The process and importance of in-depth winter forecasts

With the potential of snow in the forecast this weekend, you may have noticed graphics circulating on the internet or weather apps that are producing significant and alarming numbers. This hype often comes with the unrealistic outcomes models produce in the long-range forecast. These long-range models, like the GFS or ECMWF, give a good idea of the larger-scale pattern, but are not as efficient at forecasting the specifics that are needed to produce an accurate forecast. This is why meteorologists have a specific method when it comes to winter weather forecasting that ensures accuracy without creating extra concern or panic.

This method starts around a week before the event occurs. Meteorologists use long-range models to forecast the development of storms or systems. Specific numbers have not been consulted yet; this is just an indication of potential days to keep an eye on or to communicate that there could be activity without spreading any potential false information.

Once 3 to 5 days out is reached, more agreement amongst models is starting to be observed. Medium and long-range models are consulted during this portion of the forecasting process, which starts to focus a bit more on the smaller-scale features and differences in the area. Numbers still aren't taken to be the truth, but they are consulted in order to see which area will most likely receive the largest impacts.

1 to 2 days out is when the details are fine-tuned, and totals begin to be communicated with the impacts those totals may bring. Long, medium, and short-range models are all consulted to find the most consistent outcomes, as the higher resolution with shorter-range models allows for specifics to be ironed out. This allows meteorologists to provide the most accurate information daily to keep you prepared.

For the forecast this weekend, we are currently in the 3 to 5 day range of the forecasting process. The system that is expected has been monitored, and the team has been watching how the models have been handling the evolution of this system. We are starting to understand that areas that are most likely to pick up on meaningful snow totals will be along and south of I-70, but we are also aware that dangerously cold weather is also expected to take over the region. The team is confident in the dangerous wind chills, which is why ABC 17 Stormtrack Weather Alert Days have been issued for that period of time, but we are still watching where accumulating snow will occur.

There are a few words we use to help viewers understand the thinking on an event. "Potential" means that signals have been seen, but action doesn't quite need to be taken yet. "Disagreement" means that the models are fighting, so there is lots of uncertainty with the forecast. "Impactful" means that there is higher confidence in high hazards occurring that you need to be aware of. "Historic" would be a word that isn't used often, so when it is, listen and take the proper measures to prepare.

In any event, there are a couple of rules to follow to avoid panic. First, avoid the hype social media that is posting the worst possible outcome over a week out. Second, don't post model snapshots over 300 hours out, as these are also extremely inaccurate and can cause unnecessary worry about an event. Third, avoid specific numbers until reaching the final 24-48 hours before an event. Finally, make sure to share any potential changes, caveats, and potential scenarios so that preparations can be made as needed.