Tuesday, May 12, 2009

More About Tennessee Climate

Yesterday we established that Tennessee receives a lot of moisture annually.

Today I want to talk more about their climate -- specifically, precipitation.

Here are the top three wettest months for the main 4 anchor cities.

  • Memphis -- April (5.79"), November (5.76"), December (5.68")
  • Nashville -- May (5.07"), March (4.87"), December (4.54")
  • Chattanooga -- March (6.19"), January (5.40"), November (4.88")
  • Knoxville -- March -- (5.17"), July (4.71"), May (4.68")

    And the top three driest...

  • Memphis -- August (3.00"), September (3.31"), October (3.31")
  • Nashville -- October (2.87"), August (3.28"), September (3.59")
  • Chattanooga -- October (3.26"), August (3.59"), June (3.99")
  • Knoxville -- October -- (2.65"), August (2.89"), September (3.04")

    So we can tell a few things about Tennessee from the wettest and driest months at the four stations above.

  • Late summer and early fall appear to be the driest months to be in Tennessee on average
  • It is hard to come up with a clear pattern for the wettest time of the year statewide other than it is wet in spring, and at most stations, also in late fall (perhaps this has to do with the second peak of severe weather season the south usually experiences in late fall)


    Tennessee averages about 50 thunderstorm days each year. Some of which can turn quite severe.

    Tornadoes are possible statewide, but west Tennessee is slightly more vulnerable. Possibly just due to location being closer to the tornado alley of the United States.

    On average, there are about 15 tornadoes per year that touch down in the state of Tennessee.

    A study out of Northern Illinois University concluded that Tennessee has the highest number of nocturnal tornadoes of any state in the United States, with 45.8% of all reported tornadoes between 1950-2005 happening overnight.

    Arkansas was second with 42.5% and Kentucky was third with 41.5%.

    Now my mind says hmmmm....why?

    The first thing that popped into my brain was simply geography and the time line that thunderstorm development usually follows.

    A common set up for severe thunderstorms is a dry line that initiates storms in the mid to late afternoon across west Texas and Oklahoma and then moves east.

    By the time it reaches Arkansas and west Tennessee it is usually night.

    I recall as a kid growing up in Arkansas watching the storms on most nights enter western Arkansas around sunset and be to us in the Little Rock area between 9 pm and midnight.

    Another study says that Tennessee doesn't have the highest number of tornado fatalities in the United States, but that it does have the highest number of tornadoes that produce fatalities.

    Which would go right along with the highest number of overnight tornadoes since most people are sleeping and don't have measures in place to monitor the changing weather conditions outside.


    Tennessee is prone to remnants from tropical systems.

    Due to the size and long shape of the state, it is possible that a tropical remnant from land-falling hurricanes and tropical storms will pass either over or close enough that some impact will be felt.

    The biggest threat is simply heavy rain, but some wind and even a few tornadoes are possible when tropical systems pass by.

    In 2005, west Tennessee had 3 tropical remains pass over the region.


    Winter storms don't hit often in Tennessee, but when they do, it can be a nightmare. This is partly due to lack of equipment to handle wintry weather, and also to a population that isn't accustomed to traveling on snow or ice.

    Ice storms can be a problem in Tennessee. They can do significant damage to trees and power lines, and trap people at home for days.

    Fog is also a persistent problem in portions of Tennessee, especially in the eastern part of the state.

    You might recall back in 1990 there has a horrible traffic accident on Interstate 75 over the Hiwassee River 40 miles northeast of Chattanooga.

    It involved over 70 vehicles and unfortunately resulted in over a dozen deaths and several dozen injuries.

    Here is a link to an article about the fog-related traffic accident.

    Tomorrow we will talk a little about temperatures in Tennessee and find out where the warmest annual temperatures can be found.
  • 1 comment:

    1. Thanks for all the research you're putting into these posts Chris, I'm eating this stuff up!

      Can't wait till you get to Missouri.