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After four hellacious, destructive days, the onslaught of severe thunderstorms and tornadoes that clobbered the American Great Plains is pausing. Storms broke out Thursday and were followed by back-to-back high-end tornado outbreaks Friday and Saturday. More severe storms hit Texas, Oklahoma and Arkansas on Sunday.

Friday’s outbreak of twisters in eastern Nebraska and Iowa killed one person, and at least four people died in Oklahoma on Saturday night. The pair of outbreaks demolished neighborhoods and left communities forever altered.

Meanwhile, more severe weather is in the offing after Monday’s hiatus. Areas from northern Texas to southern Minnesota could experience powerful storms on Tuesday and Wednesday.

Let’s break down what stood out the most about the Thursday-to-Sunday outbreak:

Over 140 tornadoes were reported over four days

We know that well north of 100 tornadoes touched down between Thursday and Sunday across the central states, but the great majority were on Friday and Saturday.

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Only 10 tornadoes — mostly brief “landspouts,” which form differently from conventional tornadoes, spun up on Thursday, mostly between eastern Colorado and central Oklahoma. But Friday bore witness to 88 reported tornadoes — the majority in eastern Nebraska and southwestern Iowa, with an additional 42 on Saturday, mostly in Oklahoma. A pair of tornadoes also struck Sunday — one each in Oklahoma and Arkansas.

These tornado counts are preliminary as storm surveys are still underway, and it will take a few days for National Weather Service offices to determine final numbers. (Sometimes twisters are double-counted, so initial report totals can be overestimates.)

The swarm of tornadoes kept forecasters at the Weather Service busy. The agency issued over 250 tornado warnings on Friday and Saturday alone.

At least eight tornadoes reached EF3 or higher intensity

Tornadoes are rated on the 0-to-5 Enhanced Fujita (EF) scale. It will take the Weather Service another day or two to finalize EF ratings as well as determine path length and width.

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However, the agency has already confirmed that at least eight tornadoes reached EF3 or higher strength — meaning they were intense with winds of at least 136 mph:

• Marietta, Okla.: Marietta is in the far south-central part of Oklahoma on Interstate 35, where a violent tornado carved a path across the highway and ravaged a Dollar Tree distribution center. The Weather Service announced Monday afternoon that the initial EF3 rating assigned to the twister had been upgraded to a “low-end EF4.” It killed one person and had peak winds of 165 to 170 mph.
• Sulphur, Okla.: Sulphur was hit by a major tornado and then threatened by another on Saturday night. The Weather Service has confirmed the tornado, which killed one person, was at least an EF3, with peak winds of 160 to 165 mph.
• Holdenville, Okla.: This twister, which killed two people, was rated EF3 with peak winds of 140 to 145 mph. It had a maximum width of 1,760 yards.
• The large tornado that struck Bennington and Elkhorn in Nebraska on the northwestern side of the Omaha metro area was rated EF3. It had winds up to 165 mph and was 1,600 yards wide.
• A tornado that struck the northeast side of Lincoln, Neb., was rated EF3 with peak winds of 158 mph. The twister, which injured three people, was 700 yards wide.
• The tornado that struck Eppley Airfield, Omaha’s airport, reached a peak intensity of EF3 with winds up to 152 mph northeast of the airport, according to the Weather Service. At the airport, “the tornado destroyed several aircraft hangars and flipped several untethered executive aircraft, producing EF-2 damage,” the Weather Service wrote.
• A tornado in southern Pottawattamie County, Iowa, just to the east of Omaha near the border with Nebraska, was rated EF3, with peak winds of 145 mph.
• The tornado that tracked through Harlan, Iowa, was rated EF3, with peak winds of 160 mph. The wedge-shaped tornado, which killed one person and injured three, reach a maximum width of about a mile.

Data from a mobile Doppler radar unit found that the Harlan twister had winds up to 224 mph. Such winds are equivalent to what is expected from an EF5 tornado, but the twister did not receive such a rating because those winds were detected above the ground. Furthermore, the EF scale is a damage scale — not a wind scale. Experts surveying the damage would have needed to find evidence of EF5 destruction to assign such a rating — which only happens in less than a tenth of a percent of all twisters.

Semi trucks were blown and thrown

Common amid the outbreak were incidents of semi trucks being blown or thrown by tornadic winds.

One semi truck was blown off the road between Seward and David City, Neb., by strong wraparound winds on the western side of a tornado. A storm chaser traveling toward the tornado narrowly escaped death and swerved at the last minute to avoid the incoming toppling truck head-on, and instead was shoved by the truck up an embankment.

WATCH as a semi gets swept and thrown off the road between Seward and David City, Nebraska as a tornado – briefly invisible – crosses the road.

Condensation funnel or not, PLEASE seek shelter during warnings.

On a day like today, it may very well save your life. @MyRadarWX pic.twitter.com/60GRTW45pw

(I myself was about 150 feet to the south and watched that unfold. See above video.)

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A semi trailer also appeared to fall out of the sky onto Interstate 35 in Marietta, Okla., on Saturday night.

Forecasts saved lives

The toll of five tornado fatalities, while tragic, was relatively low compared to past outbreaks that produced 100-plus tornadoes.

Part of the reason? Good forecasts so that people were warned and ready.

The Weather Service’s Storm Prediction Center highlighted the potential for tornadoes in central Oklahoma on Saturday six days in advance. On the morning of the event, it drew a Level 4 out of 5 risk for violent storms in the zone where most of the destructive tornadoes occurred.

Once tornadoes began to form, advance warnings from the Weather Service office in Norman, Okla., provided plentiful lead time, allowing residents adequate time to seek shelter.

Friday’s forecast for tornadoes in eastern Nebraska and southwestern Iowa was similarly prescient in highlighting the zone at greatest risk for violent storms (although an argument can be made that the risk level should have been higher than Level 3).

Weather Service offices Hastings, Neb., Omaha and Des Moines also provided ample lead time for the tornadoes as they formed. In Elkhorn, Neb., residents had 34 minutes of warning.

Jason Samenow contributed to this report.

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