What’s the best weather model?: Ensemble versus regular

In the vast network of different weather models that meteorologists work with, there can be some confusion in the terminology and the differences between model A and model B - Let's discuss ensembles

When looking to put together a forecasts, meteorologists have a vast toolbox of resources to choose from. Knowing which tools to use for which situations is key in forecasting.

You wouldn’t want to use a screwdriver to hammer in a nail right? I mean, you can try, but it will likely lead to some major frustrations down the line when you find out a hammer would be much easier.

Let’s talk about one specific tool of forecast – ensembles.

Picture 1

  • This is a singular model run – a single solution that shows a possible scenario involving precipitation for our upcoming system early next week.
  • Notice the intricate green, pink, and light blue markings on the map showing a detailed map of expected precipitation.
  • These detailed maps are favored because they are… well… detailed. It shows intricate details that gives the viewer a presentation of expected conditions. But is the map accurate?

Picture 2

  • If you’re looking at storm systems in the distant future – it’s better to stick with ensembles.
  • Ensembles take a singular model run and run it several times, (sometimes hundreds of times), changing little parameters such as water content or pressure to simulate as many scenarios as possible.
  • The ensemble then combines all those models runs into one product – the one you see above.
  • This is a less detailed map, so it’s not as useful if you’re looking for specific information like specific snow totals or timing of a storm system – but it can give a general idea of where models are converging for certain categories like overall snow depth.
  • In this map, it clearly shows a favored area along the South Dakota/Nebraska State line for snowfall from Monday into Tuesday – So this will give meteorologists more confidence than a single model run that is pictured in the figure 1.

Be careful when sharing snow maps online that are several days out – As most of those models will be single model runs. When 3 or more days out, ensembles should be widely used for forecasting rather than one stop solutions.

By Friday, we’ll likely be able to switch from ensembles to single model runs, as meteorologists will have higher confidence in more detailed maps with better data coming in.

Categories: Weather Daily