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

Sunday: 4 May 2014

The Month of April  -  @ 13:42:51
It's The Month of April, Number 99 in a series. I've still only seen two box turtles (one dead), and attribute this to an odd occurence of extremely dry weather once temperatures have warmed up. Box turtles like warm and wet during the spring, but this just didn't really happen.


Here are the usual temperature anomalies products, at the National Weather Service Climate Prediction Center. Displayed are the mean temperature anomalies, not the absolute temperatures.

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

Anomalies in temperature became much reduced in April. It was still considerably hotter in locations in the southwest, and continued quite a bit colder in Wisconsin and Minnesota, but extremes were much less widespread.

The southeastern states were a bit warmer in April, a switch from March. Most of the central US was just a degree or so cooler than normal, as was the Northeast US.

The National Weather Service Climate Prediction Center's precipitation plots are no longer being updated here. The closest I can find to the old familiar anomaly map is accessible from here. It seems a much less flexible and intuitive presentation, but maybe that's just me.

It's hard to compare the rainfall anomaly map in March with that in April, but it looks like much drier weather extended itself somewhat in the West (excluding Washington state). In contrast much of the eastern US received higher than normal rainfall, but there are certainly small regions that did not.

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 columns are Wolfskin rainfall measurements. The black line is the 30-year average daily temperature, which is steadily moving upward as expected.

In April, as in March we had quite a fluctuation in temperatures - three extended instances of several days of warm, pleasant days. Those were punctuated with two short periods of colder than normal temperatures centered around periods of rainfall.

Here in the Athens area, we were somewhat above normal in temperatures in April. The Athens area mean temperature during April was a little less than one degree above the average 61.7F. We didn't break any record highs or lows, but did come within a degree of matching the cold record of 30F on April 16. It was just a couple of days after that the I found the dead box turtle.

We had 7 days more than 1 standard deviation above normal highs (average is 4.9 days). We had 4 nights with temperatures more than 1 standard deviation below normal lows (average is 5.3 nights). By these criteria, temperatures in April tended warmer.

The monthly histogram below shows the breakdown of high and low temperature range counts from April 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.

Only the high temperature range of 80-89F had barely significant deviation above normal events in that temperature range. We had four extra days in that temperature range.

Below is the monthly accumulation of rain in Athens, GA. The river of peach is the long term standard deviation of all the daily black dots in the last 15 years, and the red line is the daily cumulative average. We're the green line this year, and for almost half the month it cradled that surplus of blue above the one standard deviation mark.

We had two significant periods of precitation in April, each contributing a couple of inches of rain, and elevating us briefly into the blue region of surplus. The average April rainfall is 3.15", and we had 4.17" in Athens and 4.77" out here in Wolfskin. We're still a bit below average for this time of the year, but April did help.

Prognosticator stuff:

What is the prognosticator telling us (as of April 29)?

The drought outlook over the next month and season is for continued dryness in the West, Southwest, and South west of the Mississippi. That could change, depending on the possible El Niño emergence.

In the east and southeast, we're scheduled for more rain over the next few weeks, subsiding into some kind of normal precipitation regime. Temperatures will be higher than normal for the first couple of weeks, and then picking up again a month or two down the way. The eastern US does not seem to be in danger of drought over the next three months.

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.

Not much change since the last summary. There has been a very large Kelvin wave that has preceded such El Niño events as 1982 and 1998, but surface temperatures in the Pacific have not risen above neutral levels yet. As of 28 April, ENSO neutral conditions continue, and are expected to remain neutral, now through the Northern Hemisphere spring. The planet has remained ENSO neutral now for 23 months. The last time we had such a lengthy period without an El Niño or La Niña must at this point have been in the 1990s.

(There continue to be signs that an El Niño may be gearing up for later in the summer. 50% chance is the likelihood, with a 10-20% chance that we'll have another La Niña.)

NOAA's Monthly State of the Climate product for March is available.

Summarizing from what I see on the map: Globally March 2014 was the fourth warmest ever recorded. The Arctic sea ice extent in March was the lowest recovery since satellite records began in 1979. Alaska had its third warmest three-month beginning of the year (behind 1981 and 2001). In contrast, much of North America, excepting the western US, experienced the coldest March since 2002.

Here is the final annual State of the Climate report for 2013 regionally, nationally, and globally. It's pretty US-centric, but there are comments for climate globally too.

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