|April 12 2022|
Northern Rockies to Northern Plains Blizzard: (4/11 - 4/14)
By: Rich Otto, WPC Meteorologist
A historic, long duration snow storm affected the northern Rockies and northern Plains from April 11-14, 2022, with multi-day blizzard conditions observed in eastern Montana, northwestern South Dakota as well as central and western North Dakota. Snowfall totals were in excess of two feet across Montana and North Dakota with one report of 47 inches in western Montana.
The storm system developed as a closed mid-level low entered the Pacific Northwest on April 11. Below average temperatures in place in the northwestern U.S. as the mid-level low entered the region supported light to moderate snow with late season accumulations in Portland, Oregon. The closed low tracked across central Idaho into southern Montana before emerging over the western Dakotas by 1200 UTC April 13. As the closed low crossed the northern Rockies after 0000 UTC April 12, moderate to heavy snow developed over eastern Montana into North Dakota as strong low to mid-level frontogenesis combined with low level warm air advection and ascent via upper level divergence and diffluence. From 1200 UTC April 12 through 0600 UTC April 13, bands of moderate to heavy snow aligned from west to east, or parallel to a low level baroclinic zone from eastern Montana into North Dakota.
The closed mid-level low intensified as it slowly tracked eastward, reaching the North Dakota/Minnesota border on 1200 UTC April 14, with its forward motion slowed by downstream ridging over the eastern U.S. The slow eastward progression of the closed low allowed for periods of heavy snow to persist over western North Dakota, with its 700mb reflection tracking approximately 350 miles over a 36 hour period ending 0000 UTC April 14, allowing a deformation axis to remain nearly stationary over eastern Montana into the western half of North Dakota. At the surface, a tight pressure gradient existed over the northern Plains between a 985mb low tracking eastward across Nebraska while the southern extent of ridging was situated over south-central Canada. The tight pressure gradient allowed for strong wind gusts from eastern Montana into the northern Plains, with gusts peaking between 50 and 70 mph, supporting blizzard conditions with significant blowing and drifting of snow. As the upper low tracked northeastward after 0000 UTC April 14 into northern Minnesota and southern Ontario, snowfall intensity waned over the northern Plains and wind began to subside.
The beginning of the storm produced 1.6 inches of snow at Portland International Airport in Oregon on April 11, marking the latest measurable snow ever recorded at the location since record keeping began in 1941. Prior to this storm, the latest measurable snow at Portland International Airport was on March 25, 1965 with 0.3 inch.
There were a number of impacts to travel due to difficult travel conditions resulting from the blizzard, with blizzard conditions spanning 3 days between April 12 -14 in the northern Plains. A "No Travel Advisory" was issued by the North Dakota Department of Transportation on the morning of April 12 for large sections of central and western North Dakota. Later in the day, a nearly 300 mile long stretch of I-94 was shut down between Glendive, Montana and Bismarck, North Dakota as well as a roughly 150 mile portion of I-90 between Rapid City and Pierre, South Dakota. Numerous accidents were reported as a result of the snow storm and several airports in North Dakota were shut down for multiple days due to the combination of snow and wind. Heavy wet snow and strong winds also contributed to downed trees and power lines which resulted in power outages in North Dakota and South Dakota.
Daily max snowfall records were set at several locations, including 13.9 inches at Billings, MT, 10.0 inches at Bismarck, ND and 11.0 inches at Grand Forks, ND on April 12. Drifts of over eight feet were measured in portions of North Dakota and Minot reported the state's highest accumulation with 36 inches. However, the 36 inch report from Minot was not able to be used to break a 34 inch 3-day accumulation state snowfall record set in Minot back in 1984 as it was not taken at the official climate site in Minot. In the wake of the storm system, numerous record cold temperatures were observed from central Montana into the northern Plains and upper Mississippi Valley between April 12-16.