A major storm system is bringing early-season snow, heavy rain and severe thunderstorms to the US this weekend and into early next week.
The storm begins in the western US this weekend, bringing with it the first significant snowfall of the season to the Intermountain West.
“The stretch of unusually warm and dry October conditions will come to an abrupt end today as a potent cold front brings wind, rain, significant mountain snow, and much colder temperatures with a hard freeze,” the National Weather Service in Salt Lake City said Saturday.
Winter storm warnings and winter weather advisories are in place across eight western states on Saturday where 1 to 2 feet of snow is forecast for elevations above 7,000 feet. This heavy, wet snow will result in hazardous driving conditions and reduced visibility.
This system has already brought cold air, rain and higher elevation snow to the Pacific Northwest since beginning on Friday, which has significantly improved the air quality and fire containment across that region.
Beneficial for wildfires and air quality
On Thursday, Portland, Oregon, and Seattle ranked No. 1 and No. 2 respectively for the worst air quality among the world’s major cities, according to the website IQAIR.
Air quality now has significantly improved across the Pacific Northwest thanks to a strong cold front bringing recent rain and a wind shift over the last 24 hours.
In Seattle, more rain fell on Friday (0.32”) than in the entire months of August and September.
While October records more rain on average than August and September in Seattle, this summer has been particularly parched with less than half an inch of rain from July through September, making that period the driest on record.
A secondary system will be moving into the Pacific Northwest beginning Monday bringing even more rain to the region.
Several wildfires across the region have also been contained over the last 24 hours. On Thursday the total large, active wildfire count across the US was over 50, but as of Saturday morning that number has dropped to 30.
For much of the western US high winds also will be a concern as this major storm system progresses eastward. That means that before any rain or snow arrives winds could increase the potential for fire spread and blowing dust.
“The mild and dry conditions partnered with the high winds will also create fire weather concerns,” the National Weather Service in Denver said. “Blowing dust was added to the forecast grids to the east and south of a line from Denver to Sterling, [Colorado].”
Ten states are under high wind watches and warnings on Saturday where winds could gust as high as 75 mph.
Severe storms for the Midwest
Clashing air masses – cold air settling across the West and warm air in the East – also will provide the ingredients for severe storms across the Midwest and Central Plains on Sunday.
Over 10 million people across the central US and Midwest are under the threat for severe storms on Sunday. A Level 2 out of 5 risk for severe storms is in place and includes Omaha and Lincoln in Nebraska and Sioux City in Iowa. A Level 1 risk is also in place and includes Minneapolis, Kansas City and Des Moines.
These severe thunderstorms will be capable of producing large hail and damaging gusts Sunday evening into early Monday. While tornadoes will not be the main threat, there is still a low possibility for one or two in this region.
The rain, however, will be beneficial for central US states such as Oklahoma, Texas, Arkansas, Missouri and Kansas, which have been experiencing worsening drought conditions over the last several weeks.
“Widespread beneficial rainfall is forecast Monday through Tuesday across the region. Average amounts of 1 to 3 inches with locally higher amounts are currently forecast,” said the NWS office in Tulsa, Oklahoma.
One hundred percent of the state of Oklahoma is under drought conditions with Tulsa currently in the extreme category.
A Level 2 out 4 for risk for excessive rainfall was issued for portions of Oklahoma, Arkansas, southwestern Missouri and northeastern Texas on Monday where flash flooding will be possible.
Since the area has been so dry, “the expectation is that the rainfall should generally be beneficial rather than problematic,” the Weather Prediction Center also noted.
The heavy rainfall will also be welcome across the Mississippi River Basin starting Monday, which is dealing with historically low water levels over the last several weeks.