Tuesday, June 4, 2013

May 2013 Climate Data and MWN Forecast Accuracy

Like April, May was cooler and wetter than normal. In fact, the month was very rainy with the May precipitation total of 10.75" ending up as the 4th wettest on record.  Temperatures so far in 2013 are averaging about one degree below normal, while the year has been very wet with 10.30" of rain above average.  May started with record breaking low temperatures early in the month.  There were two severe weather episodes - on the 21st (which featured some high wind but mainly flooding rain) and 31st.  The last day of the month had a few severe thunderstorms and one tornado.  The tornado was an EF-1 with 95 mph wind that touched down for 4 minutes just after 6am four miles northwest of Covington, TN in Tipton Co.  Two homes sustained significant damage and a shop was destroyed. Climate details for May can be found below.

Memphis International Airport, Memphis, TN

The average temperature for the month of May was 69.7 degrees, or 2.0 degrees below normal. The average high temperature was 78.7 degrees and the average low was 60.6 degrees. The coolest temperature of the month was 36 degrees on the 4th, while the highest temperature was 89 degrees on the 29th. Record low temperatures were set on the 3rd (37) and 4th (36).  The low of 36 on the 4th also set a monthly record low for the month.

Precipitation for the month totaled 10.75", which was more than double the average monthly rainfall (5.50" above average). There were 10 calendar days with measurable rainfall, five of which recorded at least 0.5" and three which saw 1" or more. The maximum 24-hour rainfall was 4.18" on the 21st, which also set a daily record. The peak wind gust was 40 mph from the south on the 31st with an average wind speed for the month of 8.1 mph. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN

The average May temperature at Cirrus Weather Solutions was 69.0 degrees with a maximum of 89.2 degrees on the 19th and a minimum of 34.9 degrees on the 4th. May precipitation measured 9.69" via the Cirrus automated gauge and 10.10" in a manual gauge used for the CoCoRaHS program. The measured peak wind gust was 23 mph on the 30th. Average relative humidity was a sticky 75%. Click here for a daily recap on MemphisWeather.net.

MWN Forecast Accuracy

For the month of May, the average temperature error in all MWN temperature forecasts was 2.27 degrees, lower than all available computer data models lest one (the NAM) and the National Weather Service forecasts. Nearly 66% 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 2.55 degrees error and fell within 2 degrees of the actual dewpoint over 58% of the time. Historical accuracy statistics can be found here.

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