hr agdrought 100319 p02

The region is experiencing drought, prompting many cattle operations to feed hay earlier than normal.

ROANOKE -- So which impresses you more: Blacksburg scoring its hottest October temperature in 66 years of official records at 94 degrees on Thursday, or Blacksburg beating out its previous warmest September average temperature by more than two degrees at 71.3?

Similarly, which seems a bigger deal: Roanoke having its second hottest October day in 107 years of records with a high of 98 on Thursday, or having its second warmest September on record with an average of 75.5?

There is no doubt which are the flashier records.

Temperatures reaching 94 or 98 in October are eye popping and jaw dropping. An average temperature of 70-something over a month that’s still mostly summer on the calendar may not even seem all that warm.

But flash isn’t substance. When it comes to any discussion about climate and what it may doing over time, the September monthly records are far more impressive than three extremely hot days in early October.

Thirty days of temperatures averaged together do not, by themselves, constitute “climate.” But comparing those averaged temperatures over many decades of records is climate, and it reveals what appear to be some significant local trends that parallel national and global trends.

For Blacksburg, the three warmest Septembers on record have occurred in the past four years. Five of the 10 warmest have occurred 2002 or later. That bunching toward recent years would be unlikely based solely on natural variability.

With a longer period of record that includes the hot 1930s, Roanoke’s pattern isn’t as stark, but it’s still quite anomalous that September 2019 would rank second warmest, September 2016 would rank sixth warmest and September 2018 would make seventh warmest.

None of this, on its own, absolutely proves or disproves anything about local, regional or global climate. But it is a suspicious trend that seems to align with what has been observed and theorized on a wider level.

Meanwhile, last week’s surge of ridiculous heat in early October was certainly impressive, but it was a flash in the pan, neither an unprecedented nor oft-repeated one at that.

The weather pattern that produced three days of 90s at Roanoke and Blacksburg was almost identical to the pattern that produced similar temperatures a few days later in October 78 years ago.

High pressure was centered on a west-southwest angle from off the Southeast coast into the Deep South, facilitating westerly to southwesterly winds that dried and warmed sloping down the Appalachians, with a slow-moving cold front draped on a southwest-to-northeast angle over the Midwest, Great Lakes and Northeast. The weather maps from last week and October 1941 are amazingly similar.

And so far, there are no other examples of such extreme heat in early October in our local weather records. Roanoke has reached 95 or higher on six October days since 1912, all of them in two years — four in 1941 and two last week. No other weather pattern has got the mercury that high in October, in our backyards, other than those two occurrences.

There is no trend or pattern involving extreme heat in early October to speculate about. So far, we have two examples separated by 78 years, each dependent on basically the same short-term atmospheric pattern.

It was weather, not climate.

For all we know now, last week’s extremely hot days could be the opening phase of a trend. If something similar happens two or three more times in the next 10 to 20 years, we can start to consider that.

But even if our Octobers trend warmer, as the climatology consensus would suggest is likely with global climate change trends, it would probably manifest in more days in the 80s and nights in the 60s extending into October more often, rather than this specific pattern that makes it push toward 100 — and has only happened twice in almost eight decades — repeating over and over again.

Conflating weather and climate is a rampant problem anytime the words “global warming” or “climate change” are spoken in public discourse.

Politicians of all stripes do it with abandon, focusing on the hurricane or snowstorm or heat wave or cold spell of the moment to make their case, whichever direction, not on the big picture of data shifting by decimals over decades. Message boards light up with comments about how the most recent hurricane was obviously caused by global warming or the most recent snowstorm proves it’s all a hoax.

As yet, there is no short-term weather event climatologists have studied and conclusively determined was caused primarily by global warming. There have, however, been events that have been deemed after extensive study to have been made, in some way, more intense or more likely by climate change, affecting things like higher waves, heavier rainfall and higher sustained temperatures over time in a lengthy drought or heat wave.

You can agree or disagree or expound on or argue with any of that. But the starting point is measured data over a multitude of locations over a long period of time, not whatever it is doing outside your window right now.

Meteorologist Marshall Shepherd, a University of Georgia professor and the former president of the American Meteorological Society, likes to say that “weather is your mood, climate is your personality.”

Another way to look at it is that weather is an inning of baseball, climate is a multi-game series. Your team winning the sixth inning 7-0 matters little if the other team outscores yours 1-0 in the other eight innings and wins the other two or three games of the series, also.

Even a losing baseball team has a big inning and even a victorious game now and then. So we’re still due for rallies of heat, cold, wet, dry and everything in between, whatever history’s climate record turns out to be.

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