“What happened to the storm forecast?”
That’s what HAN Radio personality Rob Adams asked Jacob Meissel of swctweather.com on the web radio station’s stormcast Tuesday morning.
Essentially, Meissel said in response, 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,” said Meissel, 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.
Meissel, 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 2 to 3 feet.”
Meissel was interviewed by Adams and his HAN Radio Stormcast co-host John Kovach during the six hours of live coverage carried on Hersam Acorn’s local news websites in Connecticut and Lewisboro, N.Y., including SheltonHerald.com.
Last-minute shifts for storm
At 9 p.m. on Monday night, Meissel said, one model was predicting 4 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, Meissel 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.”
How the storm evolved
On Monday, a “standard Alberta clipper” moved down through the continental United States, the type of storm that usually would bring a quick 1 to 4 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,” Meissel said. “Weather models are notorious for being poor at handling the transfer of energy between the original low pressure center and the one offshore [that] the energy is being transferred to.
“When that happens, you are at risk for something going wrong with your storm,” he said. “ Those are the storms where you have the massive changes in forecast.”
Close … but no cigar
In this case, Meissel 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.
Meissel’s only criticism was that forecasters did not emphasize the proper level of confidence — or lack of confidence — their predictions carried.
The next storm systems
Looking to the short-term future, Meissel said we could see an Alberta clipper swinging through Thursday to Friday, bringing 1 to 3 inches of snow.
A storm Sunday into Monday could bring anywhere from 3 to 8 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.
You can listen to HAN Radio at hanradio.com or SheltonHerald.com. A program schedule appears on the home page of SheltonHerald.com.
Jeannette Ross is editor of The Wilton Bulletin, another Hersam Acorn newspaper and website.