By Chelsea Ingram

PHILADELPHIA (CBS) — Severe weather across our area has been the rule rather than the exception as of late. That’s also been the case across the country.

According to the preliminary tornado report statistics from the Storm Prediction Center, at least 1,008 tornadoes have touched down across the nation, with more than half occurring during the month of May.

This year, Pennsylvania has already seen more than 20 tornadoes. On average, the commonwealth typically sees about 17 tornadoes per year.

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So what’s been the cause of this extreme weather and uptick in tornado touchdowns? The simple answer is the atmospheric pattern across the United States, specifically for our region, high pressure over the southeast has been driving warm, moist air into the Delaware Valley.

We do not have any evidence when it comes to changes in intensity with tornadoes. However, variability has increased.

On the graph below, you can follow the blue line to see that the number of days with tornadoes has gone down.

Credit: CBS3

However, the red line shows an increase in what can be considered as big days. In other words, days with at least 25 tornadoes or more across the country, have gone up.

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Connecting all of this with climate change is hard to do. According to The National Weather Service Storms Laboratory, there’s likely some type of connection, but a direct association is missing.

So over time, with more research and more consistency within the database, we will hopefull have a better understanding on a possible relationship between tornadoes and our changing climate.