On a roll in Amherst
On Tuesday, a line of very active weather developed on the leading edge of a cold front travelling across New Brunswick and western P.E.I. Hail was reported at the base of many of the more powerful storm cells. After the storms had passed, it looked like it had snowed near Alberton, P.E.I.
The next day I received an email and that great photo from Darrell Cole. He said the cloud appeared at about 9 p.m.; there were several bolts of lightning off in the distance, but no rain.
He wanted to know if this cloud was a shelf cloud.
Not quite, Darrell, but the two are commonly confused. A roll cloud is a relatively rare, lowlevel horizontal, tube-shaped “accessory cloud” completely detached from the cumulonimbus cloud or thunderstorm base.
You’ll find it along the leading edge of a line of thunderstorms or along a cold front with a very strong temperature inversion; that was certainly the case Tuesday afternoon. Depending on the conditions, a roll cloud can last for several hours.
People often say that the cylindrical cloud looks like a tornado on its side; while that’s a good observation, roll clouds are not and do not produce tornadoes.
Keep an eye on the sky and stay safe.