Sharp February warming: Is it weather or climate? Or is it both?
To say it’s hard to tell is a scientific understatement. There is the irrefutable footprint of a warming climate when averaged globally. Winters have been warmer, again on average, across the United States for many decades.
Note that there are no regions in the lower 48 states that have had mean cooling in that time period since 1970. So, it’s fair to say the background warming is proven beyond a reasonable doubt. However, as I’ve written many times, that proof does not extend to every individual weather event involving extreme warmth as being dominantly driven by climate, rather than short-term weather phenomena.
The most recent example of extreme warmth came this past Saturday, especially in the southern plains. Amarillo, Texas, sits at an altitude of 3,770 feet above sea level. On Saturday, the high was a record 89. By Monday morning, the low was back to 26, (normal for the date) so that was clearly classifiable as an extreme, short-lived weather event.
Amarillo wasn't alone. In Oklahoma City, the temperature hit 89 degrees. In Lubbock, Texas, it rose to 91 degrees. And in San Angelo, the high was 93 degrees. According to the Oklahoma State Climatologist, a town named Mangum in Oklahoma hit 99 degrees, which was the hottest winter temperature (December through February) ever recorded in that state. And on Sunday, records were set at Charlotte and Raleigh, North Carolina, at 80 and 83 degrees, as well as in Richmond, Va., at 82.
Climate Matters, using official NOAA data, reports that so far this year daily record highs are outpacing record lows 3 to 1 nationwide. Last year that ratio was 5 to 1.
NOAA climate records show this ratio of record highs to lows has increased each of the last four decades. As for this month, through Sunday, Feb. 12, the ratio has been an incredible 120 to 1. Since that number changes every day, you can track the latest number of records from NOAA.
Despite all that, I cannot categorically tie the extreme warmth this month to a warming climate.
I suspect there is a connection, but it is still almost impossible to gauge that connection numerically. To my knowledge there is no empirical data to support an estimate of the tie-in for such an individual spike. Of course, there were many spikes prior to the accelerated warming in recent decades, including all-time record high and low temperatures in a few years during the 1930s (sometimes called the “dirty '30s”) partially due to the Great Dust Bowl. But there is no getting away from the fact that the up spikes are increasingly dominant around most of the world.
There is a theoretical possibility – emphasis on theoretical – that the rate of warming might be slowed during the next 50 years with some assistance from the sun. There is a statistical correlation between longer periods of minimum sunspot activity and cooling on the earth. A period known as the Maunder Minimum, from the early 17th century, lasted around 70 years and coincided with what’s called the Little Ice Age. During that time, there was exceptional cooling across most of the northern hemisphere, when there were virtually no sunspots, based on astronomical reports of the time. It is one of the grand solar minima known to have been closely matched to a cooling period.
We have been in a period of reduced sunspot activity since 2007, with our most recent maximum being exceptionally unimpressive. And there is some evidence such a grand minimum may soon be upon us. The magnetic fields associated with what few sunspots there are have been weaker than normal for around 15 years.
However, there are two things to keep in mind on this issue. One, it remains to be seen whether we are truly entering a grand minimum. Two, global warming has continued even during this time of very low sunspot activity. Here is an excellent backgrounder on this topic.
Most physicists believe a grand minimum would slow, but not stop, the warming. As of now, it’s clear human activity is outpacing these theoretical effects of very low sunspot numbers. That activity wasn’t in the background during the Maunder Minimum to mitigate the cooling.
Now, let’s get back to the near-term meteorology. By this weekend, a warmup on a meteorological time scale will be setting up. Confidence on this is high, as shown at left in the 6-10 day outlook from the National Weather Service Climate Prediction Center, in which a large part of the east has an estimated 90 percent probability of above average temperatures.
Here is an ensemble of 21 different runs of the American GFS model showing the upper-level flow at 18,000 feet going out 16 days. Warmth is associated with the warmer colors, where a high-pressure ridge is developing. After a chilly couple of days this week, the pattern change begins.
If you animate the ensemble, you’ll note those contours start to dip again near the Great Lakes around Feb. 25. That’s when we’ll find temperatures slipping back toward more seasonal levels.
The dip looks unimpressive this far out in time. Part of the reason for that is extremes tend not to show up in ensembles after 10 or 11 days because each of those 21 members spread apart from one another more late in a run. It may end up being minor cooling or sharper cooling. We just don’t know yet.
Back in mid-autumn I had been expecting a more typical winter with a more typical number of ups and downs. Thus far, the ups have outweighed the downs.
It has not been as mild as last winter, with the super El Niño. And there have been some heavy lake snows to the south, including one fairly extreme event in the Southtowns. But it has been milder than average the majority of the time, and Buffalo is 25 inches below average for snowfall as of this writing. North of Buffalo, snowfall has been even more sparse.
All that said, the experimental 46-day version of the European ensemble and other extended-range guidance suggests we shouldn’t expect a consistent early spring, at least not in March. The European shows a high-amplitude chain of pattern changes with lots of ups and downs. There may be greater than usual potential for severe weather in the southern plains and the south, some very warm periods, and some colder stormy periods with more nor’easters from time to time.
March is often a very active weather month, and I think this year will keep meteorologists very busy.
Story topics: By Don Paul