The storm was dumping snow over the Texas Panhandle at a rate of 2 to 3 inches an hour. Oklahoma also was being hit hard, and parts of Kansas and Missouri were under winter storm warnings.
Almost all roads in the Texas Panhandle were impassable, and whiteout conditions forced the state Department of Transportation to pull virtually all of its snowplows off roads, Texas DOT spokesman Paul Braun said Monday morning.
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On its Facebook page, the weather service posted a video of the wind and snow whipping a U.S. flag outside its Amarillo office.
"If after watching the last video you thought you could still get out and travel, well you haven't seen anything yet!" the Facebook post said.
And later, it followed that up with another indication of how bad things were getting.
"Amarillo Airport just recorded a gust of 65knots/75mph! This is truly a historic blizzard!" the second Facebook post said. "Conditions have NOT improved. Please stay inside and do NOT venture out."
As of noon Central time, 17 inches of snow had fallen in Amarillo, the weather service said in a Twitter post.
For some, the service's warnings didn't come soon enough.
Emergency crews were having trouble reaching drivers who were caught on the roads, Texas Department of Public Safety Trooper Gabriel Medrano said. Cars were in ditches, he said, because drivers couldn't tell where road ended and ditch began.
National Guard units were being sent to help stranded motorists, the Texas DOT said.