Strong winds knocked down power lines in Greece, N.Y., on Wednesday, March 8, 2017.(Photo: Carlos Ortiz, Rochester (N.Y.) Democrat and Chronicle)
ROCHESTER, N.Y. — For once, it was too sunny in Rochester, N.Y.
The devastating windstorm that struck the Rochester region Wednesday and left thousands without power was because of an unusual confluence of factors. The most unusual of those factors was the copious sunshine Wednesday, which helped make a windy day even windier.
If you want to blame anything for the storm, then, blame the sun.
At its peak, Wednesday's strong windstorm knocked out power to at least 140,000 customers in a six-county region. As of early Friday morning, about 104,000 customers remained without power. One utility, National Grid estimated that 90% of its customers should have power back by Friday evening. Rochester Gas & Electric couldn't say when power would be restored. In addition, some schools in the region would be closed for a second day.
Meteorologists said strong windstorms, of which Rochester has had two this March, are not unusual this time of year, when powerful low-pressure systems roam the continent. Most of the high-wind events in recent years have occurred in January, February or March.
Related:Windstorms leave thousands without power across USA
But one thing that made this one stand apart was the sheer power the system packed, and the extent of its wind field. When gales shrieked through Rochester on Wednesday afternoon, the low was 900 miles to the northwest — much farther away than is normally the case.
"It was a very, very strong storm and it ... covered a very large area," National Weather Service meteorologist Jim Mitchell said Thursday.
It also had an unusually strong current of air circulating around it at 3,000 to 4,000 feet above the surface, said Mitchell and fellow meteorologist Bob Hamilton. That low-level jet, as it's called, moving at 70 mph to 80 mph, wound up fueling the damaging winds on the ground.
That's where the sun comes in.
While approaching lows and associated cold fronts often generate clouds, rain or snow, this one did not. In part that's because the incoming air simply wasn't cold enough to create clouds or snow, Mitchell said.
The absence of clouds allowed the sun to heat the earth's surface. By the afternoon, that warmth was causing ground-level air to rise and create thermals — the updrafts on which hawks love to soar, Hamilton noted.
The thermals mixed with the fast-moving wind several thousand feet up, displacing that cooler air and causing the current to dive toward the surface, where it enhanced the winds already blowing there.
"Everything was set up perfectly — the wind direction, the timing of the afternoon sunshine — for us to be in the strongest winds," Mitchell said. "The main driver behind the wind was the sun. As soon as the sun went down, the strong wind shut right off."
Inevitably, some have already invoked global warming as an explanation for two powerful storms in just eight days' time. This part of the country has been unusually warm for more than a year, after all.
But Mitchell said he saw no evidence for the involvement of the planet's warming. Rather, he said western New York just happened to be in the way of a storm track that was moving robust low-pressure systems through this part of the continent at the moment.
"It’s just a matter of (weather) patterns, and patterns change," he said. "That’s not an atypical track for a storm."
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