Native Plants, Habitat Restoration, and Other Science Snippets from Athens, Georgia

Tuesday: 26 November 2013

Lap Warmers  -  @ 07:34:07
With temperatures in the mid 30s and lots of rain, Gene and Colon, our bookends, are working overtime.

This is actually the first real rain we've had since the end of August. I didn't mention that yesterday, when I wrote of receiving half our annual rainfall in 3 months this past summer.

Sunday: 24 November 2013

The Summer Just Past  -  @ 08:20:34
We had a remarkably wet (once in 30 years), somewhat cooler (once in 4-5 years), very humid summer in northeast Georgia.

Here are the usual temperature anomalies, this time for the 3-month period beginning Jun 1, at the National Weather Service Climate Prediction Center. Displayed is the mean temperature anomalies.

Click on the image for the high and low anomaly graphic on a new page:

Much of the eastern US was cooler than average this past summer, especially the central eastern US. Texas and the northeastern US were warmer than usual by just about the same 1-2 degF that the rest of the east was cooler. There were no really sharp gradients in change from place to place.

But the West was warmer to much warmer, by as much as 4 degF in parts of the West. There were unusual sharp gradients, though, in many places, especially in southern California, Arizona, and New Mexico.

The maximum and minimum temperature anomalies (click above figure) show a familiar pattern for much of the US: nighttime lows were warmer while the days were cooler. Often this is due to cloud cover, and certainly that was true for us.

Here is the National Weather Service Climate Prediction Center's anomalous precipitation plot for Jun 1-Aug 31.

West of the Atlantic states and their immediate neighbors, there were numerous areas with around 50-75% rainfall, interspersed with normal to slightly above normal summer precipitation. Central California was more intensely drought stricken, with rainfall amounting to 25% give or take. More abundant rainfall occured throughout the eastern Atlantic states and their immediate neighbors, sometimes up beyond twice normal.

For the Athens, GA area:

Our summer average temperature was 77.2 degF, not quite 2 deg below the long term 78.8 deg average. However, our average high temperatures were 3.1 degF below the usual summer high average of 89.3 degF.

So temperatures in our area were cooler than average, but not by very much. There have been quite a few cooler summers since 1920, somewhere around thirteen, with another dozen or so just about matching our average. So as far as temperature was concerned, ours was about a once in 4-5 years event.

The histogram below shows the breakdown of high and low temperature range counts from the summer of 1948 on. The error bars are just plus/minus one standard deviation, which I arbitrarily set as the limits outside of which are "significantly" anomalous.

The number of really hot days showed a significant decrease by 50% in the 90-100+ degF ranges, with most of those daily highs ending up in the 80-89 degF range. There were no really significant changes in the nighttime lows, though there was a similar trend for a decrease in the number of warmer nights, paralleled by an almost significant increase in the cooler nights.

And so that does bring us to the rain for our area: in short, lots and lots of rain. Official Athens rainfall was 23.08", almost twice as much as the 12.45" Jun 1-Aug 31 normal total. Out here in Wolfskin, we had 26.26".

These totals are greater than any summer since 1920 except for 1967 (27.1") and 1994 (29.4"). This was about a 1 in 30 years surplus rainfall summer.

In this histogram of summer precipitations by summer rainfall totals (1920-present) we are pretty close out there on the right extreme.

It was also, to my mind, a fairly miserable summer. Day after day we had very humid air flowing in from the south or east, with little in the way of cold waves to break up the humidity. With temperatures just somewhat cooler, there was little relief for three months.

Here is a "misery plot," showing the minimum daily humidities during the relevant part of the last three years. I also included a running average, and then colored in the anomalously high humidity days for 2013 in green.

You can see how the green begins just at the end of May, and then continues through August. (The same thing happened to a lesser extent last summer, from August on.) That green represents all those humid days, and I should know! I hiked 110 miles sampling box turtles from June through August, and spent at least 122 hours doing it.

Another way of looking at it is to count the number of points below the 30% humidity line. Between June 1 through August, you'll see no green points (2013), while there will have been plenty of red and blue points (2011, 2012). The usual cutoff for fire weather is 25%, so as you can imagine there were virtually no brushfires this past summer.

State of the Climate

NOAA's State of the Climate product for Summer 2013 is available. It gives a good summary of summer regionally across the US.

Sunday: 10 November 2013

The Month of October  -  @ 11:38:46
I'm late, I know.

It's The Month of October, Number 93 in a series. For us in northeast Georgia, somewhat warmer temperatures and much drier weather continued for the second month in a row.

Here are the usual temperature anomalies products, at the National Weather Service Climate Prediction Center. Displayed is the high and low temperature anomalies.

Click on the image for the high and low anomaly graphic on a new page:

Much of the US was cooler than average, especially west of the Great Lakes, excepting southeastern TX. Southern CA and western AZ were much cooler than normal (for at least the third month in a row), while the Northwest cooled a bit to just about average. The Northeast switched to warmer than normal, as has been true in the Southeast for the last two months.

