|A chart of the 2017 current United States tornado count (adjusted for inflation)|
|Timespan||January 5 – Currently ongoing|
|Maximum rated tornado|| EF5 tornado|
Mount Dora, Florida on May 23
This page documents the tornadoes and tornado outbreaks of 2017, primarily (but not entirely) in the United States. Most tornadoes form in the U.S., although some events may take place internationally, particularly in parts of neighboring southern Canada during the Northern Hemisphere's summer season. Some tornadoes also take place in Europe, e. g. in the United Kingdom or in Germany. Tornadic events are often accompanied with other forms of severe weather, including strong thunderstorms, strong winds, and hail.
There have been 1,095 reports of tornadoes in the United States in 2017 so far, of which at least 931 have been confirmed. A total of 489 tornado-related deaths have occurred worldwide as of June 30: all in the United States (10 fatalities occurred due to other severe weather conditions; 5 during winter storm conditions during a winter storm in early January, and another 5 during a widespread outbreak in mid-April). 2017 has become the most active first quarter since records began in 1950, beating out the previous record holder of 2008 for the most tornadoes from January to March; and one of the fastest starting years in recorded history.
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- Other tornado outbreaks have been confirmed in each month, but statistics for these tornadoes have yet to be officially released. There are several outbreaks currently under evaluation, all of which are currently in the process of being documented and released.
Extreme levels of tornadic activity took place in January. There were 227 preliminary reports of tornadoes in the United States in January, of which at least 193 were confirmed. This is over 6 times the monthly average of 35, and the most active January since 1999. The extreme activity during the month was attributed to an unusually spring-like setup in the latter half of the month, with a warm, moist air mass from the Gulf of Mexico flowing northward into an area with strong upper-level westerlies. The synoptic set up of these factors was typical of March or April rather than mid-winter.
- Main article: Early January 2017 Gulf Coast storm complex
On the evening of January 5, a series of destructive tornadoes impacted areas in Mississippi and Alabama, resulting in multiple fatalities and major damage across densely populated areas. During that evening, a large EF4 wedge tornado touched down in extreme western Lee County with major damage occurring in Tupelo. The Tupelo tornado completely destroyed numerous homes and vehicles along its path and killed 19 people. The parent storm system went on to produce several other tornadoes across the Southern United States into the next two days. Overall, the storm system produced 31 tornadoes, along with significant snowfall and flooding.
- Main article: Tornado outbreak of January 16–18, 2017
A powerful spring-like storm system brought an unusually large winter tornado outbreak to Arkansas and surrounding states during the afternoon and evening hours on January 16, 2017, and severe weather would persist over the same area for the next two days. This resulted in the largest tornado outbreak on record for January, as well as one of the largest overall in a 24-hour period, which affected the southern half of the Mississippi River Valley and surrounding areas. Within this time frame, 135 tornadoes touched down, setting the record for the most tornadoes in a single outbreak for January. Eleven people were killed in this outbreak, and over 132 million dollars in damages occurred.
- Main article: Tornado outbreak of January 29–30, 2017
Just less than two weeks after the largest tornado outbreak on record for January, a much smaller tornado outbreak developed around the areas devastated by the previous storms. Much less damages occurred, but several significant tornadoes touched down over the course of this outbreak, resulting in major damage and several fatalities.
Similar to the previous month, above average activity occurred in February, albeit more spread out. There were 151 preliminary reports of tornadoes in the United States in February, of which at least 72 were confirmed. This is over twice the national average of 29 tornadoes.
- Main article: February 9, 2017 tornado outbreak
A localized outbreak of 19 tornadoes affected the southern portions of the states lining the Gulf Coast, causing widespread damage in the region.
- Main article: 2017 Mid-Atlantic tornado outbreak
The February 25, 2017 tornado outbreak was a violent outbreak of 53 tornadoes which took place in the Mid-Atlantic region of the United States, killing 22 people and injuring hundreds more. At least one tornado which hit the Jacobs Fork area in North Carolina has been rated EF4.
