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More thunderstorms possible Wednesday and Thursday afternoons

Tuesday afternoon my backyard rain gauge recorded 1.6 inches of rain from the fierce tropical downpours that occurred as a severe thunderstorm blasted through the area.  We also experienced thunderstorms (and another 0.2 inches of rain in my gauge) during the passage of a mesoscale convective system early this morning as a warm front lifted through the Fredericksburg area.  And now the Storm Prediction Center is forecasting at least a chance of severe storms the next two afternoons, the result of a cold frontal push through the Mid-Atlantic coupled with the upper level conditions created by the long-standing “cutoff low” that is still spinning over the Midwest.

Take a look at this map of surface conditions at 8:45 a.m. today (Wednesday):

Note the very long purple boundary arcing from the tip of Lake Michigan up into Canada and then down to the northern tip of Virginia.  This is an occluded front, an area where a surface cold front has caught up with a warm front and forced the warm air upwards off the surface and creating widespread showers and storms.  Occluded fronts aren’t unusual, but this is one of the longest occlusions I can remember.   Also, note the cold front (blue line with jagged teeth) perched way up in western Canada.  This is the leading edge of the cool autumn air that will provide our weekend cool down after that same front plows through here sometime later this week.

In summary, keep an eye on the sky this afternoon and pay attention to media alerts to possible severe weather to include even more potential for flash flooding.  Autumn weather is coming, but we have to get through the next couple of stormy days first.

Permalink: http://news.fredericksburg.com/weather/2011/09/28/more-thunderstorms-possible-wednesday-and-thursday-afternoons/

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