A Very Active 2023 Tornado Season Across the Northeast

September 7, 2023 // Article by: Steven Weinstein

It sure has been an active past few months and year so far with regards to severe weather, flash flooding, and tornadoes across the Northeast. Even recently, a bout of severe weather during the morning hours of August 18th spawned 5 tornadoes across parts of Connecticut, Rhode Island, and Southeastern Massachusetts. One of the twisters in Rhode Island was significant and given an EF-2 rating with estimated winds of up to 115 mph! However, these seemingly "rare" and "significant" tornadoes have actually been pretty common across parts of the Northeast in 2023. Certainly it is a bit abstract to deem the Northeastern U.S. as a new tornado alley, as the Great Plains and Southeastern U.S. states (i.e., Dixie Alley) are the traditional regions that come to mind when one thinks of tornado hotspots. However, there is no denying how anomalously active this year has been. This had us thinking: Just how abnormal has 2023 been with regards to severe weather and tornadoes across the East Coast? Are tornadoes (including significant ones) occurring at a higher frequency across the Northeastern U.S. than ever before? And, are tornadoes getting stronger over time?

When talking about the Northeast, the rough coverage area used for this study included areas of Southeastern Virginia, spanned all the way up and along the I-95 corridor (including parts of Eastern Pennsylvania, Long Island, and the Lower Hudson Valley), and culminated in scope across Southern New Hampshire. Let's take a deeper dive into some of the counts and statistics surrounding tornadoes across the East Coast not only so far this year, but overall since 2010, with a strong emphasis on the state that has seemingly bared the brunt of this activity in 2023, New Jersey.

Tweet from NWS Boston giving the specific details of the 5 tornadoes that impacted New England on August 18th, 2023.

Diving into some of the statistics of 2023, so far there have been 58 severe days (which includes any day with at least one wind report of 58+ mph, a hail report of 1" or greater in diameter, and / or a tornado). For reference, the average number of days from 2010 - 2022 is almost 63 severe days, with a low of 50 days in 2015 and a high of 77 days in 2011. More specifically, we have seen 15 tornado days (i.e., any day with one or more tornadoes) so far in 2023 corresponding to 43 total tornado reports across the Northeast. How does this stack up to the average? Well, as you can see the average number of tornado days across the Northeast from 2010 - 2022 is 11.5, with the maximum number of days being 18 in 2011 and 2018, and the minimum being 6 in 2016 (see graph below). Meanwhile, the average number of tornado reports during this timeframe is 26 per year, with the maximum number of reports being 60 in 2021 and the minimum being 9 in 2015. While there is clearly a big spread in days and reports, the counts show just how active this year has been so far with the 15 days ranking at the 75th percentile (meaning 75% of all data from 2010 - 2022 falls below this value) and the 43 reports ranking near the 88th percentile (meaning 88% of all the data from 2010 - 2022 falls below this value). 

Courtesy of WeatherWorks LLC.

From a more regionalized standpoint, while the Mid-Atlantic and New England have been holding their own with regards to tornado activity this year, we'll see that it is Eastern Pennsylvania (particularly east of the I-81 corridor) and all of New Jersey that have been the relative hotspots for tornadoes. These states have made up 9 out of the 15 days that the entire Northeast has seen, including 6 of the first 7 tornado days this year. New Jersey in particular is a state that has garnered a lot of media attention this year regarding tornado activity, especially given the number of significant tornadoes (i.e., those with an EF-2 rating or higher on the Fujita Scale and estimated winds of at least 111 mph) that the state has seen this year. Just how unusual has this very active tornado season been across NJ? Well, the state has already seen 13 total tornado reports, which is well above the average of ~2 reports per year from 2000 - 2022 (see graph below). Overall, the total of 13 reports for this year ranks in the 96th percentile for all the data from 2000 - 2022, tying the other all-time high of 13 set in 2021! The other thing quite noticeable from the graphic below is that even though highs and lows in activity are rather typical from year to year throughout the time period with plenty of years finishing with 0 tornado reports, the more recent years and linear trend suggests that the number of tornadoes could actually be increasing with time. 

Courtesy of WeatherWorks LLC and the Storm Prediction Center (SPC).

Expanding more on the significant (EF-2+ rated) tornadoes discussion, these such events are traditionally considered to be quite rare across the Northeast. However, as we will now investigate, it has been a quite abnormal year from that perspective as well. 7 significant tornadoes have touched down across the Northeast so far this year, with 4 of those occurring in Central and Southern New Jersey! 5 of those were rated EF-2, with 1 across Delaware and another in Southeastern Virginia being given an EF-3 rating. Amazingly, 6 out of the 7 occurred during the months of February to April which is actually well outside of the peak tornado season climatologically. How do the 7 such tornadoes compare to the average number that we see per year across the Northeast? Since 2010 and including those we have seen in 2023 so far, there have been 31 total significant tornadoes. This corresponds to an average of just under 2 per year from 2010 - 2022. Therefore, this year has certainly been well above average with the 7 significant tornadoes currently tied for first with the 2021 season, which was another anomalously active year. What about the trend over time? As we can see in the graph below there may be an upward linear trend in significant tornadoes in recent years. Now whether or not this is truly a trend remains to be seen with last year actually recording 0 significant tornadoes. However, one thing that seems to be evident in recent years is that the highs are getting more extreme with regards to all aspects of tornado climatology. 

Courtesy of WeatherWorks LLC.

Clearly, we have seen a lot of tornadoes up to this point in 2023 and are already well above average. Hopefully these statistics give you some insight into how unorthodox this year has truly been for the entire Northeast as well as New Jersey in particular. While there are overall indications of upward trends in tornado climatology and severity across the Northeast as evidenced through this data, it is nearly impossible to say that this is the new norm just yet or to link these recent upticks to climate change. Indeed, only time will tell the story, but it is important to understand that an overall increase in severe weather frequency and intensity is surely a theory that supports the principle of our changing climate. Additionally, although the tornado activity this year isn't quite to unprecedented levels, it is important to understand that the 2023 tornado season is far from finished. Yes, tornado activity has already peaked for the year as we are now entering into the fall months. However, you can see that the last 4 months of the year still hold their own with regards to tornado activity as we still average almost 3 more tornado days per year across the Northeast from September to December. This corresponds to an average of nearly 8 more tornado reports. Lastly, on average we see around 9 more severe days from September to December. Therefore, the tornado and severe season is far from over and it is important that we remain alert and weather aware even as we head through the next several months.