Monday, May 17, 2010

What caused rapid storm intensification over Memphis on the evening of May 16, 2010?

On the evening of May 16, 2010, a mesoscale convective system (MCS) moved into the Mid-South from the west. The quasi-linear complex of thunderstorms, followed by an area of rain, reached the metro area around 7pm. As it approached, the strongest storms were a bowing segment of thunderstorms south of the city over northwest Mississippi and strong/severe storms well north, with a relative dearth of strong storms directly west of the bridge. It appeared the city would miss the strongest activity.

As evidenced by the StormView Radar loop shown below, while no severe storms struck the city, there was a definite "explosion" of heavier precipitation along a north-south line (basically right along the Midtown stretch of I-240 north into Shelby Forest) just after the outflow boundary ahead of the area of precipitation reached the city. The very heavy precipitation didn't continue across Shelby County, but preceded several miles before weakening again (after the time of this loop).

So what caused the sudden explosion of precipitation intensities? Could it have been an urban heat island effect, which could have easily provided extra convective potential? Perhaps another atmospheric boundary of some sort existed across that region? These types of systems are certainly not steady-state either, so it could have been a natural progression of the convective system. I didn't get a good chance to examine the data in real-time; I'll take a closer look and let you know if I find anything. In any case, it made for an interesting radar loop worth sharing.



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1 comment:

Wintermute said...

Maybe what blew my empty dumpster over.

That owly bar seems to be what made the captcha image red-x.