|February 15 2023|
Four Corners Region Through Great Lakes Winter Storm: (2/13/23 - 2/16/23)
By: Bryan Jackson, WPC Meteorologist
Consecutive upper-level low pressure systems produced heavy snow over the Four Corners states February 13-15 with subsequent cold. The first system also produced an area of blizzard conditions over a portion of the northern Great Plains with the second system producing a mostly narrow swath of heavy snow from the south-central High Plains through the Great Lakes February 15-16. In addition, heavy snow fell February 13-14 in terrain of the Pacific Northwest, the northern Rockies, as well as over far northern Maine on February 17.
A particularly active stretch of this winter began on February 10 as low pressure developed along the Pacific Northwest coast which shifted south down the West Coast through February 12 where it became cutoff along the southern California coast. Only light precipitation occurred along the West Coast from this low due to Pacific moisture being generally kept offshore with the track. The descent of an upper trough over the interior Pacific Northwest February 13 allowed the first low to eject east with it crossing the Four Corners states and southern Rockies from February 13 into February 14. Subtropical Pacific air, drawn across Mexico, surged ahead of this low and heavy snow fell over the high terrain in proximity to the Four Corners including the San Juans and Sangre de Christos of Colorado and New Mexico which received 1 to 2 feet. This first low was rather potent as it tracked northeast over the central Plains on February 14 with central surface pressures generally below 990mb. Mild conditions led to some rain on the southern Great Plains, but the low drew in an Arctic cold front as it tracked over the Upper Midwest late on the 14th. Only a few inches of snow fell over the eastern Dakotas into Minnesota on the night of February 14, but this combined with 60 mph led to blizzard conditions. This Arctic-sourced blast of cold air swept down the Plains on February 15 ahead of the second low and set the stage for snow over the central Plains through the Midwest on February 16.
The interior track of the upper trough brought a strong feed of Pacific moisture inland over the Pacific Northwest through the northern Rockies. Low heights over Washington and Oregon led to snow levels generally around 2000 feet, and heavy snow both on the coastal ranges and the Cascades where 6 to 12 inches fell from late on February 13 into February 14. Farther inland a narrow band of heavy snow set up across much of southern Montana where 8 to 21 inches fell mainly in terrain along and just north of the border with Wyoming on February 14 with the upper trough closing into a low pressure system that shifted south down the eastern sections of the Great Basin. This second low then crossed the Four Corners early on February 15 before ejecting northeast across the central Plains, reaching the Great Lakes late on February 16. Another round of heavy snow fell across the Four Corners states with an additional 6 to 18 inches on February 15 over a broader area than the previous day with heavy snow along the Mogollon Rim in Arizona and all but the northernmost Colorado Rockies. An estimated 18 to 36 inches of snow fell in 48 hours in the higher terrain around the Four Corners including the San Juan mountains.
Lee-side surface cyclogenesis developed downstream of the second upper low over the Texas Panhandle on February 15. Cyclonic flow drew Gulf of Mexico moisture up through the central Plains where with low level baroclinic tightening from high pressure centered over the northern Plains allowed a narrow swath of heavy snow to develop over eastern Colorado early on the 15th which tracked east-northeast over northwest Kansas and southeast Nebraska through the night of the 15th with 6 to 12 inches of snow. The snow bands then trended narrower and weakened over southern Iowa and along the Wisconsin/Illinois border and over the northern half of the Lower Peninsula of Michigan where generally 4 to 8 inches fell through February 16. Finally, on February 17 the low tracked over the interior Northeast with mild conditions and generally rain except for a switch to a wintry mix in central Maine where up to a quarter inch of ice accreted and heavy snow in far northern Maine where 8 to 14 inches fell.
The succession of two storms was impactful in terms of snowfall, wind, and cold conditions especially over the Southwest. The initial wave produced snow squalls over the Four Corners on February 14, which along with high winds and heavy snow, brought several winter impacts to highways in the Four Corners region. This includes a multi-car pileup on I-15 in southern Utah and in Arizona, a 40-mile stretch of northbound I-17 south of Flagstaff was closed on February 14 as well as a short stretch of I-40 near Winslow. The 10 inches of snow that fell in Flagstaff on February 14 contributed to this particularly active season which has featured the most snowfall there in the past 40 years. In the wake of the second wave, the Arctic-sourced air moving in resulted in some sub-zero temperatures and double digit below zero wind chills. Daily low temperature records were set in the Southwest on February 16 including minus 9 Fahrenheit at Flagstaff Pulliam Airport.
Despite only a few inches of new snowfall and little existing blowable snowpack, the powerful winds, gusting over 60 mph, made for potent blizzard conditions in the eastern Dakotas and western Minnesota on the night of February 14 with hundreds of vehicles stranded on I-94 and I-29. Several schools and public entities closed or opened late on February 15.
The narrow-but-heavy stripe of snow over the central Great Plains through the Midwest caused localized school closures on Thursday, February 16 as well as some road concerns such as a multi-car pileup that closed portions of I-35 in Iowa.