Before the first flake hits the ground, winter storm forecasts can trigger days of anticipation and sometimes unnecessary alarm.
As this weekend’s anticipated snow totals climb and wintry predictions spread far in advance, ranging from a few inches of snow to well over a foot, along with potentially icy conditions from Texas to New England, UVA Today spoke with Christine Hall, an assistant professor in the Department of Natural Sciences at the University of Virginia’s College at Wise, about why big storms tend to become big news long before they arrive.
Christine Hall, an assistant professor at the University of Virginia’s College at Wise who teaches meteorology courses, says the best thing to do right now is watch the forecast and use common sense when making weekend plans. (Contributed photo)
Q. With a possible winter storm in the forecast this weekend, what’s the most important thing people should understand right now about what we know – and don’t know?
A. The main thing to understand is that, while weather forecast accuracy continues to improve with new technology, weather predictions can still have inaccuracies, especially when we are trying to predict what will happen several days in the future.
That’s not to say that forecasts aren’t useful, but it is important to take them with a grain of salt, especially with regard to things like exact numbers of how much snow to expect. This also doesn’t mean that meteorologists don’t know what they are doing or that they are “just guessing”!
There are just so many different things that go into developing a forecast, and they are changing even as you are putting the forecast together, so it is hard to get it completely right 100% of the time, even with all of the technology available today.
Q. What changes between a seven-day forecast and a 48-hour forecast?
A. In the time it takes to get from a seven-day forecast to a 48-hour forecast, the weather system that we are watching has gotten much closer, and there is less variation in predictions of where it will be and what the conditions will be like. Basically, as we get closer in time, we are better able to narrow down what the possibilities are for the next day or so.
Q. What are the biggest sources of uncertainty in winter storm forecasts, especially when it comes to snow versus rain or ice?
A. Precipitation is already trickier to forecast than something like temperature because there are more variables that can keep changing. Snowfall amounts are even trickier, with a number of extra factors like when or whether it will start sticking, how fluffy versus wet it will be, and snow having a tendency to fall in bands, meaning that even neighboring towns might get different amounts based on how the storm happens to move through.
