below freezing air + 62 degree F lake water + upper level jet = SNOW!!!!
two feet of wet snow + leaves still on trees = you sitting in the dark
From the Rochester Democrat and Chronical:
(October 14, 2006) — Meteorologists say they are not surprised by criticism for not predicting the storm that dumped as much as 2 feet of snow Friday.
The National Weather Service staff had expected a "really big" lake effect event for a couple of days, but they weren't sure whether it would include mostly rain, mostly snow, or a mix, said meteorologist Tom Paone.
They concluded that Lake Erie's 62-degree waters would warm the cold Canadian air passing over enough to make rain, not snow, except for inland and some higher elevations.
At 10:15 a.m. Thursday, the National Weather Service forecast called for occasional lake effect rain showers mixed with sleet.
For Thursday night, the service predicted bands of lake effect sleet changing to wet snow at times, especially inland, with accumulations of an inch or two.
But a cold front moved in from Canada faster than expected while high-altitude jet stream winds lifted that air, cooling the atmosphere and triggering snow rather than rain.
"It was a very narrow threshold teetering between rain and snow, and the additional lift with the jet stream just pushed everything right over and caused everything to change over to snow," Paone said.
After the snow started Thursday afternoon, it cooled the air even more and reinforced the conditions driving the event.
It took Chuck Tingley, a meteorologist for the National Weather Service in Buffalo, 55 minutes to drive the 11.5 miles to work about 4:30 Friday morning.
"I had to go the long way around and take different streets, and I stopped to help a couple of people because their vehicles wouldn't make it."
Tingley said he and his colleagues have learned they can't be too thin-skinned in their business.
"We can be right, or nearly right, 19 out of 20 times. That one time we're not on the mark, that's the one people will remember," he said. "Fortunately it really doesn't happen that often."