Archive for October 4, 2008

SUNSHINE, WARM AFTERNOONS, COOL NIGHTS MAKE FOR A GREAT WEEKEND… WHEN WILL THE STRING OF SUNNY DAYS END?… THE TROPICS ARE QUIET AS THE SEASON SLOWLY WINDS DOWN

I’ve seen this type of pattern many times during the month of October, where high pressure dominates and you can’t find any precipitation for hundreds of miles in any direction from Hampton Roads. This weekend will be fantastic and there is nearly a zero percent chance of rain. Why are quiet weather patterns like these so common in October? Well, there are several reasons and some are a bit complex, but the major reasons are 1) the ingredients for thunderstorms that are present throughout the summer are not there anymore as the sun’s angle has decreased and the length of the day is shortening rapidly. This takes heat and atmospheric instability out ot the equation for the most part. 2) the positioning of highs and lows makes for a lowering of humidity levels as our winds are not usually blowing from the south as they do during the summer months. They tend to blow offshore more often in October which means drier air 3) the jet stream has not made its return yet from the north so extra-tropical storms are not dominating the weather maps across North America. Those are just some of the reasons. Now, in a few short weeks, storminess will increase across the continent as cold air invasions begin to become more frequent and intense. It won’t be long before strong winds begin to blow and we see rapid changes in the weather due to extra-tropical cyclones moving across the nation as well as strong frontal systems and high pressure areas. So, enjoy this perfect “chamber of commerce” weather which will be perfect for many outdoor activities. I’m sure the folks that work outside all year who sweat during the summer and freeze during the winter love this time of year. Only the weather enthusiasts will find something to complain about during this relatively quiet time of year. What about the week ahead? A back door cold front will move through around Tuesday and will swing our winds to the NE. High pressure will build into Eastern Canada and New England later in the week. Now, sometimes during the fall, when highs build to our north and norheast, low pressure areas spin up to our south and east. Remember the nor’easter in September? Well, I’m not saying that this will happen and I haven’t seen this predicted anywhere. But, it’s something to think about late in the week. The tropics are quiet for now. Note that October sometimes has a secondary minor peak in activity, so it’s not over yet. However, tropical storms become less frequent on average with every passing day. The season officially ends on November 30th.

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