© Sabrina Devers Via Tmx/via REUTERS
A view of a damaged site in Perryton, Tex., Thursday, after the town was struck by a tornado.

A dramatic clash of air masses triggered violent thunderstorms over Texas and Oklahoma on Thursday evening, unleashing tornadoes, large hail and damaging straight-line winds. The ongoing siege of severe weather was expected to continue into the pre-dawn hours Friday.

A destructive and deadly tornado tore through the town of Perryton in the northeast Panhandle of Texas early in the evening killing at least three people according to NBC News and sending 75 to 1o0 people to the hospital.

Joe Puma, a broadcast meteorologist based in Amarillo, tweeted it marked the first deadly tornado in the Texas Panhandle in nearly 20 years.

The twister, captured on video by storm chasers, damaged or destroyed 30 mobile homes, according to Puma. Footage from social media revealed widespread collapsed structures and trees stripped bare of their foliage. Perryton is home to about 8,500 people.

The tornado in Perryton was just one of over 200 reports of severe weather logged by National Weather Service as of 9:30 p.m. Central Thursday, most of them from Oklahoma and Texas but received from as far away as Ohio and Florida. At least 7 tornadoes were reported, most of them touching down near the Oklahoma-Texas border.

Nearly 50,000 customers were without power in the two states according to PowerOutage.us.

The intense storms also produced nearly 100 reports of large hail which grew as large as softballs in Lawton, Okla. around 5 p.m.

As of 9:30 p.m. Central time, the same line of storms that produced the tornado in Perryton was sweeping across central Oklahoma, barreling to the southeast at 50 mph. A severe thunderstorm warning was in effect for Oklahoma City, for 70 mph wind gusts until 10 p.m.

As storms began to congeal in western Kansas and the Oklahoma Panhandle on Thursday afternoon, the National Weather Service issued a tornado watch for northwest Texas and its eastern Panhandle as well as central and western Oklahoma, including Oklahoma City. After the tornado threat eased, it was replaced by a severe thunderstorm watch in effect until 3 a.m. Friday. The Weather Service cautioned wind gusts could reach 75 mph while hail could be as large as two inches in diameter.

Another tornado watch was in effect for central and north Texas, including Dallas, until 10 p.m. Central time.

The storms were being fed by extreme heat and humidity that produced heat indexes of around 115 degrees Thursday afternoon in South Texas. Sauna-like conditions swelled as far north as Dallas which posted its highest humidity level on record.

Thursday’s storm threat followed an outbreak on Wednesday that yielded more than 500 reports of severe weather from Texas to Florida. Hardest hit were southeast Alabama and southwest Georgia, where at least half a dozen tornadoes touched down.

There were scores of reports of large hail, reaching the size of at least baseballs in Arkansas, Mississippi and Alabama. In east central Mississippi, not far from the border with Alabama, there was a report of five-inch diameter hail that, if validated, would be near the state record.

Storms with large hail and tornadoes hit Southeast

What to watch next

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Both Wednesday’s and Thursday’s severe weather events prompted the issuance of rare Level 4 out of 5 severe weather risks by the National Weather Service Storm Prediction Center. They mark the first such outlooks hoisted since April 4, when a widespread severe weather outbreak hit the Mississippi Valley. May, ordinarily peak severe weather season, was unusually quiet.

The ongoing severe weather stems from an exceptionally strong jet stream roaring across the South more characteristic of April than June.

What fueled the storms




© WeatherBell/WeatherBell
Thunderstorms are expected to ride along a warm front lifting into Oklahoma. (WeatherBell)

Low pressure was pushing through the Texas Panhandle on Thursday afternoon. Its counterclockwise circulation lifted a warm front northward to the east. That warm front divided cooler, drier continental air to the north from moisture-rich Gulf of Mexico air to the south. Storms then rode along that boundary like rail cars on a train track.

A belt of fierce jet stream winds aloft, meanwhile, steered storms east-southeast, some growing tall enough to mix that momentum to the surface in the form of destructive straight-line winds.




© WeatherBell/WeatherBell
A belt of strong jet stream winds overhead will provide the momentum that storms will mix to the surface in the form of destructive wind gusts. (WeatherBell)

Extreme heat hazard

Historically speaking, extreme heat kills an average of 10 times more Americans each year than tornadoes. The same hot, sultry air mass that fed severe thunderstorms in north Texas and Oklahoma baked South Texas Thursday.

Heat advisories covered Dallas, Fort Worth, Houston, Austin and San Antonio, as well as Lake Charles, Alexandria, Baton Rouge and New Orleans in Louisiana.

“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors,” advised the National Weather Service. “Young children and pets should never be left unattended in vehicles under any circumstances.”




Predicted heat indexes at 3 p.m. Central time Thursday from the European weather model. (WeatherBell)

The heat wave is forecast to be prolonged.

New Orleans, for example, will see highs in the upper 90s for at least the next 4 or 5 days. Coupled with tropical humidity, heat indexes will hover around 110 degrees. That will pose a particular stress on the elderly and those with underlying health conditions.

In Dallas, heat indexes will be similar. Actual air temperatures will hit the upper 90s to near 100 for each day in the foreseeable future. Overnight lows will only fall into the upper 70s, giving little overnight relief from the heat for those without adequate access to an air-conditioned environment. The same is true in Houston-Galveston.

For those in interior South Texas, heat indexes as high as 118 degrees are expected.

“Extreme heat and humidity will significantly increase the potential for heat related illnesses,” the National Weather Service in Corpus Christi warned. Air temperatures of 103 to 107 degrees are expected into next week.

There appears to be no obvious end in sight for the heat.