Wednesday, October 3, 2012

September 2012 Climate Data and Forecast Accuracy

A break in the heat that has resulted in 2012 being (year-to-date) the warmest on record came after the first week of September when temperatures reached the upper half of the 90s for 7 days straight.  A cold front that dropped the high 20 degrees ended the run of 90s, probably for the year.  For the month, the average temperature was almost exactly average, while precipitation was well above normal and welcomed.

Through September 30th, the average temperature for 2012 of 69.9 degrees is 3.8 degrees above normal, beating the previous record though the end of September by about 1.5 degrees (2007, +2.4 degrees).  Drought conditions abated somewhat with local and upstream rainfall and 2012 is no longer among the top 10 driest years on record.  The Memphis metro, with the exception of northwest MS, is classified as being in a severe drought, down from extreme to start the month. Northwest MS remains in an extreme drought.

Memphis International Airport, Memphis, TN

The average temperature for the month of September was 75.3 degrees, or 0.1 degrees above normal. The average high temperature was 84.7 degrees and the average low was 65.9. The coolest temperature of the month was 53 degrees on the 19th and again on the 24th, while the highest temperature was 99 degrees on the 5th.  There were 7 days in which the high reached 90 degrees or higher (each day from the 1st through the 7th).  There were no temperatures records set or tied in September.

Precipitation for the month totaled 7.01", which was 3.92" above average. There were 12 calendar days with measurable rainfall, 3 of which saw totals of 1" or more (maximum 2.24" on the 1st-2nd). The peak wind gust was 47 mph from the northwest on the 7th as a thunderstorm moved overhead with an average wind speed for the month of 7.1 mph. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN

The average September temperature at Cirrus Weather Solutions was 72.3 degrees with a maximum of 98.7 degrees on the 5th and a minimum of 45.7 degrees on the 24th.  September precipitation measured 5.88" via the automated gauge and 6.38" in a manual gauge used for the CoCoRaHS program (including a small amount of rain that feel prior to 7am on October 1). The measured peak wind gust was 30 mph on the 1st. Average relative humidity was a muggy 76%. Click here for a daily recap on

MWN Forecast Accuracy

For the month of September, the average temperature error in all MWN temperature forecasts was 1.94 degrees, lower than all available computer model data and the National Weather Service. 69% 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 2.54 degrees of error and fell within 2 degrees of the actual dewpoint 58% of the time. Historical accuracy statistics can be found here.

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