Monday, and Tuesday in this area.

Chilly Weather Invades Normally Temperate Southern California

It will be much cooler than normal for central and southern portions of California. The unseasonably cool temperatures could even break some records for the coolest high readings on Saturday and Sunday for some cities. For instance, some parts of the interior Southern California valleys may not even hit the 70-degree mark.

The high on Sunday in downtown Los Angeles is forecast to top out at 67 degrees. This is a reading that is more typical of the weather around Thanksgiving. It will be a pleasant day to take a walk down the famed Las Vegas Strip on Sunday with a projected high of just 74 degrees. The temperatures swing from Friday to Sunday in Sin City will be about 20 degrees.

The mass of cool air will move farther inland in the Pacific Northwest when compared to the blast of chilliness that hit the same region earlier in the week. While it will remain dry over the weekend for Seattle, temperatures in the mid 60s will make it feel more like the middle of October.

The southward movement in the jet stream will shift to the east by the middle of next week, bringing more seasonable conditions back to the West Coast. The warmer temperatures will move into the coastal areas on Monday and Tuesday with the interior portions feeling the warmth once again by Wednesday.

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