2020 Had the Fewest May Tornadoes in the U.S. in 50 Years

The number of tornadoes that touched down on United States soil in May 2020 was the lowest in at least 50 years, a sharp contrast to one of the busiest Aprils for twisters on record.

May is typically the most tornadic month in the U.S., averaging 272 tornadoes each year between 1999 and 2018. But only 59 tornadoes were confirmed throughout the month, according to George Delanjian, a meteorologist at Southwest Airlines.

The last time May had fewer than 100 tornadoes was in 1970, when 88 touched down in the U.S., tweeted Evan Bentley, a severe weather meteorologist at NOAA's Storm Prediction Center (SPC). The least-tornadic May was back in 1952, when only 34 twisters were confirmed during the month, according to data from the SPC.

Additionally, the SPC did not issue any moderate (level 4) or high (level 5) risks of severe weather in May 2020, a first in records dating to 2002, noted Patrick Marsh, Branch Chief of the SPC.

It should be noted that the SPC lists 112 preliminary tornadoes in its database for May, but that includes all reports from every National Weather Service office, some of which may be from the same tornado, therefore counting it more than once.

The actual number of tornadoes won't be known until a later time, but it's likely closer to Delanjian's estimate of 59.

Parts of that corridor were relatively tornado-free this past May, most notably much of Nebraska, Kansas and Oklahoma.

This can also be seen on the map below, showing the number of tornado watches issued by the SPC since the beginning of the year. Note the lack of tornado watches over Nebraska, Kansas and western Oklahoma, in the heart of Tornado Alley.

As of May 27, only 21 tornado warnings had been issued in Kansas this year, the NWS office in Wichita tweeted. That's the third-fewest number of tornado warnings to date in the state in records dating to 1990. On average, January through May averages about 80 tornado warnings in Kansas.

This quiet May for tornadoes was largely due to a pair of unfavorable large-scale weather patterns that persisted for most of the month.

Meteorologist Jonathan Belles explains these patterns in great detail here.

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