Warm, dry and snow-scarce conditions in western US may waver soon
Pacific storms packing moisture, colder air, rain and snow are likely to return to the western United States during weeks two and three of February.
After weeks of warmth and dryness, a Pacific storm pattern shift brings rain back to the Pacific Northwest and snow to western mountains late this weekend and early next week.
A mainly dry, unseasonably warm setup that has persisted over much of the western United States for the past month or so is about to break down. While that pattern shift may not bring massive changes all at once, it could allow storms to return to California and bring opportunities for snow to the interior West in the coming weeks.
The jet stream has been convoluted over the past month. A large dip in the East has driven waves of Arctic air from Minnesota to Florida. In the West, the jet stream has had a large northward bulge, leading to a lack of storms, mainly dry and warm conditions and areas of air stagnation.
Beginning later this weekend, the jet stream will become a little less convoluted while maintaining the eastern dip and western bulge.
This subtle change will allow a storm from the northern Pacific to approach the northwestern U.S. with areas of rain and mountain snow from Washington to northern and western Oregon, northern Idaho and the northwestern parts of Montana and California.
Snow levels will dip down to pass level in the Washington Cascades late in the weekend to early next week, with slippery travel.
That storm will succeed in dragging colder air and snow into the zone from the interior Northwest to the northern part of the Rockies during the first part of next week.
Snow is much needed not only to support the region's skiing industry in the short term, but also to help with spring runoff and water-use concerns for the summer season. A lack of deep winter snow means that streams and rivers will run low sooner in the spring, unless there is ample thunderstorm activity.
"There are multiple locations in Florida that have received more snow this season than Salt Lake City," AccuWeather Meteorologist Brandon Buckingham said. "Valparaiso and Crestview, Florida, have picked up 0.3 of an inch of snow, while Milton, Florida, has received 0.5 of an inch. Meanwhile, Salt Lake City has picked up only 0.1 of an inch this winter, compared to a historical average to date of 33 inches."
The snow drought is far-reaching inland from the Cascades and Sierra Nevada in the West Coast states. Lander, Wyoming, has recorded only about 10% of its seasonal snowfall through Feb. 5. For the same period, Flagstaff, located high in the mountains of northern Arizona, has received only about one-quarter of its historical average.
Some of the moisture and energy from the upcoming storm in the Northwest early next week will go on to seed a vast zone of snow and ice over the north-central and northeastern regions of the U.S. later next week.
Another part of that storm and one that follows along the Pacific coast will tend to sink southward in the Western states next week with spotty areas of rain and mountain snow.
"Colder and more moist Pacific air will flow across much of the West during weeks two and three of February," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said. "A period of wet and snowy weather will return after a midwinter hiatus for much of the West."
The gradual moistening and cooling will take some time to unfold. For example, temperatures that surged into the 70s, 80s, and near 90 on Wednesday in coastal areas of Southern California will gradually trend downward into next week, with highs forecast to return to near the historical average by the middle of next week.
"There is some indication that a large storm will form and roll into California toward the middle of the month," AccuWeather Senior Long-Range Meteorologist Joe Lundberg said.
"If this storm lives up to speculation, it should bring decent snow to the mountains in the southwestern quarter of the nation," Lundberg added. "The amount of snow Salt Lake City might receive from it is uncertain this far out, but the Sierra Nevada should make up for some lost ground with practically no snow in the past five weeks."
The same storm could renew heavy rain and the risk of flash flooding in portions of California and the deserts.
As more potent storms begin to roll in from the Pacific, areas of persistent valley fog over the interior West will gradually disperse. However, there will still be at least several more days of dense fog and poor air quality for locations such as California's Central Valley.
Weather conditions look to be dry for the big game on Sunday in Santa Clara, California. The day may start with fog in some areas, however.
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