What happened to the storm forecast?
That’s what HANRadio personality Rob Adams asked Jacob Meisel of swctweather.com on the web radio station’s stormcast Tuesday morning. Essentially, Mr. Meisel said, forecasters relied too heavily on one weather model when they predicted a blizzard of “historic” proportions. The storm’s behavior was also difficult to track.
“What happened is that our most accurate model predicted the historic blizzard,” he said, adding it was “accurate on run after run.” He was referring to the European weather model, which tends to be very accurate in the winter, he said. But there were “a lot of other models,” not quite as accurate, that predicted lower snowfall totals.
Mr. Meisel, who offers a weather forecasting subscription service, said he looked at those other models but added “it’s hard to forecast six to 12 [inches] when the National Weather Service is predicting two to three feet.”
At 9 p.m. Monday night, he said, one model was predicting four to 35 inches for New York City, depending on small shifts of 20 to 30 miles. Those last-minute shifts, he said, put the worst bands of snow over New London and New Haven counties instead of farther west.
“I have never seen a span like this on a weather model,” he said. The short-range weather models used for fine-tuning a storm when it is 12 to 18 hours away, were showing widely varying ranges of snowfall.
Most of New England received snowfall near predicted amounts, he said, “except for the sharp cutoff at the western edge.
“Our weather models were not consistent and there was no consistent way to see this final scenario. The storm’s quick formation off shore was hard for the models to pick up.”
On Monday, a “standard Alberta clipper” moved down through the continental U.S., the type of storm that usually would bring a quick one to four inches of snow.
“This one dove far enough south to pick up energy from the jet stream and transfer it to a secondary low off shore,” Mr. Meisel said. “Weather models are notorious for being poor at handling the transfer of energy between the original low pressure center and the one offshore the energy is being transferred to. When that happens, you are at risk for something going wrong with your storm. Those are the storms where you have the massive changes in forecast.”
In this case, he said, the energy transfer took too long, the storm formed a little too far east, the storm didn’t properly get captured in the upper atmosphere and then it turned back west and spun out to sea, cutting down totals on the western edge.
“We were probably an hour and a half away from the energy transfer for the storm to clobber southwest Connecticut,” he said.
His only criticism was that forecasters did not emphasize the proper level of confidence — or lack of confidence — their predictions carried.
Looking to the short-term future, Mr. Meisel said we could see an Alberta clipper swinging through Thursday to Friday bringing one to three inches of snow. A storm Sunday into Monday could bring anywhere from three to six or four to eight inches, he said, but he did not have a lot of confidence in that prediction since the storm is far enough away things could change.
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