Fake weather news spread across the internet that the government is secretly spraying poisonous chemicals from jet aircraft to poison us or make us ill. (Getty Images)
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Social media – Facebook more than any other element of it – suffers from countless posts on news, politics, medicine, nutrition, and weather based on bad information.

I’m here to discuss my bailiwick, weather.

Sometimes it’s awful information tied to baseless conspiracy theories such as chemtrails. In this example, thousands of folks believe the government is secretly spraying poisonous chemicals from jet aircraft to poison us or make us ill. The imagined poisons are jet contrails, which is moisture in jet exhaust which condenses in the frigid higher altitudes. The longevity of contrails is highly dependent on humidity levels at those altitudes, and the strength of winds up there.

Of course, such beliefs are based on ignorance of very basic physics and being out of touch with reality as to how the conspirators would escape such effects themselves. Many of these conspiracy theorists think meteorologists are part of their imaginary conspiracy because “We know the truth and are hiding it from the public! Contrails don’t behave like the ones in this picture!”

Yes, they do behave like that. You just don’t know it, theorist.

Allow me to get back to bad weather information not based on scientific illiteracy or politics.

It’s probably a very good thing that public interest in weather is virtually inexhaustible. Weather is a great subject for introducing children and adults to physics without the fearsome equations we deal with in its formal study.

However, the old saying “a little bit of knowledge is a dangerous thing” applies to many Facebook weather posts.

There are countless weather enthusiasts out there. Every one of them with a computer has access to downloading weather models from many government sources. There are sites which can bring a smattering of knowledge as to how to read these models, and most of these sites skip the tougher stuff like the laws of thermodynamics and the awareness of uncertainty which increases both with time and with lack of an understanding of how the atmosphere behaves.

We have weather models which depict precipitation in six-hour increments out to 384 hours. The American GFS model is freely available. Here is an example of what the model is projecting 16 days out in time.

At the time of this writing, the GFS is showing a little light snow over the eastern Great Lakes and Western New York at 7 a.m. on Jan. 26. I hope it’s almost needless to say no meteorologist would attempt to make such a prediction 16 days in advance based on this or any other model.

Some of you are familiar with chaos theory. Basically, the atmosphere is too chaotic further out in time to tangle with precipitation so far in advance. The models and their ensembles (numerous runs of a model, each member with different start up/initial conditions) can often present realistic trends for temperatures and patterns that far out and sometimes even farther out. But the position, strength and impact of such storms so many days out is simply beyond our abilities to predict, and may always remain so.

Here’s another example from the same GFS run which shows a deep cyclone nearby nearly as far out in time. Put those tightly wrapped isobars in front of an amateur enthusiast and you may have the makings of a sensational fake weather post.

“It looks like the Great Lakes could be facing a roaring blizzard by January 24th, with blinding snow and frigid winds!” Then, the poster puts up the link, just like I did.

Some of these amateurs develop huge followings, far beyond any numbers most professionals can draw. The countless storm-lovers crave excitement, and these fakers supply it, by the truckload.

Now and then, one of them goes weird on us and gets into trouble.

A fella in southern California began issuing his own tornado watches and warnings, and the San Diego National Weather Service Office put out a disclaimer about such false warnings in calm language. That sent this wacky guy off the deep end, and he allegedly made terrorist threats again the San Diego NWS. He received a visit from the FBI, which he videotaped for posterity and put on his former website. Facebook has essentially banned him, and I refuse to mention his name. Most of the weather fakers are simply enthusiasts who revel in the excitement they feel and they can create.

Matters may be made worse by professional companies putting out 14-, 30- and 45-day forecasts because they can, even if the forecasts show no skill. The models churn this stuff out, the companies know the public has an appetite for long-range, detailed forecasts whether worthless or not (not to mention the absurd output from the Farmers Almanac), and there’s real money to be made.

In reality, our forecast skills and understanding of the atmosphere are the reasons why folks like the NWS and I stick to seven-day forecasts. There are rare occasions when we may feel some confidence about an eighth or ninth day, but not to the level where we’d feel scientifically competent to forecast precipitation that far out in time on a regular basis.

The basic rule for perusing social media forecasts: Know your source. Know the source’s background and experience. If there’s nothing about the latter on the source’s page, that should be telling you something.

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