Monday, January 3, 2011

2010 Annual Climate Summary and MWN Forecast Accuracy

2010 is in the books and history will show that it was a very warm and very dry year in Memphis, TN. While there certainly were exceptions (for instance, the 7" of snow received and the historic flooding of May 1), overall the extreme heat and drought of late summer and fall resulted in the year ending up above normal temperature-wise and below normal for precipitation. A full summary appears below.

(Note that, for variety, I will interchange the terms "normal" and "average" throughout this summary. However, my preferred term is average, as normal can connote that anything above or below average is "not normal." In fact, it's highly unusual if the year turns out exactly "normal." But I digress...)

Memphis International Airport, Memphis, TN

The 2010 average temperature was 63.6 degrees, which was 1.4 degrees above normal and 1.2 degrees warmer than 2009. The average high temperature was 73.2 degrees (1.1 degrees above average) and the average low was 53.9 (1.4 degrees above average). The freezing mark was reached 71 times during the year, 15 more than a normal year, while the high temperature failed to climb above freezing on 9 occasions. The high temperature reached 90 degrees or greater on 108 days, or 45 days more than a normal year. The lowest temperature for the 2010 was 9 degrees set on January 8th and the highest temperature was 104 set on August 4th. There were 3211 heating degree days (170 above the long-term average).

Precipitation for the year totaled 47.90", or 6.75" below the normal of 54.65" and more than 13" below 2009's total of 61.26". This was evident in the fact that the region spent much of the last third of the year in drought conditions (moderate to extreme). There were 89 days with measurable rainfall, compared to a normal of 107 days, and 17 days in which an inch or more fell, compared to a normal of 16. A thunderstorm was reported on 53 days, heavy rain on 37 days, The maximum 24-hour total was 3.51" on April 30-May 1.

There was 7.1" of snow that fell in 2010, or 1.4" above the long-term average and 3.0" more than in 2009. Snowfall was recorded on 16 days and two days had more than an inch accumulation. Freezing rain was also recorded on two days, sleet on four days, and hail on two days. The greatest 7am snow depth in 2010 was 3.0" recorded on February 8th.

The peak wind gust at the airport for the year was 56 mph (from the west) on March 11th, while the average wind speed for the year was 7.4 mph and the dominant wind direction was southerly (194 degrees). Dense fog (visibility equal to or less than 1/4 of a mile) was reported on six days. The average relative humidity was 62%. Click here for a full statistical recap for Memphis International Airport.

Bartlett, TN

The average temperature for 2010 at the Davis Vantage Pro2 weather station in north Bartlett (WXLIVE!) was 62.0 degrees (0.7 degrees warmer than 2009) with a maximum of 103.1 on August 4th and a minimum of 7.6 degrees on January 10th. There were 3712 heating degree days and 2648 cooling degree days in 2010.

Precipitation for the year ended below normal with a total of 52.29", less than the 56.00" recorded in 2009. The total was over 4" more than Memphis International Airport received, due mainly to the amount of rain received on May 1, when Bartlett recorded 10.51" to the airport's 3.51". The peak wind gust recorded in Bartlett was 40 mph on April 24th and the dominant wind direction for the year was south-southwest. Average relative humidity was 67%. Click here for a monthly recap on

MWN Forecast Accuracy for 2010

For the year, the average temperature error in all temperature forecasts was 2.05 degrees, the best of all compared computer models, by at least 8.7%. In all, 68.3% of MWN temperature forecasts for 2010 were within 2 degrees of the actual temperature. It was also the most accurate year in the 13 years that MWN has kept records! MWN's forecasts extend out five periods (or 2.5 days) and a total of 535 forecasts were issued in 2010. For dewpoint accuracy, the MWN forecast was also the best of the data sources at 2.52 degrees average error and was within 2 degrees of the actual dewpoint over 60% of the time. Detailed accuracy statistics for the year can be found here.

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