(SOUTHERN COLORADO) — Forecasting can be an interesting business. Several times a day, more than half a dozen computer models process current weather data and run a suite of mathematical equations to make predictions about the future state of the atmosphere.

Most weather apps on your phone, or automated weather forecast sites, provide you with a forecast for the point on the earth you are interested in from one specific “run” of one of these models.

According to FOX21 Storm Team Chief Meteorologist Matt Meister, when making his forecast, he uses a combination of:

  • The current runs of all computer models
  • Previous runs of those same models
  • The knowledge he has about the known shortcomings of each of those models
  • The 3D model of the atmosphere that Matt pulls from his education and 25 years of Colorado forecasting experience
  • And, a detailed recollection of previous storms that have moved through our area

You’ll often hear Matt say that forecasting a storm in the future, is a process. As storms get closer and we get more information about them, forecasts will become more detailed with respect to timing, impacts, and specific parameters of the expected weather.

Here’s an example of what that process looks like from a week out to a storm’s arrival.

There are multiple pieces regarding the middle of next week, Feb. 14-16, that make a significant storm possible. These include the path the storm is likely to take from the Pacific Ocean toward Colorado, a path that will also allow it to draw in cold air from the Canadian plains.

Here’s a representative example as of Wednesday late morning, that shows the potential for a mature circulation approaching from the west, right along the Colorado/New Mexico line.

While the position ending up in this spot at this time is low, the pattern is right.

The image above is of the middle of the troposphere from the European model. The red arrows show the “divergent” air over Colorado ahead of the storm circulation. Divergent air in the mid-levels indicates rising vertical motion that would be present over the state. Rising air creates clouds and precipitation if adequate moisture is present.
The image above is of surface features, clouds, and precipitation from the European model for late Wednesday at the time of the mid-level features in the image above. As you can see from the blue (indicating snow) a major storm is forecast by this model at this time.

Given the mid-level and surface features presented in the images above, here is the snow accumulation forecast from the European model from Tuesday through Thursday (Feb. 14-16) of next week.

The image below shows the same mid-level forecast from the European model that we analyzed above, side-by-side with the same mid-level parameters for late Wednesday from the American computer model.

While at first glance, there seems to be a pretty major difference in the path, it is well observed that the American computer model has a northern bias on the forecasted path of storms.

Additionally, given the climatology of mature storms coming off the Atlantic Ocean into Europe as a persistent pattern of weather for the continent, the mathematics of the European model is tuned for handling these mature cyclones and helps to give us higher confidence in how it is handling the evolution of the storm.

Here’s Matt’s take: For me, at this point, sitting here one week out, the most significant concern I have is how low-level Gulf of Mexico moisture may or may not be able to be used by the storm.

There is a storm earlier in the week that will be passing too far to our south to do too much to Colorado’s weather, but you can see in the movie below of the European model’s surface dewpoint forecast, that there may not be enough time for low-level moisture to “return” behind the first storm.

There is still work to be done of course and we certainly will make tweaks that you’ll notice on air and in the FOX21 Weather App (Download it on Apple or Google Play) over the days ahead.

For now, the FOX21 Storm Team wanted to make you aware and give a window into the behind-the-scenes process!