Wednesday, November 3, 2010

Damp, then chilly, weather - a sure sign of fall

With a couple of days of cool and damp weather nearly behind us and our first blast of cold late autumn-like air just around the corner, it is definitely feeling like fall! I don't think too many people are complaining about the recent rain considering the lack of it the past couple of months. It has kept temperatures cool and, honestly, was pretty poorly forecast by the computer models until it was already here.

The clouds clear out this evening as the upper-level low pressure system responsible for the rain moves farther south into the Gulf of Mexico and a huge upper-level trough dives south towards the region from the north. This trough will settle in Thursday and Friday before moving east this weekend (see computer model graphic above with the trough [red line] positioned just to our east on Friday morning). A trough in the upper levels this time of year means only one thing = much cooler weather! Consequently, I expect high temps to struggle to reach 60 on Thursday and remain in the lower half of the 50s on Friday. While 30s are expected across the region Friday morning, Friday night's low will likely be the coldest yet this fall with nearly everyone dropping below freezing. I am forecasting 35 at the airport and in downtown Memphis and 29-32 in the suburbs (perhaps 26-27 in low-lying colder rural areas).

A warm-up begins this weekend as high pressure moves east and brings southerly wind back. Temps should rebound into the 60s by Sunday and near 70 next week. No rain is in the forecast after this evening for the next 5-6 days. Visit the MemphisWeather.net forecast for complete details.

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Tuesday, November 2, 2010

October Climate Data and MWN Forecast Accuracy

Memphis International Airport, Memphis, TN
October is generally a very pleasant weather month in the Mid-South, with moderating temperatures and dry conditions for the most part. While the dry weather of previous months continued, temperatures averaged above normal as well, with two temperature records being set or tied. The very dry conditions resulted in the metro area being classified as being in a "severe drought" at the end of the month.

For the month, the average temperature was 66.1 degrees, which was 2.3 degrees above normal. The average high temperature was 79.1 degrees and the average low was 53.1, with 2 days reaching a high of 90 and 91 - both of which tied or set record highs for the date (9th and 10th, respectively). The minimum low temperature for the month was 38 degrees on the 30th.

Precipitation for the month of October totaled 2.04", or 1.27" below the normal of 3.31". There were just 3 days with measurable rainfall though, as the maximum one day total was 1.65", or over 80% of the month's total. There was one day in which thunder was recorded (24th). The peak wind gust was 48 mph on the 25th, while the average wind speed for the month was 5.6 mph. Click here for a daily statistical recap for October.

Bartlett, TN
Bartlett also saw a very warm and dry month. The average temperature for October at the WXLIVE! station in north Bartlett was 61.6 degrees with a maximum of 92.9 on the 10th and a minimum of 29.3 degrees on the 30th.

October precipitation ended up well below normal with a precipitation total of 1.73" and only 5 days of measurable rainfall. A co-located manual gauge used for the CoCoRaHS program measured 1.75" in October. The peak wind gust was 34 mph on the 26th. Average relative humidity was 60%. Click here for a daily statistical recap on MemphisWeather.net.

MWN Forecast Accuracy
For the month of October, the average temperature error in all MWN temperature forecasts was only 2.41 degrees, besting all compared computer models, including the National Weather Service, by 6% or more. Over 60% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. MWN's forecasts extend out five periods (or 2.5 days). For dewpoint accuracy, the MWN forecast was the second best of the data sources at 3.06 degrees average error and was within 2 degrees of the actual dewpoint over 50% of the time. More detailed accuracy statistics can be found here.

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