USA - Hurricane Lee, Climatology, Data Truncation and the News
Noon, September 16, 2023 – An Associated Press headline this morning trumpeted “Climate change could bring more monster storms like Hurricane Lee to New England.” I immediately went to the National Hurricane Center (NHC) website to see the most current conditions. Lee had been downgraded to a post-tropical cyclone with 75 mph winds.
But it still covers a lot of territory. As of noon, Lee is producing 1-2 foot storm surge and tropical-storm-force winds in portions of Maine. NHC gave the northeastern tip of Maine a 5-15% chance of flash flooding. They predict 1-4 inches of rain over portions of the state that receive rain, though the extreme eastern tip may get up to 6 inches.
Does Climate Data Support AP Claim?
Next, I went to NHC’s Climatology page to see how unusual hurricanes are in New England. Because of the colder waters, they’re certainly not as frequent as hurricanes in the Gulf of Mexico. But they’re also not unusual as you can clearly see from the image below. It shows hurricane tracks going back to 1851.
Next, I looked at the points of origin for Atlantic storms in the 10-day period each season from Sept. 11 – 20.
In fact, during September, there’s at least a 70% annual chance that a hurricane will affect this region (see below).
Data goes from 1944 to 2020, but is normalized for 100 years. 1944 was the year NOAA started tracking hurricanes with aircraft.
The AP article related higher than normal sea surface temperatures to BOTH climate change and the risk of being affected by a hurricane in New England. It’s true that temperatures ARE above average off the New England coast this year. But it’s also true that temperatures cycle above and below an “average.” You can’t assume that sea surface temperatures ALWAYS increase.
This 28-second animation of sea surface temperature (SST) anomalies from 2002-2011 shows how temperatures vary monthly and annually around the world as well as off the coast of New England.