Earth 365: Is climate change causing more severe weather in Pittsburgh?
PITTSBURGH (KDKA) - One of the biggest areas of concern when it comes to climate change is the risk of more severe weather.
In just the past year, we've seen tornadoes in late October, record-setting snowfalls in mid-March and more frequent flash flooding. But are we actually seeing increasing extreme weather here in southwestern Pennsylvania or does it just seem that way?
Fred McMullen, a warning coordination meteorologist with the National Weather Service in Pittsburgh, says it starts with knowing what the definition of extreme weather is.
"It's a tornado emergency like last December in Mayfield, Kentucky or a derecho that went through in 2012 in Ohio and West Virginia. It's back-to-back tropical systems that happened in 2004 in western Pennsylvania. You could also talk about snowmageddon or the superstorm in 1993," McMullen said.
First, let's talk about the most recent extreme weather we've seen. In March, we set two single-day snowfall records and the month came in as the snowiest March since 1993. Yet, the overall temperatures last month averaged 3 degrees warmer than normal.
"So this is where you can lose things in statistics, right? You have these days in the mid-60s and pop into the 70s and a handful of days throughout the month and those kind of weigh out the cold days. You really have to dig into the numbers to see the impact on climate. Most of our snow happened on two days," said McMullen.
As for flooding, McMullen said, "Going back for Pittsburgh specifically, in the last six years we've had three precipitation events that exceeded 3 inches of rain in one hour. Now, for the previous 40 years, we only had three of those."
Stronger and more frequent tropical systems can and often do impact our region. Late last summer, Hurricane Ida made landfall in New Orleans but caused greater damage from Philadelphia to New York. Along the way, the storm's remnants dropped 6 to 7 inches of rain across Pennsylvania during the first few days of September.
"When we see tropical systems in September, we can never assume they will make landfall in the south, they will weaken and they won't cause any impacts to us. When really they have significant impacts to us and historical references like Hurricane Ivan, Frances and Agnes," McMullen said.
Finally, tornadoes. We've certainly had our fair share over the years. But last October, we saw 21 documented tornadoes in one day across western Pennsylvania, eastern Ohio and northern West Virginia. By comparison, there were only 11 October tornadoes in the same area from 1950 to 2020. That's 11 tornadoes in 70 years versus 21 in one day.
"We had a busy October of 2021. In January 2019 we did a survey in Mercer County. We did a tornado survey, the first one ever recorded in February, in Uniontown in 2018. So we've been having these tornadoes outside our peak window, which is usually May through the early part of July," said McMullen.
The takeaway? It does appear western Pennsylvania's severe weather patterns are changing, although slightly.
And it means we can't let our guard down for severe weather at any time during the year just because we're in a month when we normally don't see tornadoes, record-breaking snowfall or tropical storm flooding.
On Tuesday: A look at how our changing climate is affecting our health, specifically when it comes to allergies.