Wednesday: 2 January 2013
It’s The Month of December, Number 83 in a series. That also means it’s 2013, so Happy New Year!
Here are the usual temperature anomalies products, at the National Weather Service Climate Prediction Center.
As in November, much of the western US showed anomalously high temperatures. In December, though, nearly the entire country had anomalously high temperatures. Temperatures were 6-8 degF higher than normal in IL, IN and much of OH and TN. They were just slightly lower in the rest of the eastern US. This was particularly true during the first 2-3 weeks of December.
|We find the National Weather Service Climate Prediction Center’s precipitation plots here. |
There was some relief from November’s near total dry conditions, in December. Much of the eastern and western US received normal to above normal rainfall. However that left the already drought-stricken southern states centered around Texas again abnormally dry.
For the Athens, GA area:
Here is a plot of our daily temperatures excursions in December, along with precipitation amounts as experienced in Wolfskin. Temperatures declined in steps, much as they did in October and November:
The average monthly temperature for December was 49.8 degF, more than 4 degrees above normal. We had 8 days more than 1 standard deviation above normal highs (5.6 normal), and 2 days more than 1 standard deviation below normal lows (4.3 normal). Definitely skewed high in December. In fact, with November’s temperatures lower than normal, the average mean and lows for December were 2-4 degF higher than November’s, one of those weird month reversals that happens now and then.
The monthly histogram below shows the breakdown of high and low temperature range counts from December 1948 on. Most temperature ranges individually just barely showed significance (check out the error bars set at plus one standard deviation).So we had 5 days above 70, but average is 2 +/- 3 so by itself, not impressive. We had more daytime temperatures smack in the middle range, 50-59 degF, but that again is just barely covered by the error bar. However, it’s clear that there is a trend - the number of days average to warmer clearly come from the days in the cooler ranges <50. Similarly for the nighttime lows.
The figure below shows the Athens precipitation data which are official for our area. As usual the green line shows our actual rainfall, the red shows the average accumulation expected. The black dots are rainfall over the last 20 years, the vast river of peach shows the standard deviation, and that rare blue color at the end shows we got a 1 SD surplus of rain for December.
Our total out here was 6.20", and in Athens (shown here) it was 5.86". 3.73" is normal for December, so we were well above normal. Most of the rain fell after that first two weeks in December.
I have a feeling that places farther north really noticed the warmer December temperatures. Here, not so much. It may get cold here in December, and we’ll notice unusually cold temperatures. If it’s on the warmer side of average though, most people here won’t notice that.
What is the neat prognosticator telling us? These much warmer temperatures look to persist over the next month for the eastern US. For northeast Georgia, it looks like warmer than normal temperatures for the next three months. This bodes ill for snow. Precipitation is predicted to be above normal in January and February, and then equal chance of above/below normal in March.
The folks at CPC have a version of PDF or HTML that is much different from their previous presentations, but at least it’s there and the link isn’t broken.
As of Dec 31, ENSO neutral conditions continue. It continues to seem like no El Niño will develop this winter.
As of Dec 25, the US Drought Monitor continues to have us in extreme to exceptional drought, depending on where you are in Georgia. Much of the US continues to be under at least abnormally dry or moderate drought classification, with a lot of the country in severe or extreme drought. However the forecast for the southeast suggests at least some improvement, if not a reversal in the next three months.
NOAA’s Monthly State of the Climate product for November is available, and includes discussion of the immediate aftermath of Hurricane Sandy. The summary for 2011 regionally, nationally, and globally is also available. Soon we’ll have a discussion of the weather of 2012.