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Our temperatures have been up and down lately, and that's because of the position of the jet stream. Last week we were under the influence of an upper level low. So what is an upper level low? It's an area of low pressure in the upper atmosphere that is associated with a jet stream trough. A trough, or dip, in the jet stream usually brings us cool weather. The opposite of a trough is a ridge, and that typically brings us warm weather. Our weather last week featured sunny mornings, cloudy afternoons, and unseasonably cool temperatures. An upper level low was stuck to our north over eastern Canada, and the upper level pattern finally changed to a more zonal flow this week. Zonal means the jet stream is generally flowing from west to east with no troughs or ridges. While in zonal flow, disturbances move through more quickly. Anyways, the reason we had clouds building in during the afternoon hours is because there was a cold pool of air above us. The sun (strong this time of year) was shining during the morning and heating up the earth's surface. That warm air rose and met up with the cooler air above us and formed clouds. Some pop up showers and even thundershowers are possible in that type of pattern as well. Then at night, when we lost the heating from the sun, the clouds dissipated. Upper level lows can certainly make for a difficult forecast because a day might seem sunny, but the clouds building in the afternoon can bust a temperature forecast. Also, the shower and thunderstorm activity can be very isolated. While home in PA last weekend, I overheard a conversation of people complaining about how the weatherman was wrong and they didn't see a drop of rain. What people don't realize is we're not just forecasting for one specific area. When I say there is a chance of isolated storms, it's just that: isolated. Our viewing area is spread over a few counties, so if a storm occurs somewhere within that area, I feel I've done my job. And on my way home to PA last Friday, I went through a terrible storm, so the weatherman at home was indeed right. (And the viewing area up there is HUGE!)
Below is a map of upper level wind flow. It's easy to see the trough... look for the area where the lines curve down into a U shape.
And now on to your racing forecasts:
IndyCar Series - Richmond International Raceway, Saturday (6/28) at 8 p.m. ET on ESPN. Since I will be at the race in person (yay!), I will paying extra close attention to this forecast! Southerly flow around an area of high pressure will provide hot and humid conditions Friday into Saturday. Friday will be partly cloudy and hot with highs reaching into the mid 90's. Qualifying is Friday at 7:30 p.m., and the temperature will be warm near 90 degrees. There is a slight chance of a shower or thunderstorm due to daytime heating and instability. Saturday will be partly cloudy and hot again with temperatures in the lower 90's. The race time temperature will be near 89 degrees. A slow moving cold front will start approaching from the west, and a few thunderstorms are possible ahead of the front.
NASCAR Craftsman Truck Series - Memphis Motorsports Park, Saturday (6/28) at 8:30 p.m. ET on SPEED. It will be warm and humid in Tennessee on Saturday with temperatures climbing into the lower 90's. Expect a mix of sun and clouds with a chance of an afternoon or evening thunderstorm. At race time, the temperature will be slightly better near 85 degrees.
NASCAR Nationwide Series - New Hampshire International Speedway, Saturday (6/28) at 2:30 p.m. ET RIGHT HERE ON TV3! An upper level low pressure system will make its way toward New Hampshire through the weekend along with a frontal boundary. It looks like Saturday will be mostly cloudy with a chance of showers and thunderstorms. The temperature at race time will be near 77 degrees.
NASCAR Sprint Cup - New Hampshire International Speedway, Sunday (6/29) at 12:30 p.m. ET on TNT. A frontal boundary that passes through on Friday will meander back into the region on Sunday. Unfortunately, it has the potential to produce clouds and scattered showers. Due to cloud cover, the temperatures will be in the 70's. The temperature at race time will be around 74. Qualifying is on Friday, however, and southerly flow ahead of the cold front will bring warm temperatures. Skies will be partly sunny, and the temperature will be in the mid 80's. There is a chance some storms could develop Friday afternoon.
Winchester Speedway - Saturday (6/28), gates open at 4:30 p.m., racing starts at 7 p.m., and there is a meet and greet with Rodney Combs at 5:30 p.m. It will be warm and humid in the Shenandoah Valley on Saturday. The high temperature will be near 89 degrees. A slow moving cold front moving in from the west may contribute to the development of afternoon and evening thunderstorms. The temperature at race time will be near 85 degrees.
Here are two pictures from Richmond last year.
Lynn, Theresa, and Andrea with Gene Simmons at the IndyCar fan club gathering.
Lynn with Darren Manning at the autograph session. Not sure what that face is, haha!
Send me your racing or weather pictures! cassie@tv3winchester.com And be sure to listen to Sirius Spedway on Sirius Satellite Radio channel 128 to hear me do the NASCAR forecast live every Thursday around 3:30 p.m.!
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