Storms rolling through the Mid-Atlantic

After a relatively cool summer, hot humid conditions have prevailed in the Mid-Atlantic and Northeast of the U.S. in the past week. Today, in particular, featured hot, humid conditions, providing fuel for storms. A system passed over the region, providing the necessary lift to get these storms going. The result was a long line of storms moving through Maryland, producing heavy rain, lightning, and damaging winds. Multiple people shared their view of the storm, both during and after, which is displayed on this map showing their corresponding location for each picture.

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Overlay of pictures on map of MD. Times vary.

The two pictures in western MD were taken following the passage of the storm. The radar image below roughly corresponds to times of these pictures. You can see a north-south oriented line of reds, indicating heavy rain, that had just passed through.

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Radar image from 4:46 EDT, showing line of storms passing through Washington County, MD

Let’s take a closer look at the pictures from this time. While the overall sky remained covered in cloud, a key feature in both of these photos are the lower level clouds hanging beneath. These are referred to as fractus and form in the moist environment that remains after the rain has passed.

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Photo courtesy of Nancy Kirkpatrick in Cascade, MD (2 Sept 2014, after storm passed) showing fractus clouds.

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Photo after the storm passed showing lower residual clouds in Smithsburg, MD (Debbie Rowe, 2 Sept 2014)

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Another view from Debbie Rowe of the back edge of the storm.

This line of storm continued its path across Maryland throughout the evening. The radar image below shows that hours later, it maintained a linear structure on the other side of the state. Also notice storms developing over northern VA at this time; a focus for the next picture.

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Radar image from 6:43 EDT

This new cluster of storms, forming in a similar environment as the earlier round, later went on to also organize into a linear structure. In this later radar image, you can see this structure, the reds indicating heavy rain, and a line of lighter blues out ahead. This latter feature is what we call an outflow boundary, and indicates strong, cold winds moving out ahead of the storm, lifting up warm, moist air ahead of it along with any dust, insects, etc. in its path. (Check out our previous post to learn more about this outflow.)

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Radar image from 7:27 EDT. White arrow shows location of outflow boundary.

Notice at this time, the leading edge of this storm is moving over Washington, D.C. Jen Horneman was driving just outside the city at this time and snapped this photo out the window (the third picture in the map above). A close-up view reveals a much lower cloud base as the warm moist air being lifted along the outflow cools and condenses to form this menacing, low cloud. Strong winds were expected with this feature, followed by heavy rain.

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Photo courtesy of Jen Horneman near Arlington, VA

After these storms moved through, in addition to the heavy rain indicated by the oranges and reds in the radar image, damaging winds were associated with these storms. Many reports indicated large trees down throughout the state.

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Severe weather reports from the Storm Prediction Center. Blues indicate severe winds.

Were you affected by these storms? Feel free to share with us any pictures or stories you may have!

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