Historic 'bomb cyclone' sets off severe storms, flooding, and a 'dangerous' blizzard in central U.S.

Washington Post

An explosively intensifying winter storm centered over the Colorado Front Range continues to unleash a potpourri of extreme weather across the Plains states and Upper Midwest. The hurricane-force low has combined the worst weather of all four seasons into one - from a string of violent tornadic thunderstorms to damaging winds, blizzard conditions and even flooding.

It's a storm for the record books, strengthening from a run-of-the-mill weather disturbance into a historic cyclone in just 24 hours. Its central pressure dropped 33 millibars from Tuesday to Wednesday, meeting the criteria of a meteorological "bomb." The storm made this transformation over land, rather than water, which is rare.

The National Weather Service described it as "incredible" and a "Great Plains cyclone of historic proportions."

On Wednesday morning, the storm's pressure had dropped to the equivalent of a Category 2 hurricane. Hurricane-force gusts hit both Dallas (78 mph) and Denver (75 mph). A storm this extreme was triggering extreme impacts, which are predicted to intensify Wednesday and Wednesday night.

Tuesday began with a funnel cloud whirling ominously over Mesa, Arizona. Tornadoes touched down in Loving, New Mexico, and Hagerman, about 60 miles to the north-northwest.

Storms continued after dark from the Texas Panhandle to the Concho Valley after dark, a possible tornado touching down just northwest of Anton. Baseball-size hail left multiple vehicles destroyed farther south in Ward County along Interstate 20.

The storms congealed into a squall line that blasted east overnight, scouring the Lone Star State with widespread damaging winds topping 70 mph early Wednesday. A gust to 78 mph rocked Dallas-Fort Worth International Airport, the strongest since at least 1995. The winds ripped a roof off an Amazon warehouse near the airport.

Over 150,000 customers lost power in Texas from the violent winds.

More dangerous thunderstorms are in the offing Wednesday. The Storm Prediction Center has designated portions of the lower Mississippi River Valley in an "enhanced risk" zone for severe weather, including eastern Arkansas, southwest Tennessee and the northwest corner of Mississippi.

Winds are also roaring outside of thunderstorms. High wind warnings stretched from New Mexico to Nebraska for gusts up to 60 mph (and 80 to 100 mph at high elevations) while advisories for gusts up to 40 to 50 mph extended as far east as western Tennessee. A wind gust of 92 mph was closed in Glenhaven, Colorado.

Air pressures have been falling steadily while the storm gathers steam. Pueblo, Colorado, saw its pressure sink to 970 millibars, unofficially its lowest on record, on Wednesday morning.

Wednesday afternoon, Dodge City, Kansas, may flirt with its lowest pressure ever recorded - 971.6 millibars, according to the National Weather Service. The last time the city's barometer dipped below 975 millibars was in 1960.

To understand the significance of this record "low pressure," consider a whirlpool generated by stirring your morning coffee. The more intense your stirring, the more pronounced the depression in the coffee's surface. A dramatic dip indicates an intense cyclone, and in parts of Colorado and probably Kansas, the surface of this "atmospheric whirlpool" has dipped closer to the ground there than during any such system in the past.

Meanwhile, cold air surging down from Canada entailed into the backside of the system is leading to a "dangerous" blizzard from northeast Colorado to northwest Minnesota. Blizzard warnings stretch nearly 800 miles.

The clash of seasons has been dramatic in a number of spots, but few more so than Denver. Now under the blizzard warning, the Mile High City hit 62 degrees Tuesday before falling to freezing Wednesday morning as rain transitioned to heavy snow. Six to 12 inches are forecast as temperatures fall through the 20s. Winds were forecast to gust to 70 mph with whiteout conditions and potential power outages.

At Denver International Airport, sustained winds reached 55 mph with gusts 75 mph with heavy snow and visibility under a quarter mile at 11 a.m. local time. The number of customers without power in Colorado was over 80,000 and climbing.

"Travelers across the Colorado mountains and eastern plains should consider canceling travel plans," the Weather Service office serving Denver and Boulder warned. "Be aware that if you go somewhere this morning, you could become stranded."

Farther to the north in southeast Wyoming and western Nebraska into western and central South Dakota, conditions were expected to be more severe with up to one to two feet of snow combined with 50 to 70 mph gusts (and up to 80 mph at high elevations).

On the storm's warmer side, heavy rainfall could lead to flooding from Kansas through the western Great Lakes. The National Weather Service warned of "prolonged, major flooding" along the Missouri River and its tributaries Wednesday and Wednesday night. It said the combination of downpours and rapid snowmelt would probably elevate the river to major flood stage, not cresting until some time after the rain ends.

In eastern South Dakota, Iowa, southern and eastern Minnesota and much of Wisconsin, ice jams were expected on rivers because of the combination of rain, melting snow and thawing temperatures.

The National Weather Service office serving Green Bay, Wisconsin, also warned that the periodic rains falling on a dense snowpack "will add weight to [snow-covered roofs], possibly leading to structural damage."

The sprawling storm system will taper down Thursday, departing into the east and becoming absorbed in larger-scale flow to the north. In its wake, a shot of cold arctic air will descend over the Midwest and Northeast.

First published in The Washington Post

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