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

Friday: 21 December 2012

Red Sky at Night  -  @ 07:44:22
Happy Winter Solstice - looks like we went over the line about an hour ago.

We've had some rain in the last week or two - seems like tons, but it's only 3.20" which isn't even quite a December average yet. Nonetheless it's far more than we've had for the past few months, and we stand at 33" for the year so far. Out of 48" normal rainfall, we're still below 70%.

So the rain ended yesterday at 5:30pm, which not coincidentally was sunset, and the still overcast sky turned a distinct red. The drab leaf cover and surroundings lit up with a rusty hue. Normally my camera is a little weak on capturing red faithfully, but this is pretty close. We're looking east southeast here.

Here's the more normal appearance from this morning. Notice the remaining greenery. There have been no changes in camera settings or post photo workups.

Here we're looking more southeast. You can tell I haven't pulled a fast one with a filter or color adjustment - the green winter vegetation is still bright green in startling contrast with the overall red.

The sky doesn't look so red in the photos of the woods above, because it was past sunset with overhead clouds, and getting dark. All those photos are long exposures, and I think the sky looks more or less normal.

Here's what it looked like when I actually photographed the sky. Much shorter exposures, which made everything else dark. But the sky hasn't washed out and looks much redder. Looking northeast now.

Looking west here.

And here's a comparison photo taken a few minutes ago under normal conditions:

This has happened a couple of times before, so it's not an unprecedented phenomenon. I showed the photos last night at training, and Charleen showed me one *she'd* taken about the same time, about a mile away. So I wasn't the only one to notice!

Now sunset is pretty clearly a requirement for this. However, we have had many sunsets when it's been cloudy before, and nothing like this happened. Things usually just get dull and then the light goes out. There needs to be something more to explain this.

I think what happened was that the rain ended pretty much at sunset, followed closely by a strong cold front. That cold front hadn't reached us yet, so we still had overcast skies, but it cleared the skies farther southwest of us. That permitted red sunset light to enter this clouded region, bounce around, maybe even get further filtered of the bluer components, and then reflect back down on us from our overhead clouds.

We're getting pretty heavy winds and cold temperatures from that cold front, by the way. It started passing over us an hour or two after sunset and the skies cleared very very quickly.

Friday: 7 December 2012

The Month of November  -  @ 08:05:16
It's The Month of November, Number 82 in a series. We were just a degree or so below normal, but with extremely dry dry conditions after Oct 2.

Here are the usual temperature anomalies products, at the National Weather Service Climate Prediction Center.

After three months in a row of higher than normal temperatures, the West expanded enormously in November. An enormous portion of the US ended up 4-10 degF higher than normal. Without exception, the eastern part of the country was below normal in temperatures, though not extremely so except along the Atlantic coast.

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

This month's green and brown pattern is very close to opposite of last month's. I can't recall seeing so much brown over such an undisputedly large and uniform area. Some of this is that the calendar month was sandwiched perfectly between two extreme events: Sandy at the end of October, which if included would turn the northeast green, and the atmospheric river, which just begins at the end of November.

One portion of the country continued with the same routine as in October, and that's the upper midwest. Most of the Dakotas, WI, MN, MI, NE, and IA continued in drier than normal weather.

For the Athens, GA area:

Here is a plot of our temperature swings in November, along with precipitation amounts as experienced in Wolfskin. Temperatures declined in steps, much as they did in October:

The average monthly temperature for November was 51.4 degF, nearly 4 degrees below normal. As we will see this was mostly due to nighttime lows. Even so, we had only 3 days more than 1 standard deviation above normal highs (5.4 normal), and 5 days more than 1 standard deviation below normal lows (4.8 normal). Nothing exceptional there, and we broke no records.

The monthly histogram shows the breakdown of high and low temperature range counts from November 1948 on. There was nothing very significant in the daily high temperature ranges. The number of days with 60-69 degree highs just flirted with being more than normal. As in October, it was the much larger than normal number of mid-range low temperatures that made November so cool. There were nearly twice as many nights in the 31-40 degF range, and many fewer warm nights.

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 nasty mustard color shows how far below one standard deviation we were at the end of the month.

Our total out here was 1.09", and in Athens (shown here) it was 0.96". 3.82" is normal for November, so we were extremely. There was virtually no rain after mid-November.

Let's look at the long term cumulative rain log again, since we're coming down to the annual wire. You'll recall that I project what our rainfall should be if we started taking account of it in January 2005, nearly eight years ago.

The blue line is the most interesting, as it shows difference between the accumulated average and the accumulated actual. As you can see, we're now in our second extreme drought in eight years, and we've just about returned to the low point we experienced in September 2009. We never really recovered full rainfall between mid-2009 and mid-2011.

Perceptions of drought around here are pretty limited to people who watch the weather, and maybe those involved in agriculture. This is in contrast to the 2007-2009 drought, when many more became aware of the profound level of drought. There are any number of reasons why this could be so, and those reasons probably deserve their own post.

Prognosticator stuff:

What is the neat prognosticator telling us? For northeast Georgia, We might expect greater chance of warmer temperatures for December, and then normal temperatures through February. However, last month predicted normal to warmer temperatures in November, and that didn't happen. Precipitation is predicted to be above normal in December, and then at least normal through February, but we're certainly not seeing it 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 Dec 3, ENSO neutral conditions continue. It now sounds like no El Niño will develop this winter.

As of Dec 4, 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.

NOAA's Monthly State of the Climate product for October is available, and includes discussion of the immediate aftermath of Hurricane Sandy. The summary for 2011 regionally, nationally, and globally is also available.

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