Storms crossing the warm front in North Dakota on May 8, 2005

What happened

Thunderstorms formed north of Fargo, ND on May 8, 2005. As the storms moved northward, they got enhanced by convergence and maybe enhanced low-level flow (i.e. helicity) when they crossed the warm front. While there were no reports of them, if these storms were to be tornadic, this would be the optimum time. The storms crossed the warm front between about 22Z (western storms) and about 23Z (eastern storms). Dewpoints at the time were in the 10 to 12°C range--not too impressive. Had there been more moisture present, tornadoes would have been more likely. As it is, though, watch the shape of the strongest storm at 22:04Z. It shows that supercell kidney bean shape, although the storm-relative velocities didn't show any rotation. The largest hail reported from these storms was the size of golf balls--about 40 mm in diameter.

Storm reports can be found here

RADAR images

Base reflectivity tilt 1

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