|November 11 2022|
Western U.S. Winter Storm to Northern Plains Blizzard: (11/7 - 11/11)
By: Bryan Jackson, WPC Meteorologist
A winter storm that worked its way south off the Pacific Northwest Coast November 7 and 8, turned northeast across the Intermountain West on the 9th, and crossed the Northern Great Plains on the 10th as a Blizzard and Ice Storm over the Dakotas and northern Minnesota. An upper low tracking southeast from the North Pacific stalled over Vancouver Island by 00Z on Nov 7, persisting there into the 8th when a reinforcing shortwave trough swinging around the west side dislodged the low and sent it tracking south off the Pacific Northwest Coast, reaching the coastal border of Oregon and California by 00Z on the 9th. This potent system had low height anomalies at 500mb of over three standard deviations from the mean for Northern California. The low then turned inland as it occluded and weakened and began lifting northeast from northern Nevada later on the 9th. The low then crossed the northern Rockies, reaching the central border of Montana and Wyoming by 12Z on the 10th. The upper low then re-strengthened as it pushed northeast across the Dakotas and northern Minnesota, as the surface low tracked over southern Minnesota. The low occluded over northern Minnesota and Wisconsin and had weakened substantially by 12Z on the 11th.
The deep low that stalled over Vancouver Island allowed Pacific moisture to wrap around the system, pushing over the Cascades and cooling both as it lifted north from the Columbia Basin over the mountain ranges of northern Washington and from approaching the cold core low. This prolonged setup allowed repeating heavy snow with 1 to 2 feet reported in 48 hours ending 12Z on Nov 8 in the eastern Cascades and Okanagan Mountains with estimates of 3 or more feet in remote higher terrain. Due to higher snow levels farther south, the Oregon Cascades received an estimated 6 to 12 inches of snow through this time.
The trough around the stalled low expanded across the Northwest Nov 7 and 8 with impulses and minor shortwaves bringing mountain snows with generally 10 to 20 inches reported in 48 hours ending 12Z on the 8th from the ranges of Northeast Nevada, central and eastern Idaho, to the ranges in and near Yellowstone. An additional 10 to 20 inches then fell at higher elevations of similar locations in a 48 hour period ending 12Z on the 10th as the main low tracked over the Intermountain West.
As the reinforcing wave off the Pacific focused the low farther south off far northern California on the 8th and then shifted inland into the 9th, a prolonged fetch of Pacific moisture was lifted over the Sierra Nevada with 2 to 4 feet of snow reported along the length of the High Sierra over a 48 hour period ending at 12Z on the 9th. As the trough amplified over the West Coast on the 8th, surface high pressure strengthened to around 1035mb over the western Canadian Prairies and sent cold air southeast over Montana and the Dakotas which stalled along a front over the eastern Dakotas and northern Minnesota by 12Z on the 9th.
With the northern Plains primed with cold air north of the boundary, the approaching upper low and upsloping northeasterly flow from the Canadian High allowed areas of snow began to expand over eastern Montana around 00Z on the 10th. Over the next several hours, a surge of low level, Gulf of Mexico-sourced moisture moved up and over the stationary boundary which by 12Z had a 1003mb surface low over southwest Minnesota. This set the stage for moderate to locally heavy freezing rain to lift from central South Dakota to the southeastern corner of North Dakota from about 00Z to 10Z on the 10th where a wide swath of a quarter to half an inch of ice glaze reports were made.
Farther north, the column was cold enough for all snow, so the precipitation bands became heavy snow as they reached northwest South Dakota and spread across nearly all of North Dakota. The snow bands then pivoted over central North Dakota as the parent surface low lifted north-northeast over Minnesota through the 10th into the 11th. This resulted in the maximum snowfall area of 18 to 24 inches in central North Dakota centered on the Bismarck-Mandan area. With the strong pressure gradient between the high centered over Saskatchewan and Manitoba and the Minnesota low, winds increased with gusts over 35 mph and blizzard conditions were reported across much of northeastern North Dakota where 6 to 12 inches of snow were reported. Generally 5 to 10 inches of snow fell in far northwest Minnesota and a secondary area of freezing rain occurred in the Arrowhead and Boundary Waters portions of far northeast Minnesota where one to three tenths inch of ice glaze were reported.
Most of the snow that fell in the Pacific Northwest during this event was in remote higher elevations with limited impacts besides restricting travel over mountain passes and requiring snow chains. The heavy snow across terrain in California was more impactful, particularly for the higher elevation road passes there. The Central Sierra Snow Laboratory in Soda Springs, CA and near Donner Pass reported 34.3” storm total snowfall ending on November 9. Many road closures and multi-car collisions were reported through the storm in and near California mountain passes.
While reports of up to 24 inches were reported around the Bismarck area, the official storm total at the airport was 17.1 inches which is the 6th highest two-day snowfall for Bismarck with records dating back to 1886. 17.0 inches fell on the calendar day of November 10 which is second only to 17.3 inches from April 14, 2013 for the one-day snowfall record.
“No Travel” advisories were issued by the state for most of North Dakota for the 10th and 11th with sections of Interstate 94 and major U.S. Highways closed at times due to the combination of heavy snow rates of 1 to 2 inches per hour and strong winds blowing and drifting snow. Travel was impossible in many areas of the state on the 10th. Blowing and drifting impacts continued into the 11th, though since that was Veterans Day, many further impacts were mitigated somewhat as roads slowly reopened and advisories were lifted that day. Power outage reports during the storm in North Dakota were generally limited. However, thousands of customers were without power in the heavy freezing rain swath in South Dakota due to power lines coming down.
On a final note, most of the Intermountain West and Dakotas are in moderate to severe drought, with extreme drought noted for much of California. So this precipitation, though wintry and impactful, was ultimately beneficial as an early season storm for many affected areas eager for precipitation.