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Discovering regional differences (a.k.a. my first tropical storm)

One thing I was excited about upon moving out of Michigan, the state where I've lived for 99.2% of my life¹, is discovering the little regional differences that gives each place its true character. It's the things you wouldn't necessarily pick up as a tourist passing through for a few days that are more fun. So far there's been the unsurprising (the large number of seafood shacks), and the more surprising (finding that wearing polos with the collar popped isn't done by a large segment of the population, not just preppy frat boys; finding wearing dock shoes without socks is cool, etc.).

One of the more obvious differences is the possibility of tropical storms/hurricanes. However, Connecticut is pretty far up the coast, and upon doing a little research, I found only 9 storms have ever reached Connecticut as hurricanes since 1856; only one within the last 25 years. And while tropical storms are a little more likely than hurricanes, the last time one affect CT was when Floyd came through in 1999, nine years ago. The image below shows all hurricanes (red), tropical storms (yellow) and tropical depressions (green) to affect New London county in the last 50 years.
Hurricanes, Tropical Storms, & Tropical Depressions near New London County, CT since 1958

Tonight Tropical Storm Hanna will blow through CT, with the center of circulation coming quite close to my location (see map from Google Earth below). I'm finding myself strangely excited to get a chance to experience a tropical storm- something I feel somewhat guilty for, since people are suffering through some property damage, power outages, and probable injuries as a result of Hanna already. A tropical storm is just so different from any type of weather we'd get in the Mid-West, that I find myself looking forward to the new experience.
55pm

I'm tempted to throw on a rain slicker and some goggles and head down to the beach Jim Cantore-style as Hanna blows through (I won't really).

Images
Historic Hurricane Tracks from NOAA Coastal Services Center
Hanna's Projected Path from Google Earth

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¹ That is: 353 of my 356 months of existence.

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Tropical Storm and Hurricane Frequency

September, 2005: The school year has just begun. The country is still reeling from Hurricane Katrina.

Instead of beginning the year covering plate tectonics (my original plan), I decide to start with hurricanes. As we learn more about Katrina and hurricanes in general, the question keeps coming up in class (and in the media): "Are we getting more hurricanes because of global warming?"

I struggled with how to answer that question. Reports from scientists were mixed. The most reliable sources (IMHO) never made a direct connection between global warming and the trend of more active hurricane seasons. They'd only go as far as something similar to, "hurricanes get their power from warm oceans. In theory, if oceans get warmer, it would make sense we'd see more hurricanes."

That didn't cut it for my students. 15-year olds don't have great appreciation for the subtleties and complexities of meteorological research. They wanted answers.

I stumbled across a website containing records of every reported hurricane and tropical storm from 1851 on. Aha! Oho! Forget the experts, let's track the trends ourselves!

I split the class into groups. Each group took a decade and recorded the number of hurricanes and tropical storms each year in their decade. Back in the pre-Google Docs era, we were forced to spend 30 minutes or so sharing data and entering into their individual spreadsheets. Today, just create a Google Doc spreadsheet (like this one!) and have each group enter their data (an example of collaborative online documents saving a huge amount of time & boredom).

Then comes the graphing! . I've found Google Docs graphs aren't too great at this now (they might get there soon), but exporting the data to Excel is easy enough.

We added moving average trendlines to see the trends. You can play with how long the moving average should be. We decided that 5-10 years seemed to give a good picture of the trends. The graphs below have trendlines with a moving average of 10 years.

The graphs:

Hurricanes by Year

Tropical Storms + Hurricanes per Year

Fun fact: The first time I saw these graphs was in class (and my students knew that). I didn't know what trends would emerge. My students and I were learning together, and they seemed to like participating in the discovery of something that wasn't pre-determined.

Good discussions that fit well with this activity

  • How valid are the counts and intensities for tropical storms before reliable weather satellites and radar were in use? Most storm reports back in the day simply came from ships at sea. How would the data be affected if several storms went unreported each year?
  • Does this information prove causality? (It doesn't) As much as it looks like it, there's no way we can say with any certainty that global warming has caused the uptick in tropical storms recently.
  • Would coastal development have occurred at the same rate the last 50 years if hurricanes were as frequent as they have been the last few years? Lots of good discussion can be had as to the wisdom of living on the coast, students seem to have strong opinions one way (you'd be stupid to do this) or another (It's way worth the risk to live on the ocean).

Whew. I'm feeling a bit like this guy. What can I say? I'm a fan. Comment it up!

Image credit: NOAA via GISUser.com on Flickr

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