Potsdam, NY, Dec 31, 1969 — Towering black clouds gave a dramatic warning of the storm sweeping toward Potsdam mid-afternoon Tuesday. Most alarming was a funnel-shaped cloud reported by eyewitnesses, and captured in photographs. Say "funnel" and lots of us think: "tornado."
But not all funnel clouds are tornadoes, even when they're apparently dropping down from a big, black cloud.
Martha Foley got an alternative explanation and another name, derecho, from Aileen O'Donogue, who teaches climatology as well as astronomy at St. Lawrence University. Aileen was on the ground watching as the storm came toward Potsdam. (Note: we'd love a high resolution picture of Tuesday's funnel-shaped cloud. E-mail images to: email@example.com)