at 10:10 AM by Pierce Larkin

Christmas Blizzard Affects Upper Midwest

Yesterday, you likely noticed the unseasonable warmth across the region. Temperatures quickly warmed into the 70s across southern Kentucky, making Christmas feel more like Spring. But why was this; why did it get so warm?

The NWS Climate report shows the record high of 72 degrees yesterday afternoon. h/t NWS Louisville
The NWS Climate report shows the record high of 72 degrees yesterday afternoon. h/t NWS Louisville

Well, off to our west, a strong surface low began to develop on the lee side of the Rocky Mountains. This had a warm front that extended its reach into the southern Ohio Valley, shifting winds to the south at its passage. This occurred yesterday afternoon, and allowed for temperatures to warm quickly here.

Look at that rise yesterday! h/t SPC
Look at that rise yesterday! h/t SPC

This wasn’t the most interesting part of this system, though. This low pressure system formed at the hands of an incredibly dynamic weather system. A deep shortwave trough dug into the western United States, and began to eject northeastward. With strong jet streaks in the mid and upper levels of the atmosphere, a surface low was easily forced. It strengthened as yesterday went on, creating a tight pressure gradient in the Dakotas. In addition to this, the low, mid and upper level dynamics were forcing widespread and intense precipitation across the Dakotas.

The 300 mb jet streak was intense, and the Dakotas were in a prime spot for heavy precip. h/t SPC
The 300 mb jet streak was intense, and the Dakotas were in a prime spot for heavy precip. h/t SPC
The 500 mb jet streak was intense, and the Dakotas were in a prime spot for heavy precip. h/t SPC
The 500 mb jet streak was intense, and the Dakotas were in a prime spot for heavy precip. h/t SPC
The surface low deepened throughout the day, creating the tight pressure gradient that you see here. h/t SPC
The surface low deepened throughout the day, creating the tight pressure gradient that you see here. h/t SPC

The combination between a tight pressure gradient and heavy precipitation ends up yielding a Christmas Blizzard. Winds in South Dakota were gusting in the 60 mph range for four hours consecutively. Precipitation was so intense that lightning was reported in areas of both South and North Dakota. And there was an Ice Storm in northeastern South Dakota, southeastern North Dakota and northern Minnesota.

Visibilities were reduced across much of the region, and travel was absolutely terrible. Check out some of the scenes from the Christmas Blizzard.

Its crazy! The atmosphere was very cool yesterday, and it was awesome to see a storm develop the way that it did yesterday.