Snow may be a no-show
Forecasters aren’t giving up on late snow, but others say weather is likely to stay mild through spring
La Niña was supposed to bring lots of snow this winter, just like it did three of the past four winter seasons.
Inland Northwest residents were prepared for the worst based on previous experiences with La Niña since 2007.
But so far, the region has seen less than half its normal snow and less than a quarter of what fell through Jan. 2 a year ago.
“The whole West Coast is pretty dry,” said Jon Fox, forecaster with the National Weather Service in Spokane.
“There are many more things in play than La Niña,” Fox said of the phenomenon in which the waters in the equatorial Pacific are colder than normal.
At least three other patterns can influence winter weather, including a positive Arctic Oscillation, which is an air pressure pattern in which polar air stays near the top of the earth rather than spilling southward. That has been the case in recent weeks.
So far, Spokane International Airport has had only 9 inches of snow, compared with 23.1 inches in a normal season, through Jan. 2.
During the same period a year ago, Spokane had 43.3 inches.
The average for an entire season is 46.2 inches, based on climate data from 1981 through 2010.
December was unusually dry and snow-free, with only 2.4 inches of snow, compared with the average of 14.9 inches for the month.
Storms during November and again last week have provided the bulk of precipitation, which has been less than 60 percent of normal at 3.47 inches.
Ski areas have been operating on a strong base layer from a series of snow storms before Thanksgiving.
The snowpack is about 75 percent of normal in northeast Washington and parts of North Idaho.
The far northern Panhandle in Idaho has a snowpack that is 94 percent of normal. The Washington Cascades also have snowpack in excess of 90 percent of normal.
To the south, the mountains in Oregon are well below normal for snow at just over 40 percent.
The U.S. Climate Prediction Center has maintained its outlook for above-normal precipitation and below-normal temperatures through spring in the Pacific Northwest, largely because of the continuing presence of La Niña.
“They are not giving up on it yet,” Fox said.
In fact, the center’s preseason prediction called for a late onset to winter storms in this region. But Fox and other forecasters in Spokane are doubtful that La Niña is going to bring it on during the second half of winter.
Weather records show that when precipitation is well below normal in the first half of the winter, there is a 66 percent chance it is going to stay relatively dry through spring.
In only four years has a dry start turned around to bring above-normal precipitation, Fox said.
This season, the trend has been for storms to move north around a strong area of high pressure over the Northwest and near-shore waters.
The high has blunted and weakened storms as they move inland. Parts of the Columbia Basin have seen less than half their normal precipitation due to a persistent rain shadow caused by the Cascades.
“We expect this pattern to continue for the next seven days,” said Ellie Kelch, forecaster for the weather service in Spokane.
The U.S. Drought Monitor has placed the Inland Northwest in the abnormally dry category, the lowest level of drought.
At the start of the season, it was believed that La Niña’s influence would push the storm track north toward Alaska before plunging south along the coast with plenty of cold air and precipitation. That was the pattern in recent snowy winters.
In 2007-’08, 2008-’09 and 2010-’11, La Niña brought heavy snow, including record amounts.
Spokane had 23.3 inches of snow in 33 hours Dec. 17 and 18, 2008, which was the most in a two-day period. A 24-hour period at the heart of the storm set a record with 19.4 inches.
By the end of the season, the city reached an all-time season record for snowfall with 97.8 inches.