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Beyond The Forecast: Temperature, precipitation type and this week’s winter storm

Portion of our area under winter storm watch on Wednesday

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Happy Monday! The talk of the town this week is our upcoming winter storm. A good portion of our viewing area has already been placed under a winter storm watch on Wednesday. We have a pretty good handle on how we think things will go with this system in our daily forecast article, written by Your Local Weather Authority meteorologist Chris Michaels. I’m going to use this space to explain why it’s a difficult forecast.

This probably goes without saying, but the number one factor in forecasting winter storms is temperature. We have to look at temperatures at the surface and aloft, which we have the ability to do via weather balloons and other instruments. Most weather models provide a “sounding” of expected temperature profiles for events like this.

The easiest events to forecast for are the ones where temperatures are either above or below freezing throughout the entire atmosphere, from cloud to ground. The expected precipitation type in these storms is easy to decipher, either rain (above freezing) or snow (below freezing).

What makes storms like this week’s difficult to forecast for is when you have cold air and warmer air battling it out at the surface and aloft. You may have heard a meteorologist say the dreaded “warm nose” term when talking about mixed-bag precipitation events.

At this time, we expect our furthest northern areas to have the coldest air in place Wednesday, which is good news for snow lovers there. The odds of a mixed bag go up as you travel south. Some in our area may not get any snow at all; it may just be freezing rain and rain for them.

There’s also a chance you may start with snow, switch to freezing rain or rain, then switch back to snow at some point.

We’ll be fine-tuning our forecast through Tuesday, then bringing you the latest conditions during the storm on Wednesday. Please stay tuned for updates!

You can always get specific forecast details for your zone, whether it’s the Roanoke Valley, New River Valley, Southside or elsewhere around Southwest and Central Virginia, anytime at WSLS.com/weather. Know your zone!

In case you missed it, we’re posting great weather and science content on WSLS.com. Here are a few links from the past week to check out:

If you prefer your weather information delivered by social media, you can follow Your Local Weather Authority on Facebook and Twitter.

-- Justin McKee


About the Author:

Justin McKee presents the weather forecast on 10 News Saturday and Sunday mornings from 6 to 8 a.m. He also fills in for other meteorologists during the week.