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Weather Journal

with Kevin Myatt

Hail of a storm

Posted Sep28, 2006 at 04:05 PM

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A severe thunderstorm passed over the Roanoke Valley about 4 p.m., one of many that have occurred in the area today as a strong cold front pressed into warm, humid air. I watched this storm pass over the city and shot some photos, three of which are posted here. (Click here for bigger versions of the top photo , the middle photo, and the bottom photo).

There have been a number of reports of 3/4 to 1-inch hail in the Roanoke Valley with the passage of this storm. I'm also hearing reports of hail accumulated so deep in some parts of Botetourt County that it looks a light snowfall. Also some reports of trees blown down in the storm.

(Click here for a list of storm reports throughout Virginia.) Please email me with any reports or photos.

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I did observe considerable rotation in parts of this storm, though it appeared to be high-based and not a tornadic threat. Radar was showing a "mesocyclone," or broad low-level rotation with the storm as it passed over, which enhances hail and wind potential.

Below-freezing temperatures aloft helped hail to form in apparently prolific amounts with today's storms. Afternoon heating caused updrafts to carry moisture up beyond the freezing line, where it froze, and sometimes got carried up repeatedly, adding extra layers of ice until the hail was big enough that it fell to Earth.

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Strong downdrafts caused some gusty winds with the storms. Rotation, as was indicated by radar, would have kept updrafts and downdrafts separate, allowing the storm to grow and strengthen for a longer period of time than the short-lived "pulse" storms we see most of the time here in the mountains.

The severe thunderstorm watch issued for the area earlier this afternoon has expired, as the strong cold front that triggered these storms has pushed the activity farther east. You probably already feel the difference in temperatures outside, as things have cooled off considerably from earlier.

Severe weather will be replaced by much cooler fall-like weather for the weekend.

Comments

# 1

[September 29, 2006 8:32 AM]

Holly
I spent an hour and a half on 81 from the truck scales, where I saw what looked like snow on the ground to exit 141 at Rt. 419. Couldn't see any reason, except the weather. Great photos.
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Mug of Kevin Myatt

Kevin Myatt works on the copy desk for The Roanoke Times and is its principal weather geek, writing a weekly weather column and advising the newsroom on weather topics. He helps guide students on a storm chasing trip to the central U.S. each May and was an editor for "Hurricanes and the Middle Atlantic States."

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