Heightened fire danger to contrast mountain snow, chilly air in western US into Friday

Kyle Elliott

Another storm system will pound the western United States with rain, mountain snow, unseasonably chilly air and gusty winds into late week.

Residents will need to keep jackets and sweatshirts on hand as temperatures resemble those more typically experienced during the middle of October.

High temperatures will be no better than the 60s in the Interstate 5 corridor from Seattle to Portland, Oregon, and the valley regions of the northern Rockies at midweek. Highs in the 70s and 80s will be more common across the Central Valley of California.

Temperatures in the higher terrain will be significantly lower than those in the valleys and are forecast to be low enough to allow some snow to fall.

"Snow levels will dip down to around 7,000 feet in Washington and Oregon, but the snow is not expected to cause many problems," according to AccuWeather Senior Meteorologist and western U.S. blogger Brian Thompson.

Some snowflakes may also reach I-80's Donner Pass, as well as areas in Montana, Wyoming and Utah, that were hit with snow last week.

With the high September sun angle and marginal temperatures, any snow is not expected to stick to roadways and will just serve to remind skiers and snow enthusiasts that the winter season is not too far away.

"It is possible that several inches of snow will fall on non-paved areas at and above some of the passes," AccuWeather Senior Meteorologist Alex Sosnowski said.

In addition to the snow, more rain will soak the Pacific Northwest through Wednesday. This region has already received more rain than usual during the first half of September.

Through Sept. 17, both Seattle and Portland have received more than 2.2 inches of rain, which is more than what they typically get for the entire month.

"There could be some pockets of heavier rain, especially from the Olympic Peninsula of Washington down to the coastline of Northern California, where over an inch of rain may fall in spots through Wednesday," Thompson added.

On Monday, downtown San Francisco received measurable rainfall for the first time since May 26. For San Francisco International Airport, it was the first measurable rainfall since May 21.

While the rain may cause travel delays, spoil outdoor activities and make carrying the umbrella to work a necessity through Wednesday, it will be largely beneficial since much of the Pacific Northwest was still in a moderate to severe drought on the latest U.S. Drought Monitor issued Sept. 12.

Meanwhile, the main impact from these storm systems across the Southwest and Four Corners region will be to significantly stir up the wind, leading to an enhanced risk of wildfire development and spread.

There are dozens of wildfires still burning across the West, and the latest onslaught of gusty winds will only hamper firefighting efforts and lead to erratic, unpredictable fire behavior.

Thompson said that strong winds are on tap over Wyoming, Colorado, eastern Utah and northern Arizona into Thursday.

Wind gusts of 40-50 mph will be common and could cause rapid spread of any wildfires triggered by lightning from thunderstorms.

Campers and hikers are reminded to thoroughly extinguish cigarette butts and campfires in order to avoid the risk of igniting a new blaze.

Although there are also many blazes currently burning in the northern Rockies, the cool and showery weather should help firefighters get the upper hand on these blazes and prevent the development of new wildfires.

By the end of the week, drier and more temperate weather should return to the majority of the West, giving residents a reprieve from the active pattern.