Monday, July 19, 2010

Dwindling Rain Chances & More 100's Coming

Today should be the last day with decent rain chances in central Virginia this week. Scattered showers and storms will be possible in the area, mainly this afternoon and early evening, as an upper wave in the atmosphere tracks over the mid-Atlantic. Although our severe threat is very low (the higher risk is to Virginia's northeast), some of our storms could produce gusty winds for localized wind damage. Any of these storms will be capable of brief heavy downpours and lightning. Rain chances Tuesday and Wednesday are lower, but because of the heat and humidity, a few showers and storms are possible both afternoons. After that, though, we should be in for several days with highs around 100 degrees in central Virginia as a strong ridge expands over the Commonwealth. This is the same ridge that produced high heat in the southern Plains and parts of the Mississippi valley region last week into the weekend. As Aaron mentioned in a previous blog entry over the weekend, it doesn't appear that our warmer-than-normal temperatures will be going away anytime soon. Here is the latest three month temperature outlook for the U.S.:
Unfortunately, the precipitation outlook for Virginia isn't optimistic:
The most effective way for us to make up our precipitation deficit (about 5.5" inches below average year-to-date in Richmond right now) into the Fall would be for one or two tropical systems or their remnants to move over Virginia and dump widespread heavy rainfall. The downside of that, though, is flash flooding and potential wind damage and tornadoes that accompany tropical systems making landfall. It's a Catch-22, really. Nevertheless, the short-term drought is not likely to continue long-term, especially if we keep getting these showers and storms that produce locally heavy rainfall. Here's the Drought Outlook through October, which shows improvement for our moderate drought areas in the Commonwealth:

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