Wednesday, January 11, 2017
Another wave in the Pineapple Express phases with cool air traveling southward from western Canada and moves over the Steamboat Springs area this afternoon. Some dry air has unexpectedly worked in behind a weak wave last night, delaying the moderate to heavy snow showers until cooler temperatures arrive later today. Furthermore, the cooler air won’t be as cool as earlier forecast, further decreasing the originally forecast snowfall for overnight. The end result is I now expect a much lower 4-8” on the Thursday morning report.
Meanwhile, a splitting weather system crosses the West Coast on Thursday. Most of the energy forms a closed low that waffles off the coast of southern California through Saturday, with southwesterly flow ahead of the storm warming our temperatures during the day Thursday. Waves of energy in the northern part of the split will periodically enhance snowfall through Saturday morning as they pass near our area.
Right now, models indicate the best snow to occur from Thursday afternoon through Friday morning. Snow total will be dependent on the evolution of this closed low and the poorly resolved waves in the northern portion of the split, but another 4-8” of dense snow is possible by Friday morning. Snows should taper off during Friday before ending by Saturday morning, leaving another 1-4” of snow for the Saturday morning report.
While dry air lurks to our north through the weekend, the closed low off the southern California is forecast to slowly move northeast across the southern Great Basin on Sunday and Monday, keeping at least clouds over the area. Keeping in mind these closed lows are notoriously difficult to predict due to nebulous upper air forcing, dry air is expected to finally reach northern Colorado around Tuesday.
There are model differences with the next storm as the persistent Bering Sea ridge migrates to East Asia and allows cold air from Siberia to pour into the Pacific and energize the jet stream. But models generally have another surge of Pacific moisture moving over our area by later Wednesday or Thursday that brings precipitation back to our region.