The week ahead: Severe weather Saturday, but drier, cooler next week

While Saturday looks to be at least a partial washout, and severe weather threatens to derail Saturday night’s NASCAR race (sorry, race fans), there’s some good news. Once we’re done dealing with severe weather, we’ve got some incredible weather headed our way for next week. Are you ready for cooler temperatures and reduced humidity? I know I am.

September 7, 2012; 1:02 PM • by Weather Dan

I know, I know. It’s been a week now. A week of muggy days and humid nights, and only a few thunderstorms to break up the monotony. Meteorological summer is over, but the summer-like weather just hasn’t gotten the hint. Here’s the good news – you’re going to LOVE next week. The bad news? We’ve got to go through a little severe weather to get there.

I’d be remiss if I didn’t link to a Nate Silver article titled “The Weatherman is not a Moron” that appeared on the New York Times website this morning. If you’ve ever silently (or publicly) uttered negative words towards me or any other meteorologist, read this and get a picture about what really goes on in the world of weather forecasting, and just how far we’ve come in the last several decades.

The Week Ahead

If I had to pick a word to describe Friday, it would probably be “just short of oppressive.” (Oops, that’s not a word. Oh well.) There’s a much cooler Canadian airmass headed our way next week. The drawback is that we’ve got to deal with a particularly strong cold front this weekend, and when a strong lifting mechanism like a cold front interacts with a very moist, very warm airmass, we’ve got nearly ideal conditions for severe weather.

The Storm Prediction Center is highlighting eastern and central Virginia with a 15% risk for severe weather on Saturday. While we’re not under the gun for the worst of it, do not be surprised to see any outdoor plans, especially later in the day. Widespread showers and thunderstorms, some with hail larger than 1 inch in diameter or winds greater than 60 mph are possible through Saturday evening as the front makes its way across Virginia. At this point, I’d be surprised if Saturday night’s race at RIR makes it to completion without dealing with at least a little rain. Make sure you’re prepared in the event a severe thunderstorm decides to pass over or near the track.

This is the plot for temperatures at the 850 millibar pressure level (roughly 5,000 feet in altitude) for 11am Saturday. While temperatures are near 20C (68F) over Virginia, over the extreme northern Great Lakes, they’re closer to 5C (41F). While all that cold air won’t make it all the way to Virginia, we’ll still see about a 15-degree drop in temperatures aloft by Sunday morning. That translates from highs near 90 (like today) to highs closer to 75, which we’ll see by Sunday and Monday. And not only are temperatures set to fall, dewpoints are going to go from 70F (an indicator of near-tropical humidity levels) to 55-60F next week. You’ll notice a dramatic improvement compared to this week.

You can see the passing of the front on the temperature and dewpoint plots above, as temperatures begin to plummet Saturday evening. By the time most of the city wakes up Sunday morning, it’s going to be completely different. Enjoy the weather both on Sunday and next week – it’s going to be fantastic.

September 7, 2012 1:02 PM 0