Again, and for at least the third month in a row, the high and low anomalies graphic (click on above figure) shows that nights were warmer and the days were cooler. This effect was pronounced for most of the country, except for the Northeast US.

We find the National Weather Service Climate Prediction Center's precipitation plots here.

Interesting changes have been afoot! Dry weather has been the rule for much of the edges of the country, with continued development of abnormally dry weather in the Southeast, Northeast, Southwest, and Pacific states. Lots more rain than normal in the north-central US, as well as normal to somewhat above normal rain in the central US. Central CA remained dry for at least the third month.

For the Athens, GA area:

Below is my usual daily rain/temperature plot visualizing the changes in temperatures and precipitation. The spiky lines are temperatures recorded roughly ten times a day, and the lighter blue bars are Wolfskin rainfall measurements.

The black line is the normal average daily temperature, and you can see that we're distinctly on our downward fall toward autumn.

We're within half a degree (slightly warmer) than the October average mean temperature. We were warmer than average during the first half of the month, and then cooler than average for a few days toward the end. The rainfall that began in June and continued through August finally came to an end in September, and this dry period continued in October. We only had two precipitation events resulting in a total of 0.82", while 3.55" is normal. Athens claimed 1.27".

We did not break any records in October. The average monthly temperature for October was 63.4 degF, just 0.4 deg higher than the 30-year average of 63.0F. The high and low averages tell us that we had slightly cooler days and somewhat warmer nights (see the histogram below).

We ended up fewer extreme events in October. We had 3 days more than 1 standard deviation above normal highs, and 3 night with temperatures more than 1 standard deviation below normal lows. We usually have 5 events outside normal ranges for the high and low temperatures, in October.

The monthly histogram below shows the breakdown of high and low temperature range counts from October 1948 on. The error bars are just plus/minus one standard deviation, which I arbitrarily set as the limits outside of which are "significantly" anomalous.

This time the histogram provides an elaboration on our apparently close to normal average temperatures. The high temperature ranges on the left of the figure stay inside the error bars. It's the low temperature ranges that deviate significantly, and these show more warm nights (50s) and fewer cold nights (40s). For us this is usually because of increased cloud cover, and that's interesting because we also had so little rainfall. Lots of clouds, no rain.

And so that does bring us to the rain for our area: in short, not much. 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 22 years, and the river of peach shows the standard deviation.

We finally have a plot that shows a rainfall deficit. Official Athens rainfall was at 1.27", just 36% of normal (September was 60% of normal). Out here in Wolfskin, we had just 0.82", just a quarter of normal.

At nearly 50" right now, we're just above normal rainfall for the year, with six weeks remaining.

Prognosticator stuff:

What is the neat prognosticator telling us? For us here in the southeast, it has been accurate over the last five months for temperature and precipitation.

For us in northeast Georgia it will be warmer and drier for the next three months (NDJ).

As of 9 November (yes, I'm late this month), it tells us in the Southeast that we can expect from several weeks to possibly two months of much warmer temperatures. Maybe in January we'll go back to normal. The picture is quite different elsewhere, so be sure to take a look if you're not close by us.

We supposedly will have higher chances of precipitation over the next few weeks, then normal, and finally low chances for January. I'm not seeing this short period of wetter weather yet.

ENSO stuff:

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 4 November, ENSO neutral conditions continue, and are expected to remain neutral into the Northern Hemisphere spring. We've remained ENSO neutral now for 18 months. The last time we had such a lengthy period without an El Niño or La Niña was before 2000.

NOAA's Monthly State of the Climate product for September is available. In September most of the talk was about higher than normal rainfall in much of the country. Dry conditions continued or developed only for some of the Northeast; the Great Lakes states, and Hawaii. (As we know now, that's going to change in what will then be the October summary.)

And last year's annual report for 2012 regionally, nationally, and globally is also available.

Saturday: 2 November 2013

The Turtles of November  -  @ 08:55:55
Until yesterday, I had only found one turtle in November, on the 8th, and that was the one who started all this off, in 2005.

During the earlier part of the week we had very warm temperatures, with night lows in the 50s. It has been very dry over the last month, with less than an inch of rain since the last week in September. Still, I kept an eye out for turtles most days but found nothing.

Thursday night offered the warmth of an August night, nearly 70 humid degrees, and then yesterday morning we had a pretty good rain. I ran across these two (#88 and #89 of 2013) in the early afternoon, and yes, they are mating.

Given that one must have discovered the other independently, they both must have been out wandering, and I just figured there would be lots of turtles out. No such luck - these were the only two I found.

Of course I've seen them before! Torri was first discovered as the last turtle found in 2011, and then I found her five times in 2012. This was just the second time I'd found her this year, though. She has a rather broad home range that includes most of SBS Creek, the east floodplain, and the north slope. She seems to return to this upper north slope area for her winter snooze - this is where I found her in October 2011.

I first found Austin, the colorful male, early April last year, and then saw him twice more around upper SBS Creek (south). Yesterday's sighting was my first of this year, and he's far afield from where I've seen him before.

We'll see how things go today. It should be warmer than yesterday, with lingering moisture, although at 8am this morning it was 45 degF.

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