Tuesday, December 10, 2013

November Climate Data and MWN Forecast Accuracy

The big story for November seemed to be intrusions of cold air on a few occasions, which left the area under Canadian high pressure and very cool temperatures. Overall temperatures and precipitation were well below average for the month, making for a cold and dry November.  The average temperature for meteorological fall (September-October-November) was near normal, but precipitation was below normal this year. For 2013 year-to-date, temperatures are averaging 63.9 degrees, or 0.8 degrees below normal.  Climate details for November can be found below.

Memphis International Airport, Memphis, TN

The average temperature for the month of November was 49.2 degrees, or 4.0 degrees below normal. The average high temperature was 59.0 degrees (3.6 degrees below normal) and the average low was 39.3 degrees (4.4 degrees above normal). The coolest temperature of the month was 21 degrees, reached on the 28th, while the highest temperature was 77 degrees on the 17th. There were nine days which saw low temperatures below 32 degrees and three days in which the high did not reach 40.  The high of 35 degrees on the 27th set a record (1938) for the coolest maximum temperature on record for that date. There were only six days in which the mean daily temperature was greater than 2 degrees above average.  For the period of meteorological fall, the average temperature was 64.0 degrees, which was 0.2 degrees below normal.

Precipitation for the month totaled 2.67", which was 2.82" below the average monthly rainfall for Memphis International. There were eight calendar days with measurable rainfall, but none which saw 1" or more.  Through November 30, annual precipitation at Memphis is 54.61", which is 6.67" above the 30-year average. During meteorological fall, precipitation totaled 8.66", which was 3.90" below normal.

The peak wind was 37 mph from the north on the 26th with an average wind speed for the month of 7.9 mph. The average relative humidity was 61 percent and average sky cover was 50 percent. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN

The average November temperature at Cirrus Weather Solutions was 47.5 degrees with a maximum of 77.3 degrees on the 17th and a minimum of 17.9 degrees on the 28th. There were 11 days with lows below 32 degrees and 3 days with highs below 40.  Monthly precipitation was lower than at the airport and measured 2.52" via the Cirrus automated gauge and 2.59" in a manual gauge used for the CoCoRaHS program. Maximum daily precipitation was 0.77" on the 17th on the automated gauge. For the year, the CoCoRaHS gauge at MWN has recorded 51.52" of precipitation, or just over 3" less than the airport. The measured peak wind gust was 22 mph on the 12th. Average relative humidity was 73%. Click here for a daily recap on MemphisWeather.net.

MWN Forecast Accuracy

For the month of November, the average temperature error in all MWN temperature forecasts was 2.08 degrees, lower than all available computer data models and the National Weather Service forecasts. MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). Over 66% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. For dewpoint accuracy, the MWN forecast averaged 2.87 degrees error and fell within 2 degrees of the actual dewpoint over 51% of the time. Historical accuracy statistics can be found here.

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