| December 26 2023 |
Christmas & Boxing Day 2023 Winter Storm
By: Peter Mullinax, WPC Meteorologist
Meteorological Overview:
A powerful winter storm produced a white Christmas in portions of the Rockies and Great Plains in 2023, however the snow was accompanied by blustery winds, blizzard conditions, and even significant ice accumulations in the Northern Plains. The storm’s origins began on December 23 as two separate upper-level disturbances; one in the Southwest and another in the Northern Rockies, both of which fostered an extensive area of upper-level divergence throughout the Rockies. At lower levels, the trough in the Southwest worked in tandem with strong high pressure over the Southeast U.S. to direct rich Gulf moisture northward through the southern High Plains. Temperatures were initially on the mild side in the Central and Northern Plains, but an approaching cold front the morning of December 23 ushered in a sub-freezing air-mass into western Montana that would soon spread into the rest of the Northern Plains by Christmas Eve. This atmospheric setup on December 23 led to measurable snowfall in many mountain ranges of the West that stretched as far north as Glacier National Park to as far south as the Sangre De Cristo of New Mexico. By the morning of Christmas Eve (December 24), the 500mb upper-air analysis showed the northern stream disturbance had plunged southeastward into Wyoming and began to interact with the southern stream disturbance that was tracking in the CO/NM High Plains. The southern disturbance had begun taking on a negative tilt, which allowed for a strengthening of the 250-500mb diffluence aloft over the Central Plains. Meanwhile, a strong cold front associated with the northern stream disturbance had moved through the northern High Plains, and deepening low pressure in Kansas resulted in a strong low-level jet in the Southern Plains that directed anomalous moisture northward into the Central and Northern Plains.
What followed was a rapid deepening of the low-mid level circulation center over the Central Plains between the morning of Christmas Eve and Christmas Day. The 850mb low over the Central Plains went from initially becoming a weakly closed low Christmas Eve morning to becoming a robust storm system between Omaha, NE and Kansas City, MO by Christmas morning. While the low-level circulation center was farther east, the 500mb low was still over eastern CO, implying the storm was not yet vertically stacked and still capable of strengthening. In addition, upper-level ridging strengthened over both the West and East Coasts, resulting in the storm being cut-off from the primary jet stream steering flow and causing the storm to stall. Snow would develop throughout the day Christmas Eve, but by Christmas Eve night and into Christmas Day, winds on the western flank of the developing storm system ranged from 40-60 knots and intense snow bands began to form within the storm’s deformation zone. This was suitable for blizzard conditions to envelope areas from central SD on south into northern KS. Farther east, strong warm-air advection at low-levels would over-run the sub-freezing air mass near the surface. This caused extensive areas of ice to ensue over northern SD, southern ND, and southwest MN. By Boxing Day (December 26), the deformation axis advanced farther west into the Black Hills of SD/MT where the heaviest snow would transpire. Periods of prolonged freezing rain continued along the occluded front in southeast ND and northern SD where a melting layer aloft and sub-freezing temperatures at the surface continued to linger. The storm would continue to hover over the Central Plains even into December 27, however with it steadily weakening and the air-mass modifying, snow and ice accumulations would gradually become much lighter.
In terms of snowfall totals, a swath of 6-12 inches of snowfall blanketed northern NE and much of central and western SD with localized amounts over 12 inches. The ice accumulations were exceptional over northern SD and southeast ND where totals ranged from 0.5-1.0”. This late December blizzard produced intense wind gusts in areas with heavy snow as well as max wind gusts ranging, on average, between 50-70 mph with WPC’s final Storm Summary containing a max wind gust of 72 mph at Rapid City Airport, SD.
Impacts:
This winter storm generated widespread travel-related impacts across the Central and Northern Plains over the holidays. At one point, a section of I-90 was shut down according to the Rapid City, SD WFO’s own review of the event. “Much of Interstate 90 was closed for about 12 hours, and even afterwards, no travel was advised, especially in the northern Black Hills”, the Rapid City WFO’s report read. The Aberdeen, SD WFO echoed the same closure in I-90 on Christmas Day stating that the closure even continued “into the morning hours of December 26.” The Department of Transportation for SD posted “No Travel Advised” signs across some state and county roads as well during the peak of the event. According to an Associate Press (AP) article, “On Christmas Day, one person was killed and three others were injured in Kansas, when the driver of a pickup truck lost control on snow and ice and collided head-on with a sport utility vehicle 5 miles (8 kilometers) west of Larned, according to the State Patrol.” The impressive ice accumulations did lead to some power outages across portions of the Sioux City, SD WFO’s CWA, with some localized power outages also occurring where blizzard conditions unfolded. The blizzard conditions also caused flight delays and cancellations. Per the previously referenced AP article, Denver International Airport reported over 530 flight delays and 23 cancellations as of Tuesday afternoon (December 26). Given it was the holidays, schools were not in session, but this winter storm managed to produce numerous travel headaches across the central and Northern Plains, despite giving residents a White Christmas outside their homes.
Link to NWS Sioux Falls, SD's Storm Summary: https://www.weather.gov/fsd/20231225_icesnow_sdiamnne
Link to NWS Rapid City, SD's Storm Summary: https://www.weather.gov/unr/2023-12-25_26
Link to NWS Aberdeen, SD's Storm Summary: https://www.weather.gov/abr/2023ChristmasStorm
Link to WPC's final Storm Summary for this event: https://www.wpc.ncep.noaa.gov/storm_summaries/2023/storm29/stormsum_4.html
