Why You Can't Always Trust Social Media For Your Winter Storm Forecasting

Snowfall Forecasts On Social Media May Mislead

Without fail, during the winter months, social media can become flooded with snowfall forecasts showing enormous totals. But most likely these model runs are too far out to be accurate, and they can be extremely misleading.

While these models can give you a clue that something is coming, each model run can widely vary from one to the next. That's why it's important to take these forecasts with a grain of salt.

Let us try to help you decipher a trustworthy social media post from one that's just trying to create hype.

(MORE: Winter Storms 101)

Most snowfall forecasts aren't accurate more than three days out

Advance warning that a big snow is heading your way is understandably necessary for proper planning and preparation. However, the reality is that even the best forecast models can struggle with pinpointing the exact forecast sooner than one to three days before an event.

Our eagerness to know what will happen can be fueled by the computer models that go viral on social media. They show snow amounts so high that we wonder if this will be another "blockbuster snow event." The bright pink and purple colors grab our attention and we start believing we will be held hostage in our homes from snowdrifts as high as our rooftops.

But let's be real: 99.9% of the time, that just doesn't happen.

There's nothing that can be done about these maps; they will never disappear from social media. But we can do our part by not buying into what social media grabs onto and not spreading them like a nasty virus.

Meteorologists often pick up on trends that there will be a significant winter storm within the next week or so, but knowing exactly where the highest amounts of snow will fall is nearly impossible at this point. For example, we know it will impact the Northern Plains and upper Midwest, however, we can't tell you exactly how much snow will fall in Green Bay.

So instead of showing specific details, forecasters usually just give an early heads-up that we are watching for a particular storm in a general time frame. This is typically followed by the meteorologist explaining that the forecast will most likely change, and we will provide more details as they are available.

Why those snow details are hard to predict

There are several reasons why those all important, fine details are difficult to pinpoint.

The weather disturbances triggering the development of a potential winter storm could be thousands of miles away. That means they may be traveling over a more data-void region such as the Pacific Ocean before reaching the U.S.

Without this critical data, numerical forecast models could have quite a bit of difficulty figuring out the important details of how a winter storm may come together from the budding disturbance(s).

Without a disturbance fully developed, it's virtually impossible to know the exact location that will get hit the hardest, and even harder to know the exact snow depth for any given location.

Those uncertainties can lead to 'flip-flopping'

Quite often we see a forecast model run for a storm that's a week away show a foot of snowfall for a location. Then 12 hours later, that same model is showing 3 to 5 inches of snow. Over the next few days, these model "flip-flops" can happen enough times to make a person dizzy.

That's why it's important to wait until models seem a little more consistent with what is going to unfold, before we start buying into the forecast.

Another wrinkle in this complicated process is that many of the maps you see on social media don't account for how much snow can be produced from the forecast amount of liquid equivalent precipitation.

WHAT?

Yes, this is known as the snow ratio. It's the difference in how light, fluffy snow can stack up higher than heavy, wet snow.

Also without knowing what type of frozen precipitation is expected, maps can look inflated. For example, if an area is expected to get sleet instead of snow, the snow totals will look higher on the maps.

There can also be differences depending on which forecast model

Take the two images below for example. They are snapshots of the exact same model run, just from two different models for snow that's expected across the Midwest.

Model 1 is much more conservative with the snow amounts and shows the heaviest snow across central Michigan and northern Indiana.

Model 2 shows a much more robust solution to the winter weather, and the location for snow is quite different.

Resisting the urge to spread the virus

The next time you come across a post on social media that looks to completely bury your town in a historic snowstorm (and you know it will happen), resist the urge to share the post.

Instead, consider the source. If the person who posted the image isn't a familiar face that you've seen on TV, or a trained meteorologist from the National Weather Service or a private forecast company such as weather.com, a quick Google search of their name will almost always tell you if this is a reputable source.

If the post is from a reputable source (like the one above), go ahead and share away! However, if the post is too far out than reasonable, and/or you have never heard of the person/source that has shared the information, it's best to just keep scrolling.

Know that just like all forecasts, snow forecasts are difficult, and unfortunately you might have to wait until just a few days before to get those fine details nailed.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.