Big storm forecast for weekend

A winter storm that could bring between 12 to 18 inches of snow to the higher elevations of the Sierra is forecast to hit the Eastern Sierra this weekend, with the first storm coming in Friday and into Saturday and another, lighter storm forecast for Saturday evening and into Sunday.

The two storms will bring an abrupt and cold change to the warm spring weather that has so far characterized April, as a cold front drops down from the Gulf of Alaska and combines with a strong moisture plume coming in from the Pacific Ocean off the coast of California near Paso Robles.

“This looks to be a good storm,” said Howard Sheckter, Mammoth’s amateur weather forecaster.

“Earlier this week, the models split the trough, but now, the full wave is coming in and it is aimed more at the Central and Southern Sierra, not the Northern Sierra.”

The storms should add another foot to a foot and a half to the Sierra crest, with lesser amounts below that, he said.

“We should get about six inches in town.”

The National Weather Service concurs.

“Quite a bit of instability should lead to moderate to heavy precipitation in the Sierra,” according to the weather service.

“Models are still hinting at about a n inch of liquid (an inch of water can be very roughly translated to about a foot of snow, give or take several inches) along the Sierra crest. Snow levels will fall below 7,000 feet and may drop to near 5,000 feet Friday night and early Saturday morning.

“(The) main concern is potential for several inches of snow accumulation over the Sierra passes with light accumulations likely down to 5,500-6,000 feet.”

After the weekend, warm and dry weather should return as another high-pressure ridge builds up off the coast again, according to the weather service.

The dry spell could end in May, however. According to Sheckter, some climate forecast models are predicting more moisture, maybe as much as another inch or more.

There is also growing chatter among meteorologists about the building El Niño pattern in the Pacific Ocean; a pattern characterized by warming of ocean waters in certain parts of the Pacific. Currently, ocean temperatures are climbing fast and some forecasters are pointing toward the current developing El Niño as one of the strongest in many years.

The pattern, should it persist, could help to make the spring in the Eastern Sierra a wetter than average one, he said.

“With an El Niño, spring can linger into June,” he said.

Sheckter said he hopes the forecasters who are talking about a big El Niño year are right, since a strong El Niño pattern has been linked to big winters in the Eastern Sierra (although there are exceptions where the winters have also been average or dry).

He said he isn’t quite as aggressive about the chances of the strong El Niño pattern translating to a wet winter as some.

“Yes, it could be a humdinger, but what remains to be seen is if the Pacific Decadal Ossilation flips again back to negative,” Scheckter said. This particular weather pattern recently flipped to the postitive, but it has been in the negative phase for many years, and when it is in the negative phase, it tends to lessen the strength of the El Niño pattern.

If it flips back to negative, Sheckter said he believes the chances of this year’s El Niño producing a big winter for the Eastern Sierra are reduced.

“That’s the big question,” he said.