Winter Storm

4 Jaw-Dropping Facts About Winter Storm Ulmer

At a Glance

Winter Storm Ulmer underwent bombogenesis on Wednesday and reached a record-breaking pressure.
Ulmer produced wind gusts over 90 mph in few spots.
Blizzard criteria was met in at least eight locations and four states.
Ulmer also resulted in record flooding in some areas due to rain and snowmelt.

Winter Storm Ulmer was an impressive and memorable storm for several reasons, including its record low pressure, strong wind gusts, blizzard conditions and record high river levels.

(MORE: Winter Storm Central)

We examine each of those factors below:

Ulmer Underwent Bombogenesis and Broke a Few Pressure Records

Winter Storm Ulmer was a massive low-pressure system that became a bomb cyclone on Wednesday, March 13. A bomb cyclone refers to a strengthening area of low pressure that undergoes bombogenesis, meaning its minimum surface pressure drops at least 24 millibars in 24 hours or less.

Ulmer dropped 26 millibars in 16 hours, achieving bombogenesis, when its central pressure dropped from 994 millibars around 8 p.m. MDT March 12 to 968 millibars around 1 p.m. CDT March 13.

The central pressure of Winter Storm Ulmer reached 968 millibars on Wednesday afternoon.

Unofficial all-time low-pressure records were set or tied in at least four locations, Pueblo, Colorado, Alamosa, Colorado, Amarillo, Texas, and Clayton, New Mexico.

Ulmer Brought Widespread Powerful and Damaging Winds

When the central pressure in a storm system decreases, winds increase and when the pressure drop is rapid and reach levels as low as Ulmer did, very strong wind gusts often occur. This was the case on Wednesday in the Plains.

In Texas, San Augustin Pass reported a gust of 104 mph and Pine Springs measured a wind gust of 103 mph. In the Texas Panhandle, tractor-trailers were blown over and a dust storm developed in West Texas. A wind gust of 100 mph was estimated in Cloudcroft, New Mexico.

A few wind gust reports from Wednesday, March 13.

Colorado Springs reported a gust of 97 mph Wednesday afternoon, while winds gusts up to 80 mph were observed at Denver International Airport.

Wind gusts over 85 mph were also reported in western Kansas and western Nebraska.

Blizzard Criteria Was Reached in at Least 8 Locations, 4 States

Blizzard conditions were observed in many locations where it snowed.

To be considered a blizzard, winds must frequently gust to at least 35 mph and considerable falling or blowing snow must reduce visibility to a quarter mile or less for at least three hours.

At least eight locations met that criteria Wednesday. Two spots that reached official blizzard criteria in Colorado (Denver and Colorado Springs), two locations in Wyoming (Cheyenne and Torrington), three places in Nebraska (Alliance, Valentine and Sidney) and one in South Dakota (Pierre).

A few locations in the Dakotas will also likely reach blizzard criteria Thursday.

Contour on the map is estimated snowfall totals from March 12-13.

Blizzards cause treacherous travel. Hundreds of miles of interstates were closed Wednesday, which left more than 1,000 drivers stranded in Colorado.

Record-High River Levels Resulted in Major Flooding

Milder temperatures surged northward ahead of Winter Storm Ulmer, which had two effects. One was to allow snow that was already on the ground to melt and for ice on rivers to break up and the other was that additional precipitation fell in the form of rain.

This caused flooding as river levels rose late Wednesday into Thursday.

At least six locations set record crests in parts of Iowa, South Dakota and Nebraska with more than 20 river gauges in major flooding.

The blue, purple and pink contour shows estimated snow depth, while the yellow contour shows mild temperatures. The purple circles and diamonds are river gauges at major flood levels.

Many evacuations were issued, including a third of the 24,000 residents in Norfolk, Nebraska, on Thursday due to concerns of flooding as the city's levee system was near its top.

Flooding concerns may linger into next week as rivers, creeks and streams are expected to rise in parts of the Plains and upper Midwest.