March continued the above average trend of the previous months. There have been 138 preliminary reports of tornadoes in the United States during March, of which at least 101 tornadoes have been confirmed.
- Main article: Tornado outbreak of March 15, 2017
An event hastened by the passage of Winter Storm Stella occurred in Tennessee on March 15, with the worst damage occurring in Nashville. On that day, twelve tornadoes swept through Middle Tennessee—two of them touching down in Nashville city limits, causing significant damage to the downtown and East Nashville areas. Nashville became the first major city in nearly 6 years to have an EF2 or larger tornado make a direct hit in the downtown area.
- Main article: March 21–23, 2017 tornado outbreak
The March 21-23 Central US tornado outbreak produced 64 tornadoes across the region including a very long tracked EF4 tornado that traveled for 90 miles.
There were 190 tornadoes reported in the United States in April, of which at least 165 have been confirmed. Similar to the other months, April reached above average activity, albeit marginally. The monthly average is 155 tornado reports.
- Main article: Tornado outbreak of April 6–8, 2017
During the afternoon of April 6, a significant tornado outbreak started setting up. A PDS (Particularly Dangerous Situation) tornado watch was issued for much of eastern Colorado. Supercells explosively developed over central Colorado. Storm chasers in the region reported several funnel clouds and two touchdowns, neither of which resulted in damage. Several tornadoes were confirmed through storm chaser video and local emergency management services.
During the late-night hours into the morning of April 7, tornadic activity lessened. However, by the late morning hours, supercell thunderstorms developed again over parts of Arkansas, and tornadoes began to touch down again. Over 20 tornado sightings were reported and at least eight people were killed.
- Main article: Tornado outbreak of April 17, 2017
A small, yet severe series of tornadoes touched down within a larger outbreak that affected southern portions of the Midwestern United States on April 17. Tornadoes developed in the states of Illinois, Indiana, and Ohio; with eastern Illinois being hardest hit after an EF4 tornado ripped through densely populated sections of Danville, Illinois.
There were 165 reports of tornadoes in the United States in May, of which at least 127 were confirmed.
An multi-day severe weather event produced widespread damage in the Great Plains, including a confirmed 74 tornadoes.
- Main article: 2017 Central Florida tornado outbreak
A significant and unusual tornado outbreak developed across central Florida in the afternoon of May 23, 2017. In the early hours that day, the Storm Prediction Center issued a slight risk of severe thunderstorms for May 23 over central Florida. Although a highly unstable environment was in place through the morning, it was initially expected that little more than quick bursts of convection and resulting brief thunderstorms would occur due to little wind shear near the dry line. However, the influence of a passing gravity wave released by a dissipating storm system from the previous evening caused the highly unstable air to rush upward when it intersected a stalled cold front and sustain what quickly became a supercell along the surface boundary. This storm drifted unexpectedly to the southwest, as did many of the tornadoes that day. That afternoon, 32 tornadoes were reported across south and central Florida; including a large, violent tornado that touched down in the extreme southern city limits of Eustis, Florida and went on to rapidly intensify before impacting the northern half of the town of Mount Dora, inflicting some of the most extreme tornado damage ever photographed to the city's residential areas. The American Red Cross confirmed 245 fatalities from this tornado. After being initially assigned a preliminary high-end EF4 rating, it was increased, and the tornado was given a final rating of EF5. This tornado became the first EF5 tornado in over four years; and was the first ever recorded in Florida.
321 tornadoes were reported in the United States in June, of which at least 273 were been confirmed.
- Main article: Tornado outbreak of June 3–4, 2017
Following a devastating tornado outbreak in Florida that concluded the significant tornado outbreaks for May, more severe weather developed across the Midwest on June 3.
- Main article: Mid-June 2017 tornado outbreak
56 tornadoes have been reported in the United States in July, of which at least 41 have been confirmed.