Tornado outbreak and floods of April 28 – May 1, 2017

Between April 28 – May 1, 2017, a series of severe weather events affected the Central United States, producing life-threatening flooding and a major tornado outbreak. It formed out of a disturbance in the Southwestern United States on April 28, and caused significant impacts, including a heavy snowstorm in the Rockies, and other types of severe weather. Up to 3 ft of snow fell on the cold side of the system, and up to a foot of rain fell in and around the central parts of the nation.

The most significant and damaging events of the storm unfolded late on April 29, when two large, long-tracked, and powerful wedge tornadoes struck areas near Canton, Texas, the strongest being an EF4. Together, the two tornadoes caused four deaths and many injuries.

Meteorological history
On April 28, a stationary front drifted across the central United States, associated with cloudiness and showers. By 21:00 UTC, a surface low with a central pressure of 1003 mbar developed in central Kansas. Shortly afterwards, thunderstorms erupted along the stationary front, which required the National Weather Service to issue some severe weather watches. A few tornadoes touched down, including an EF2 that caused considerable damage near Cameron, Oklahoma. By April 29, a ridge of high pressure centered over the Atlantic Ocean, this helped focus high levels of atmospheric moisture rising from the Gulf of Mexico along the front, causing immense clusters of heavy rain and thunderstorms to slowly progress eastwards – also known as thunderstorm training. Simultaneously, after deepening slightly to 992 mbar, the elongated area of low pressure was producing heavy snowfall in parts of Nebraska and Colorado, including Denver. Little change occurred over the next six hours as the front moved slightly eastwards; although a squall line was beginning to form, increasing the threat for large hail, damaging wind gusts and a few tornadoes. While the overall setup was not favorable for a widespread tornado outbreak, thunderstorms from earlier in the day left behind an outflow boundary draped across northeastern Texas, resulting in a localized area of enhanced low-level helicity. Deep moisture, high levels of CAPE, and low LCL heights were also present in this area as multiple thunderstorms rode the boundary and dramatically intensified into large tornadic supercells. A violent EF4 wedge tornado developed near Eustace, Texas and passed west of Canton, leveling homes, debarking numerous trees, and killing two people. Two more people were killed by a separate EF3 wedge tornado that passed east of Canton, destroying a car dealership along I-20, tossing numerous vehicles, destroying homes, and causing significant damage further north in the town of Fruitvale. An EF2 tornado also touched down near Log Cabin and dissipated near Eustace, destroying additional homes and a communications tower. Multiple additional weak tornadoes occurred in Texas and in other states that afternoon and evening as well.

Overnight into the early hours of April 30, the activity pushed eastward and a powerful squall line of severe thunderstorms with numerous embedded tornadic circulations swept through the Mississippi Valley. Throughout the day, the low tracked northeast into the Plains and intensified, causing some snowfall in the mountainous regions and in colder places, meanwhile severe weather continued to occur in the South. Forty-two tornadoes occurred across the Southern United States that afternoon and evening, with much of the activity centered in Mississippi. While many of these tornadoes were weak, some were large and wedge-shaped and reached EF2 intensity. One of these strong tornadoes killed one person and caused damage in the town of Durant, Mississippi.

On May 1, another squall line of severe storms developed further to the north. The Storm Prediction Center ended up issuing a tornado watch for parts of Pennsylvania and New York. The storms ended up producing multiple embedded weak tornadoes across the region. Tornadoes were not the primary threat; however, and straight line wind gusts up to 85 mph were reported in parts of Pennsylvania and New York which caused a significant amount of damage in the impacted areas. Numerous reports of downed trees and power lines were received throughout parts of the Northeastern United States before the event came to an end.

Canton–Fruitvale–Emory, Texas
This destructive EF3 wedge tornado first touched down about 25 miles to the south of Canton, Texas, at 5:41 pm CDT, before it began moving north towards town. The tornado crossed SH 19, causing only EF0 damage at this point. By around 6 pm, a Particularly Dangerous Situation tornado warning was issued for Canton, as reports of a large wedge tornado approaching town were received from storm chasers in the local area. Reaching EF1 strength, the tornado completely destroyed The Rustic Barn, a ceremony and wedding venue in this area. There were 20 people inside the structure when the tornado hit, though remarkably, no injuries occurred at that location. The tornado then intensified to EF3 strength as it approached I-20 from the south, toppling metal truss towers to the ground. The wedge tornado crossed the interstate, destroying a Dodge dealership and snapping or debarking many trees. Several motorists sought shelter by parking their cars underneath an overhang at the dealership and survived without injury despite severe damage to their vehicles and the building. However, not all motorists in this area were as fortunate, and one woman was killed as her vehicle was thrown from the interstate into an open field. Several other vehicles were swept from the interstate into a ravine as well. Some cars from the Dodge dealership were found up to half a mile away from where they originated, with their showroom license plates still attached. Several metal self-storage buildings and a restaurant were also heavily damaged in this area, along with the Yesterland Farm amusement park. EF3 damage continued to the north of I-20, and multiple homes and farm structures were destroyed along this segment of the path.

