When my phone app says snow -- what's really happening?

Don Schwenneker Image
Tuesday, December 13, 2022
FILE PHOTO (From a snow forecast in November 2018)

RALEIGH, N.C. (WTVD) -- I walked into several emails today asking "Why aren't you talking about the next week?!" I even got an email from a viewer with a picture of their forecast from their phone. It's low resolution but it does show the snowflakes on Friday morning in Sanford.

As a matter of fact, all of the messages I got from viewers said "that's what my phone says!" Ahhhh, the phone forecast ...

Let's talk about that for a moment. Here's a truth about most phone forecasts, they are never looked at by a human. Most weather apps take a computer model (usually only one of many) that updates 3, 6, or 12 hours.

The app then generates a forecast and pushes it out to your phone. And because it generates one with every model calculation, it will change. A forecast may show snow in the morning, then later, on the same day when the model updates, show sun for the VERY SAME DAY!

It's because the model changed. My guess is (and it's just my opinion) that the apps take the worst of the models and use them to make a forecast.

By showing you bad weather, the app gets you to click on it. Here's an example of what I'm talking about. Let's look at two different versions (we call them runs) of the same models and what they are saying.

First, this is what the model showed when it came out Sunday afternoon.

You can see LOTS of purple right in the heart of NC. That would mean a wintry mix of snow, sleet, and rain. That's why the viewer's app showed the snowflakes on Friday. Now let's look at the EXACT SAME MODEL 24 hours later and see what it says

It does show snow, but mainly at the beach. Plus, it's completely precipitation-free for Lee County. I would bet my viewer's phone is showing sunshine on Friday!

So which model do I believe? Well, I tend to look at a lot of models (including those called "ensembles") and blend them together using my experience in forecasting, to make my own forecast. I wish there was an all-knowing APP, but there just isn't. At least, not yet. The 7-day forecast we post every day here is made by a human and not changed every three hours. And trust me, when there's snow in the forecast, we will let you know!

My friend, Brad Panovich, is a meteorologist over in Charlotte. He compares long-range forecasts to a game of golf.

When you first hit the ball, you're just trying to get it in the fairway. Then as you get closer to the green, you're narrowing the ball's target down to a tiny hole.

Same with long-range forecasting. When we look seven days out, we are just looking to see if it's clear, or if it's going to rain/snow by day 7. Then as we get closer, we narrow it down to what type of precipitation we'll see, and where it will hit. It takes time to develop a good winter forecast and the entire ABC11 weather team works hard at it every day.

For 7-10 days from now, I'm just trying to hit the fairway. Anyone who tells you they know it will snow in 10 days in NC is just trying to get your click...