Cold weather brings snow and false forecasts: validating long range forecasting

Weather

As winter looms on the horizon, it’s almost time to start forecasting snow totals. And now more than ever, you need a winter weather forecast source you can trust. With the recent spread of volatile weather model forecasting, it can be hard to know what forecast to count on.

When browsing social media pay close attention to who is posting forecasts and what specifically they are forecasting. With the rise and expansion of social media, a lot more people use those platforms as a news and weather source (Silva et al. 2014).

In case you haven’t heard, there is a slim chance we could see snow as early as Sunday. But these chances remain low and the likelihood of any accumulation of snow is nearly non-existent as the ground temperatures are too warm to allow accumulations. That being said, seeing snowfall this early in the season is not unheard of or impossible.

A few things to note when it comes to long range forecasting.

1) Because weather models are a mathematical simulation as time goes on error grows exponentially with time. In other words, the Butterfly Effect Theory. The models perform much better on the next 2 to 3 days. They can wildly fluctuate and give shocking (and highly unlikely) snow forecasts in the 5 to 10 day period. These are the maps that get major attention on social media.

2) Precipitation accumulation over the course of multiple days will be larger. We’ve seen Weather Prediction Center (WPC) 7 days rain outlooks to show multiple inches of rain to fall. This is over the course of a few days where absorption, evaporation, and melting occurs and will lessen the standing total of precipitation currently on the ground.

3) Models are not an exact science, hence why “meteorologists get to keep their job and be wrong 50% of the time”. As a matter of fact our forecasts are quite accurate and have been getting better as time goes on. Myself and other forecasters validate our forecasts to improve how we forecast. Plus having a good understanding of the dynamics of the atmosphere helps see when models show bias or inaccuracies so forecasts can be more accurate, especially during severe weather.

There are tons of wonderful sources to see weather models and forecasts from sites like:
National Weather Service
NWS Quad Cities
OurQuadCities Weather
SPC HREF Model
Pivotal Weather
College of Dupage Weather
The list can go on and on, but all these sites can give you the same general information.

The key thing to know is how these models work and why they put out the information that they do, which was mentioned earlier.

A good idea if you like to look at models, is to pay attention to how they change over time. If multiple models and different runs are showing similar results for the same time frame this can show higher confidence to what might actually happen. At the same time models can also be all over the place, much like this upcoming Sunday. These are a few model outputs of the Global Forecasting System (GFS) over the past 3 days and the latest output from the European Center for Medium-range Weather Forecasting (ECMWF).

Each of these model outputs are very different, meaning the snowfall confidence is very low, granted that doesn’t mean snow is out of the question.

There are a few things you can do to stop the spread of false forecasts and outlandish claims, by looking at a few things. Check with your Local 4 pinpoint meteorologists either on TV or our friends at the local National Weather Service office. We have an office here in Davenport by the Mount Joy airport. Are they talking about 4-8 inches of snow on Sunday, or “deadly cold”?

Facebook pages and personal accounts sometimes over-hype forecasts by spreading fear for attention and clicks. These types of pages can make professional forecasters jobs harder as they have to prove it’s inaccuracies. A good example of a Facebook page to avoid is called “Meteorologists”. This site is notorious for spreading long range model forecasts as truth.

The claim for “Deadly Cold” on October 18th is false, our forecasts show a high and low for 48ºF and 42ºF. The NWS office in Fargo, ND has a high and low on the 18th as 39ºF and 23ºF (as of 2:32PM Oct. 13th).

When sharing weather forecasts, or other information for that matter, be sure to check who is sharing that information. Are they credible, a known meteorologist, or associated with a credible organization such as the NWS, AccuWeather, The Weather Channel, or a local TV Meteorologists. Still be mindful of bias with those sources.

For forecasts question or other meteorological questions you can always reach out to meteorologists on social media or email!
Twitter:
Andy McCray
Zane Satre
Garrett Heyd

Facebook:
Andy McCray
Zane Satre
Garrett Heyd




References

NWS Fargo
The Butterfly Effect Theory American Scientist
The Butterfly Effect Theory Forbes
Forecast Accuracy
5 Myths About Weather Forecasting
The Weatherman is not a Moron

Ripberger, J. T., H. C. Jenkins-Smith, C. L.
Silva, D. E. Carlson, and M.
Henderson, 2014: Social Media and
Severe Weather: Do Tweets Provide
a Valid Indicator of Public Attention
to Severe Weather Risk
Communication? Weather, Climate,
and Society, 6, 520–530,
doi:10.1175/wcas-d-13-00028.1.

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