Thursday, November 16, 2017
A strong winter-like storm off the West Coast has brought over a foot of snow to the Sierra’s so far. More is coming for them today and tonight as the storm travels across the Great Basin on Friday, bringing first rain and then snow to the Steamboat Springs area starting early Friday morning.
The storm is comprised of cold air from the northern latitudes and much warmer and wetter air from the southern latitudes. Technically, the cold air results from a wave moving southwestward in the polar jet stream to the north while the warm and moist air results from the northeastward oriented subtropical jet stream to the south. As the storm moves across the Great Basin, rain showers will start in the early morning hours with snow showers at the higher elevations along with windy conditions.
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Showers will increase and become locally heavy as a strong cold front approaches during the afternoon hours. For those keeping score, the European ECMWF model has been the most consistent forecasting the afternoon or early evening arrival of the cold front. Rain will change to snow in the Yampa Valley and strong winds will veer from the southwest or west to the northwest as quite cold air moves over the area. Travel will become difficult for a time later Friday as moderate to heavy snow causes accumulations on the roadways and blowing snow limits visibility.
The snow will turn showery in the drier but still unstable northwest flow behind the front, ending sometime Saturday morning. We should see some sun by later in the day, though temperatures will stay cold. I would expect 8-16” of snow at the higher elevations and several inches on the Yampa Valley floor.
Drier air and warmer temperatures grace most of the west Sunday for a beautiful day after a chilly start.
Another Pacific Northwest storm approaches the coast on Monday and splits, with the resultant southern part of the storm traveling over Steamboat Springs on Tuesday. There is uncertainty with respect to how much energy and moisture is partitioned between the split storms, but snow showers are currently advertised for late Monday into early Tuesday.
Showers will end later Tuesday and temperatures will begin warming as a ridge of high pressure builds over the western states. However, moisture moving through the ridge will keep some clouds for Wednesday, Steamboat’s anticipated Opening Day, and Thanksgiving Day.
Longer-range models agree that another storm that moves across the Gulf of Alaska will impact our area around Friday or Saturday. The European ECMWF has the storm splitting, with the southern part of the storm forming a closed low and moving over our area Saturday. The American GFS keeps the storm more consolidated, bringing it across the area on Friday. Both models bring precipitation, however both have not been consistent with the late week predictions, leading to a fair bit of uncertainty regarding the forecast.