Tag Archives: weather models

Believe it or not, some snowstorm forecasts on Facebook are bogus!

Snowfall forecast map from the European numerical weather prediction model run on Dec. 16, 2013 for the forecast period Dec. 22-23. What actually happened Dec. 22 and 23 wasn't even close to this!
Widely shared snowfall forecast map from the European numerical weather prediction model run on Dec. 16, 2013 for the forecast period Dec. 22-23. What actually happened Dec. 22 and 23 wasn’t even close to this!

Winter weather is just around the corner in Indiana, which means so are authentic-looking but bogus long-range snowstorm forecasts on social media.

It won’t be long before we see claims that a storm a week or more away will bring huge snow accumulations. Many will have official-looking forecast maps, like the one above (which turned out to be wrong, by the way).

But these posts won’t be the work of professional meteorologists. Many will be the creations of school kids, passing themselves off as weather experts.

This is Winter Weather Preparedness Week in Indiana, so it seems like a good time to prepare readers for the ominous-looking but unreliable snow forecasts they’ll soon see.

To understand what amateur weather enthusiasts put on social media, it helps to know something about the computer programs that professional meteorologists use to guide their forecasts. These programs are called numerical weather prediction models. They simulate Earth’s atmosphere by describing it in a complex series of very complicated mathematical formulas.

The programs built on these formulas run several times a day on supercomputers around the world. Much of the output of these programs is available on the Web, in both numeric and graphical form.

The output of computerized atmosphere models is inherently inaccurate for several reasons, including:

  1. It’s not yet possible to completely describe our chaotic atmosphere in mathematical equations and
  2. The programs don’t have access to enough data about what our atmosphere is doing at the time they run (e.g. what the temperature, wind speed and wind direction are 10,000 feet over any given part of the planet).

Nonetheless, these programs kick out predictions of what the weather might be at any location at any time, as far in the future as 16 days, despite that fact that no computer or human can reliably forecast the weather that far in advance.

Now, imagine a young weather enthusiast who craves attention and loves snowstorms (because they get him out of school). When he sees an indication of heavy accumulations in the output of a single computer model, he might paste that model’s map into a Facebook post in which he writes a dire forecast of impending doom. Such an amateur forecaster might not be aware of (or care about) the model limitations described above. But she’ll love all the “likes” and shares her post receives!

So how do I know what to believe? First, I’m automatically suspicious of any social media post that forecasts specific snowfall amounts more than a couple days in advance. Second, I ignore any forecast that doesn’t come directly from professional sources I trust, such as:

  • The National Weather Service.
  • Local, degreed broadcast meteorologists.
  • Certain commercial weather forecasting companies.

If that ominous snowstorm forecast didn’t come from one of the above, I won’t share it on social media. I hope you’ll join me in that practice.

Irresponsible social media weather hype has real consequences

(Jan. 4, I edited the post below — which originally appeared Jan. 2 — to include a citation of an excellent blog post by well-known, Alabama broadcast meteorologist James Spann)
Distributing weather hype -- long-range forecasts of storms based only on model data -- is irresponsible
As a follow-up to a Facebook post I shared earlier today on the “Radio W9LW Weather” Facebook page, I want to make a few things clear to the readers of this blog, the Facebook page and the RadioW9LW Twitter feed.

I consider it irresponsible to publish long-range forecasts of storms on social media. It doesn’t matter what some computer-driven, numeric model of the atmosphere says might happen two or more weeks from now. It doesn’t even matter if more than one model agree.  All that matters to me are the forecasts of highly trained meteorologists, who combine information gleaned from models with other knowledge to responsibly forecast the weather over a reasonable period (I consider anything specific more than seven days from now to be unreasonable). Yes, it might turn out that some weather enthusiast’s favorite model was “right” to forecast a heavy snow event four weeks from now. So what? That doesn’t make that enthusiast’s distribution of that model’s data responsible.

Alabama broadcast meteorologist James Spann

As well-known, Alabama broadcast meteorologist James Spann writes in his blog, “Most of the 2-3 week ‘forecasts’ are done by people not qualified to forecast the weather 2-3 days in advance. Most are young weather enthusiasts that, in their love for ice, snow, or severe weather, just ‘wishcast’ by throwing out model maps they have pulled down on various sites promoting the weather they love and desire without understanding the limitations of using those products, or the science behind them” (italicized emphasis added by me).

What’s the harm? As Spann puts it, “a banner headline about a snow storm in three weeks in the southern U.S. can create a societal impact.” For example, people unnecessarily reschedule needed medical treatments or important travel. These things really happen, because members of the general public don’t know how to distinguish reliable, science-based forecasts from the “wishcasts” Span describes above.

Plus, people deluge professional meteorologists (like Spann and National Weather Service staff members) with messages asking whether the irresponsible social media forecast is valid, wasting valuable time.

We are blessed in the United States, however, with the rights of free speech and freedom of the press. Therefore, I do not support any form of regulation that would restrict people from irresponsibly publishing long-range, model-based forecasts on social media. Nor would I support any attempt to restrict access to model data, to make it more difficult for people to share it irresponsibly. The best ways to reduce such irresponsible use of social media are to a.) refuse to share it and b.) attempt to help members of the general public understand the limits of the science.

Now, a little about me, my social media posts and why I do what I do:

I am not a meteorologist. If you’ve paid close attention to the weather information I’ve shared, you’ll see that anything related to forecasts is attributed to very reliable sources, most often the National Weather Service (NWS). I do not create my own forecasts and I refrain from commenting on the likelihood of some weather phenomena occurring, except to relay confidence levels of NWS meteorologists and probabilities published by, for example, NWS Storm Prediction Center (SPC) meteorologists. For example, you won’t see me publish anything like, “The SPC has this area under a moderate risk, but I’m not impressed by (enter some atmospheric measure here).”

I consider myself a journalist. I have worked in the past as a professional journalist and continue to use the skills I gained in that career in my current career as a public relations consultant. That’s why you’ll see attributions in my posts, so you’ll know who created the information I share. It’s also why you might recognize the use of Associate Press style in my posts.

I am a trained, volunteer SKYWARN storm spotter for the National Weather Service. In addition to the basic training that the NWS provides annually, I attend a wide variety of other seminars, at my personal expense, to learn more about meteorology. The knowledge I’ve gained helps me be a more effective storm spotter and it helps me better interpret meteorological information. It does not, however, qualify me to forecast the weather. Forecasting requires much more than knowing where to find map graphics based on computer-run numeric models of the atmosphere.

I am all about weather safety. It’s why I invest so much of my life in storm spotting, weather education and writing about weather. I want to do what I can to help protect my neighbors and others from severe weather and to help the NWS issue effective warnings.

Are you with me? Post a comment, and/or use the sharing buttons to share this “manifesto” with others.