December 2012 Climate Data and Forecast Accuracy

Temperatures once again averaged well above normal, while precipitation was below normal, with the year ending in the top 10 driest on record.  Drought conditions continued to abate, even though rainfall was below normal. Most of the Memphis metro is now classified as being "abnormally dry," which northern Shelby and Tipton Counties are still in a moderate drought.  The month also saw the first snowfall of 2012-2013 winter with about an inch in most areas of the metro (slightly more north and less south) beginning around midnight Christmas night and lasting into the morning hours of the 26th.

In addition, there was one severe weather event, on December 9th, which produced hail reports in the metro and strong wind gusts.  Year-end statistics will be reported in a separate blog post, but the average Memphis temperature for 2012 set a record for the warmest on record, averaging 66.0 degrees, 0.4 degrees warmer than the previous record high set in 2007.

Memphis International Airport, Memphis, TN

The average temperature for the month of December was 49.8 degrees, or 6.2 degrees above normal, which ranks as the 8th warmest December on record. The average high temperature was 58.0 degrees and the average low was 41.5. The coolest temperature of the month was 21 degrees on the 30th, while the highest temperature was 75 degrees on the 3rd, which also tied a record high for the date. There were 9 days on which the low temperature fell to freezing or below.

Precipitation for the month totaled 3.73", which was 2.01" below average. There were 17 calendar days with measurable rainfall, but only 3 saw totals of 0.50" or more (maximum 0.92" on the 9th-10th). Snowfall from the December 26th winter storm produced 0.9".  The peak wind gust was 47 mph from the west on the 20th with an average wind speed for the month of 8.5 mph. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN

The average December temperature at Cirrus Weather Solutions was 48.2 degrees (0.1 degrees warmer than November) with a maximum of 75.1 degrees on the 3rd and a minimum of 18.4 degrees on the 30th. December precipitation measured 4.36" via the Cirrus automated gauge and 4.35" in a manual gauge used for the CoCoRaHS program (which included about 0.10" that fell in the early morning hours on January 1). Snowfall on December 26 totaled 1.3".  The measured peak wind gust was 34 mph on the 20th. Average relative humidity was 80%. Click here for a daily recap on MemphisWeather.net.

MWN Forecast Accuracy

For the month of December, the average temperature error in all MWN temperature forecasts was 2.37 degrees, lower than all available full-range computer model data and the National Weather Service. More than 65% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). For dewpoint accuracy, the MWN forecast averaged 2.70 degrees of error and fell within 2 degrees of the actual dewpoint nearly 55% of the time. Historical accuracy statistics can be found here.

For the year, the average temperature error in all MWN temperature forecasts was 2.22 degrees. 66.8% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. For dewpoint accuracy, the MWN forecast averaged 2.65 degrees of error and fell within 2 degrees of the actual dewpoint over 59% of the time.

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