Ask A Met: Are Forecasts Better On The Coasts?

This week's question comes from Morning Brief reader Emily who asks, "I've always heard that forecasts are more reliable on the coasts than in the middle of the country. Is that true?"

Meteorologist Jonathan Belles: I'll rate this partially true and, over time, it's becoming less true.

If you're on the East Coast, your forecast is going to be slightly more reliable than the middle of the country and on the West Coast. The reason for that is that it's how we collect data.

If you're on the West Coast, essentially all of your weather comes from the ocean. We have no ground observing sites over the Pacific Ocean. We have buoys and that sort of thing, but really quite little data is being collected at the surface of the ocean before weather arrives on the West Coast.

The East Coast weather systems, on the other hand, are largely coming across the continent. They have to go through all of those observing sites. They have to go through the twice-a-day weather balloon launches that we put up. Think about every airport, every local bank has their own observing station that brings in temperature, dew point, wind speed, sun conditions, and anything else you could think of, and all of that goes into the forecasts.

We just have this plethora of data that we get before storms arrive on the East Coast, and all of that data not only goes into short-term forecasts, but it also goes into long-term forecasts. The longer systems linger over the middle of the country, the better the forecast is going to be by the time the systems get to the East Coast.

The caveat that I have with this explanation is that we have very high-resolution satellites now.

If you had talked to Ben Franklin back in 1776 and had to make some forecasts, he would have basically gone out and gotten the telegrams and other mail from places like Chicago or Houston to see what sort of storm systems would be moving in.

There are two reasons that weather is a little bit more volatile or unpredictable in the middle of the country. The first is that ocean weather doesn't change as quickly, because water temperatures are slow to change.

Air temperature will change based on whatever it's in contact with and land changes much faster than the ocean surface temperature.

In the Plains and parts of the Midwest where it's relatively flat, there's less friction to break up weather systems. So, storm systems can come down the Plains and there's nothing to stop them from rapidly changing conditions.

There are sites across the northern and central Plains where you get 50-plus degree temperature changes in a day. It's often the magnitude of those changes that are difficult to forecast. We may forecast a 70 degree change and it might end up being 80 degrees or something like that.

The hardest thing for us to forecast is generally a record. Particularly those big changes, because we as humans want to recognize the weather that we're forecasting. We try not to forecast the absurd weather, the outliers, the record breakers.

Obviously, if models start indicating that a record will be broken, we're going to forecast it. But, in general, we are going to have an inherent tendency to avoid it.