A powerful low pressure system moved across the nation’s midsection on December 15th leading to widespread severe weather, Strong winds, and short periods of intense rainfall causing near whiteout conditions. Cold air moving southward on the backside of this low pressure system resulted in snowfall accumulations across west central and north central Nebraska.
The forward speed of this low pressure system was also unusual as it moved from southeast Colorado to northeast Iowa (nearly 1000 miles) over a 12 hour period. To put this in perspective, the average forward speed of surface low was just over 80 mph. Thus, even without the severe weather, the displacement of air ahead of the low pressure would have resulted in wind gusts of 50 mph.
Storm reports across Nebraska were extensive. According to the preliminary storm reports available through the Storm Prediction Center (SPC), a total of 8 confirmed tornadoes have been reported as of 8:00 am Central Standard Time (CST) on December 16th. It is possible that the confirmed tornado count could increase after the National Weather Service conducts on-site storm assessments. The locations that SPC indicate had tornado touchdowns include 3 miles west of Glenvil, 1 miles south of Edgar, 1 mile southwest of Aurora, 2 miles northeast of Marquette, Columbus, 2 miles southeast of Humphrey, Beemer and 4 miles east of Ceresco.
In total, SPC reports that 8 tornadoes, 2 hail and 112 wind reports were captured through their storm report data base. Total storm reports issued from this event included 21 confirmed tornado touchdowns, 19 hail reports and 552 wind reports primarily centered on the states of Iowa, Minnesota, South Dakota, Nebraska, Kansas and Missouri. A graphical representation of the storm reports issued from yesterday through 8:00 am CST can be found in Figure 1.
Damage assessments and reports are still filtering since the severe winds associated with this powerful low pressure system continued for several hours after the system had moved northeast of Nebraska. Preliminary reports indicate widespread tree and limb damage, structural damage to buildings and center pivots overturned and/or destroyed. This is not unexpected considering peak wind gusts reached 93 mph at the Lincoln Airport, 86 mph at the Beatrice Airport, 85 mph at the Grand Island Airport, 83 mph at the Sidney Airport and 81 mph at Offutt Air Force Base.
If there is a bright side to this story, it is that crops had been harvested and non-coniferous trees had shed their summer foliage which likely saved much of the Nebraska from additional monetary losses. The 2020 Iowa Derecho event caused extensive crop, building and grain bin damage when it hit in early August. With grain bins filled from this year’s harvest, damage so far appears to be light in Nebraska, but would have likely been as extensive as experienced in Iowa last summer if this event had come during the second half of this year’s growing season.
Al Dutcher, Agricultural Extension Climatologist, Nebraska State Climate Office