The tornado weakened to EF2 strength as it crossed County Road 1106 but was still causing significant damage as it continued northward towards the town of Fruitvale. By 6:15 pm, the tornado proceeded to strike the western part of Fruitvale, severely damaging homes, downing many trees and power lines, destroying outbuildings, tossing vehicles, and killing farm animals in this area. North of Fruitvale, the tornado maintained EF2 strength as it continued to the north and crossed into Rains County. EF2 damage continued further to the north, and the tornado crossed US 69 to the southeast of Emory. A church and multiple homes sustained major structural damage in this area. One home sustained very high-end EF2 damage and was left with only interior rooms standing. Barns and greenhouses were destroyed as well. The tornado continued to the east of Emory and then weakened to EF1 strength as it approached the Lake Fork Reservoir. The tornado weakened further to EF0 strength as it crossed the reservoir and FM 514 before dissipating. Two people were killed and 24 others were injured by this tornado, which was up to a mile wide at times.

The following day, the mayor of the city, Lou Ann Everett declared a need for assistance following the event. She also reported during this speech that "The damage was extensive in the affected area. I have just driven through some of it and it is heartbreaking and upsetting to say the least."

Flooding impacts
According to the NWS, multiple reports of flash flooding had impacted several states, in a range extending from Oklahoma to Missouri.

Late on April 28, a flood watch was issued for a large portion of the Central United States as high moisture clashing with the stationary front was expected to create life-threatening floods, potentially being caused by thunderstorm training. Rainfall totals of up to 11.05 in caused significant damage to property and crops. A large amount of farmland was rendered unusable due to the catastrophic flooding. Farmers had also made plans to plant crops, however, those plans had to be cancelled due to their farmland being flooded.

The flooding has also caused sewage and chemical waste to mix with the rainwater, causing fears of poisoning. Sandbagging efforts have been full-fledged as the Mississippi River continued to rise.

In addition, multiple water rescues were being carried out in places that had been deluged with heavy rainfall overnight, some areas picking up to 6 in in only 12 hours. In total, some locations were able to pick up almost 1 ft of rainfall during the ordeal. Rainfall rates of 1 to 2 in per hour caused flash flooding to occur in a lot of areas. Storm drains were not able to handle the large amounts of rain so a lot of these sewers ended up backing up onto the streets. Many vehicles that attempted to drive through flooded streets were swept away and/or stranded by the floods. Rivers reached moderate to major flood stages in a lot of locations which caused general street closures and severe overflow of rivers. In addition, certain levees were overwhelmed by the large amounts of rain.

Oklahoma
On April 29, in Oklahoma, the Oklahoma City Fire Department advised residents to stay home due to downed trees and power lines. In addition, multiple portions of interstates, including I-235, I-44, and I-40 had to be shut down because of downed power lines and flooding. Lightning ignited a home fire according to news outlets, while a second was reported to have possibly triggered another. As much as 39,000 were reported to have been without power by early on April 29.

Missouri
Parts of I-44 in Missouri were closed after the interstate began to flood. Route 141 was closed at I-44 well into the week of May 7–13 due to the floodwaters overtopping the low-lying intersection. This was the second occurrence of this thoroughfare's extended closure since December 2015.

Seven levees on the Missouri River were overtopped by water, while another seven levees have been breached altogether. Officials in Missouri continue to warn about potentially contaminated floodwater and advised residents to avoid the water at all costs. The governor of Missouri was forced to declare a state of emergency for all of southern Missouri after the floods began to damage property. Officials estimate that some 200 homes have been affected by the floods near St. Louis and that another 1500 homes could be at risk by the floodwaters. Due to flooding at Busch Stadium, a game between the Saint Louis Cardinals and Cincinnati Reds was postponed.

Arkansas
Officials in Arkansas estimate that close to 1 million acres of farmland have been affected in the state. The University of Arkansas stated that damage totals could be near $64.5 million US dollars. Close to 50 homes have been damaged in Randolph County in Arkansas while 76 residents had to be evacuated due to floodwaters threatening a nursing home. A levee failure in Pocahontas allowed for water to spill into a small town; threatening about 6,500 residents. A total of 108 National Guard members have been deployed in the state for relief. The governor of Arkansas also stated that close to 500 evacuations had already been carried out and that they have 25 vehicles prepared in the case that more evacuations needed to occur.

Louisiana
In Louisiana, a school bus was stranded after attempting to cross a flooded roadway. The Mississippi River reached a top five crest at 12 ft above flood stage.

Snow impacts
The same weather system produced heavy snow affected parts of Colorado, Wyoming, Kansas, and Missouri.

On April 28, residents in Denver, Colorado and other major cities began preparing for the storm. Officials were also worried that because of the time of year where most trees were in full bloom, the heavy wet snow might cause branches to break and fall down, possibly causing power outages. In Boulder, where a golf tournament was being held, officials were prepared for possible delays to the tournament. In the end, Denver picked up 5 in, with higher amounts in the mountains. At the height of the storm, up to 9,200 were reported to be without power in Pueblo.

Previously, the winter storm had dumped up to 2 ft of snow in the higher elevations of Wyoming. The state's Department of Transportation also urged residents to stay off the roadways if necessary. In addition, US 16 was shut down in the Bighorn Mountains because of the treacherous conditions.

Blizzard warnings were issued for Kansas and the adjacent areas, as heavy snow and gusty winds were predicted. After the storm subsided, about 100 evacuations and 36 rescues were reported. In the northwestern part of the state, 130 mi of I-70 was shut down due to the treacherous conditions.