More severe weather threats likely in May after unusually quiet April for tornadoes

May is already off to an active start.

The May 2 tornado outbreak comes after an extremely quiet April for severe weather.

Over the weekend, the National Oceanic and Atmospheric Administration Storm Prediction Center tweeted that April 2021 saw the fewest reported tornadoes since 2000. April also had the fourth fewest tornado watches on record.

There were 155 tornadoes in April across the U.S., many of them occurring in the central and southern plains. April 21 saw just 73 reported tornadoes, less than half of the monthly average.

Compare this to March of 2021, when there were 191 reported tornadoes across the U.S. -- more than double the average number of twisters for the month. March typically averages 80 tornadoes.

In a statement to ABC News, Matthew Elliot, warning coordination meteorologist for NOAA'S Storm Prediction Center, said, "While April is often one of the most active months for tornadoes, the occurrence of tornadoes requires ingredients to come together in a specific manner, and this did not occur very frequently during the month. One of the limiting ingredients was the lack of consistent, deep, rich, high-quality Gulf of Mexico moisture across the southeast and into the plains through much of the month."

Last April, there was a single outbreak of 140 tornadoes from Texas to Maryland. The outbreak was the deadliest since 2014. April 2020 would ultimately have over 350 reported tornadoes.

Although severe weather was notably low through April, on the evening of April 28, a round of severe weather led to large hail in parts of the Dallas/Fort Wort, San Antonio and Oklahoma City metro areas. The hailstorms, which contained hail up to the size of a softball, caused significant damage to cars and homes.

The beginning of May got off to an active start on the evening of May 2, when 23 tornadoes were reported across four different states.

May typically is a month when severe weather rapidly escalates, especially across the southern and central Plains.

An essential ingredient for tornadoes in the Great Plains is the meeting of moist warm air and cooler dry air. A look at the Climate Predictions Center temperature outlook for the middle of the month shows that this will occur in the central U.S. While the magnitude of the severe weather remains to be seen, it is looking more likely that the weather pattern will be conducive to more frequent severe weather events, as expected, as we head toward the middle of the month.

"Even though April was relatively quiet, it is hard to predict how the rest of the season will unfold," Elliot said. "May is often the peak of the tornado season, so it is important to be vigilant when thunderstorms are in the forecast and to be prepared to take action should threatening weather approach your area."

ABC News' Daniel Peck contributed to this report.