Saturday, July 21, 2007

The week ahead, plus a bit of history!

This blog post will have two parts. The first part will focus on this week's weather pattern across most of North America. It is an interesting set-up and I will explain what it means for us, especially come later next week into the weekend. Then, I will take you back to this weekend last year. If you thought this past week was rainy, wait until you hear the rain amounts we got last year!

This image tells some, but not all of the story. High pressure to our west will bring us seasonable temperatures for the first half of the week. Meanwhile, on the back side of the high, heat will be building big time, with triple digits all the way to the Canadian border! What this map doesn't show is an upper-level low that will be hanging around the mid-Atlantic and Northeast. This will not only bring scattered thunderstorms, possibly severe with hail, but it will also clog up the flow of weather systems. Usually, systems travel west to east. However, this low will dig in an be very stubborn, forcing the high pressure, and the heat, north into Canada. This will allow the hot airmass to become very strong. Eventually, the low will lose out and be broken down and the heat will come spilling east. This will probably happen later this week, and when it does, we will bake!

July 21st and July 22nd, 2006: A frontal boundary was stalled across the region, with cool air to the north and hot, humid air to the south. We were stuck in the middle of these air masses, right in the battle zone. As low pressure systems moved along this boundary, thunderstorms broke out and "trained" across the region. "Training" is when repeated thunderstorms move over the same area, over and over again. This usually results in excessive rainfall, as was the case last year. On the 21st, thunderstorms rumbled through Groton for most of the pre-dawn hours. These storms dumped 1.14" of rain. Then, the next morning, the same thing happened, but with more numerous and stronger storms. As a result, the 24-hour rain record for Groton (according to my rain stats, which I have been keeping since 2004) was crushed by noon. Those storms dumped 3.31", with another 0.04" coming later in the day. As a result, our two-day rainfall was a whopping 4.49"! By comparison, our four-day rain total this week (Tuesday-Friday) was 1.38".

Have a nice weekend everyone!

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