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Huge, dust-filled tornado awed storm chasers in Texas on Monday

More severe storms are forecast to erupt on Tuesday in the Lone Star State

Large tornado seen in Morton, Tex., on Monday. (Gary Mann)

A giant tornado, packed with dust, spun up in rural northwest Texas on Monday, amazing storm chasers. The massive wedge-shaped funnel formed near Morton, about 50 miles west of Lubbock, just before 7 p.m. local time.

Storm chasers surrounded the dark, wide and menacing twister, gathering footage from different angles.

Many were in disbelief.

“Sill gathering my jaw on this one,” tweeted @Tornado_Steejo.

“One of the greatest spectacles I’ve ever witnessed,” tweeted @eMDe_Photo

The National Weather Service did not report damage from the twister, which churned over open fields.

How the tornado formed

The tornado’s origins can be traced to two messy rotating thunderstorms or supercells that developed shortly after 5 p.m. in west Texas. A severe thunderstorm watch was in effect, the risk of significant tornadoes deemed “very low.” It did not appear that ingredients necessary for twisters would overlap particularly well, and moisture was rather limited.

However, the northernmost storm was able to take advantage of more readily available shear or turning of winds with altitude, and began to spin.

The northern cell abruptly weakened, however, as the southern cell began taking over. That’s because it was blocking the northern cell’s inflow, or supply of warm, humid air. There was just enough moisture that the southern cell began to morph into an intense supercell with baseball-size hail in the course of barely 30 minutes.

The Lubbock office of the Weather Service first issued a tornado warning for the storm at 6:50 p.m., cautioning that a storm capable of producing a tornado and hail of three-inch diameter had developed. At 7 p.m., it confirmed a tornado was on the ground six miles north of Morton. At 7:09 p.m., it described the twister as “large and extremely dangerous.”

The twister probably grew up to a half-mile wide.

If you were more than a mile away from it, however, odds are you didn’t see it. That’s because of the ongoing drought in Texas. Inflow winds spiraling in to feed the storm kicked up considerable dust that reduced visibility. Nearly 30 percent of the Lone Star State is under a top-tier exceptional drought, according to the U.S. Drought Monitor, including the zone where the tornado formed.

The Weather Service continued to issue warnings for the tornado until 9:30 p.m., when the parent storm was less than 30 miles west of Lubbock.

Tuesday’s storm risk

About 20 million people in Texas face a substantially elevated risk of severe thunderstorms Tuesday, according to the Weather Service’s Storm Prediction Center. Dallas is in a level 3 out of 5 risk zone for severe storms, while Houston, San Antonio, Austin and Lubbock are in a level 2 risk area.

“Numerous thunderstorms are expected from west-central Texas into the ArkLaMiss region, some of which will produce hail, damaging winds, and a few tornadoes,” the Storm Prediction Center writes.

The storms are being triggered by a developing system over the Southern Plains that will drag a cold front through Texas on Tuesday night. Numerous storms are forecast to erupt in western and Central Texas on Tuesday evening before sweeping through eastern Texas overnight.

The storm risk, albeit somewhat muted, will shift to the central Gulf Coast states north to southern Wisconsin and Michigan on Wednesday.

More scenes of the Morton tornado