Millions of Americans are facing extreme weather whiplash this week — notably in cities including Chicago and Dallas, which were forecast to swing from record highs to wintry lows.

The big picture: Ground stops were temporarily declared at Chicago Midway and O'Hare airports into early Wednesday amid multiple reports of tornadoes, powerful winds and "golf ball-size hail" in the area, as a supercell swept across parts of Illinois and into Ohio Valley.

A strong winter storm was continuing to impact much of the U.S. West, with heavy snow, gusty winds and rain, the NWS noted in its Tuesday night forecast discussion.

Meanwhile, critical fire weather conditions were affecting the Texas Panhandle into Oklahoma. 

    Threat level: In the Midwest and Ohio Valley, there was an enhanced risk (level 3 out of 5) of severe weather, with thunderstorms expected into the overnight hours.

Tornado watches were issued for about 10 million people, including in Chicago. The Kane County Sheriff's Office, west of Chicago, said in a Tuesday night Facebook post there had been multiple reports of damage from a suspected tornado, but no injuries thus far.

In Chicago, which on Monday hit a record 67° Fahrenheit for Feb. 27, a "power-house cold front" was ripping across the area late Tuesday

"with a remarkable temperature drop," noted the NWS' Chicago office in a discussion.

"While the below normal temps Wednesday and Wednesday night will feel harsh coming off the exceptional, record breaking warmth of

Monday and Tuesday, the pendulum will swing right back to spring
through the weekend."

In Dallas, temperatures were set to drop from a high of the mid-90s on Monday to the 50s on Wednesday. Dallas Fort Worth International Airport reached 91°F on Monday — a record high for Feb. 26 and the seventh-earliest first occurrence of at least 90°F in the area, according to the local NWS.

Zoom out: "Much of the nation's weather story through the next 36 hours remains tied to a strong Polar cold front which continues to sweep across the Lower 48," according to the NWS.

"After a period of widespread all-time record breaking warmth yesterday, temperatures across portions of the Northern Plains have plummeted nearly 50-60 degrees behind the front in a stark reminder that meteorological winter is still with us for two more days," the weather agency noted.

A similar scenario was unfolding across portions of the Southern Plains and Midwest. "Widespread record warmth (including some all time records) are forecast ahead of the front before falling off into the 40s and 50s tomorrow," per the NWS. 

This strong cold front was driving critical fire weather conditions across the Southern Plains due to a combination of "very dry, warm, and gusty conditions."

What's next: A "significant winter storm" will hit the West Coast late Wednesday into Thursday, with impacts focused atop the Cascades and Sierra Nevada in California," the NWS said.

"Extremely heavy" snowfall rates exceeding 3 inches an hour would lead to "multiple feet of snow" for higher elevations in these areas, according to the NWS.

A swath of winter storm warnings and watches extended from the Olympics and Cascades southward into the Shastas and Sierra Nevada, as the weather service warned travel conditions would be "difficult to impossible" in the mountains.

In the lower elevations, localized heavy rainfall was expected along the Pacific Northwest and Northern California coastline.

Between the lines: Studies indicate that climate change is increasing extreme weather swings, while El Niño has been another key factor.

Go deeper: February is continuing Earth's record warm streak

Editor's note: This article has been updated with new details throughout.

(The above demonstrates why global warming is no usually referred to as "climate change", because a warmer average temperature changed the thermal dynamics of weather giving us all kinds of extreme weather verging into both hot and cold, not just more heat.)