By Ron Smiley

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PITTSBURGH (KDKA) — Winter storm watches, and warnings have been issued across Western Pennsylvania, but there’s still a chance that the incoming winter weather system changes tracks.

As forecasters have been saying all along, even if the system track changes by 50 miles, it can mean the difference between several inches of snow.

KDKA Meteorologist Ron Smiley says it’s a tricky forecast, and one that could even bust.

Here’s his explanation of how weather forecasters look at at storm:

So anytime when there is a system like this you have to at some point sit back and ask, “what is the chance that this system goes bust?”

I wish I could give you a solid answer saying that I know beyond a doubt that this system will do what we are saying it is going to do; four inches or more of snow in Pittsburgh with a round of freezing rain. Sadly enough we cannot say for certain that this is going to happen. In fact going through all model data we see some models still showing little to no snow with this system.

When we forecast we look at probabilities. We try to find the sweet middle spot and assume that this is what most people will see. Normally most data, even with little agreement, will group into a middle range. There are always outliers though. Take a look at this map to see where data says that there is a 90 percent chance that we will see MORE snow than the number on the map.
Notice it’s near zero in Pittsburgh right now. That tells us that when it comes to how much snow we can guarantee our confidence is pretty low. I wish it was higher, that all data is pointing to those big snow totals but it is not.

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Another thing not pointing to big snow totals of over 4 inches is history. We are now able to also look at the current setup and have computers look at the top 10 events with a similar set-up and how they turned out. We do this in order to compare outcomes. This also shows a high bust chance with most of the area below a 30 percent chance for 4+ inches of snow.

So what does this tell me? It tells me that I should be looking and siding with the low range snow totals for this event. You never want to go into a storm with low confidence that what you are saying will happen. Sometimes though you have to play the cards you are dealt. So to answer the question there is a VERY good chance we see a busted forecast with this. History tells us that this atmospheric set-up rarely produces snow of more than 4” here locally. And there is model data, while an outlier that shows totals will be lower. If you’re not a fan of snow and cold you can hope for the best, but you should still prepare for the worst. There’s a flip side to this, when it comes to data at least, that shows much higher totals as well. I am good with our current forecast and think it is responsible.

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