Monday, May 11, 2009

Exploring Tennessee's Climate

Well I am going to attempt our blog series where we explore each CoCoRaHS state's climate and hopefully we all will learn something new.

I have a variety of sources for my information, and may find new ones as we go along.

I am going to start the series today with the state of Tennessee.

The climate of Tennessee is quite interesting simply due to the shape of the state, stretching several hundred miles from the Gulf Coastal Plain along the Mississippi River, all the way to the peaks of the Blue Ridge Mountains along the North Carolina border.

Overall, it could be described as mild and wet.

Most of Tennessee is classified as having a humid sub-tropical climate, but the highest terrain along the eastern border is considered to be a maritime temperate climate.

Although maritime usually describes climates that are near an ocean, it can also be used to describe places inland that have climates similar to tropical or sub-tropical areas in terms of annual moisture moisture, but the temperatures are too cool to be truly classified as tropical or sub-tropical.

In the United States, there are only a handful of inland locations with a maritime temperature climate, and they are mostly along the spine of the Appalachian Mountain chain from Pennsylvania to east Tennessee.

Europe has the highest number of inland locations classified in the maritime temperatate climate zone. In fact, the majority of the continent is classified in the maritime temperatate climate zone.

Tennessee receives a copious amount of moisture annually. Winds from the south transport most of the state's annual aveage of 50 inches of moisture from the Gulf of Mexico.

Here is the average annual precipitation for a few major cities.

  • Memphis (west Tennessee on the Arkansas and Mississippi border) -- 54.65 inches
  • Knoxville (east Tennessee near the North Carolina border) -- 48.22 inches
  • Chattanooga (southeast Tennessee near the Georgia border) -- 54.52 inches
  • Nashville ( middle Tennessee near the Kentucky border) -- 48.11 inches

    One thing I noticed right off the bat by just taking a quick look at the data from the 4 cities above is that Memphis and Chattanooga are almost the same and so are Nashville and Knoxville.

    Now look at the map above and find Memphis and Chattanooga. They are nearly on the same line of latitude and both on the southern border of the state.

    And by latitude, I mean you could nearly draw a straight east-west line between the two locations.

    Nashville and Knoxville are also nearly on the same line of latitude and both are much further north, closer to the top of the state.

    Of course just using those 4 data points is not enough to make a generalization about the whole state of Tennessee, but seeing as how they are very well spread out and represent most of Tennessee, I am inclined to say that the average annual precipitation drops off as you head north.

    Which would make sense since you are moving further away from the moisture source for Tennessee, which is the Gulf of Mexico.

    In my next blog entry, we will explore the precipitation patterns of Tennessee a little more -- and talk about an interesting flip flop of rainy vs. dry seasons as you travel from Memphis to Knoxville along Interstate 40. (a VERY LONG drive by the way -- but also VERY SCENIC)

    1. Chris,

      I just got back from Pennsylvania. I was there for a week, and forgot how 70 degrees with 100 percent humidity is quite warm. There was lots of rain and at times it came in torrents. Friday was the best day with the temp of 79 degrees. I came back to EWA and it felt like fall. One interesting bit of info was that while I was gone, a tornado hit about 45 miles from our place. I didn't even know we got them here.

    2. Hi Chris:

      Thanks for this informative and interesting article about 'my states' weather!! As a blogger located in Middle TN, I appreciate you writing about us.

      Enjoying CoCoRaHS for nearly two years here. Will link to your article..

      Cookeville, TN

    3. Because of this entry I was able to intelligently maintain a conversation about TN last evening on the golf course! Thanks, Chris. :)