Cold fronts tonight and later Tuesday before end-of-week warming and drying
Monday, February 27, 2017
A deep trough of low pressure along the West Coast will move eastward across the Great Basin today, with several pieces of the storm bringing snows to the Steamboat Springs area starting this this afternoon or evening. The first part of the storm brings breezy southwest flow to our area today, with the best upward forcing staying north and south of us.
However, a cool front does pass through the area this evening, backing mountain-top winds slightly to the west and limiting accumulations as the Steamboat Ski Area is most favored with northwest flow. I would expect the best snows from this first part of the storm to be associated with this front Monday evening, leaving 1-4” of snow for the Tuesday morning report.
While we may see some snow showers for the first half of Tuesday, trailing energy from the Pacific Northwest brings a stronger cold front through northern Colorado later Tuesday, backing the winds to the northwest and bringing light to moderate snows for a time.
Amounts may be limited by decreasing moisture just as the winds turn to our favorable northwest direction, but we should see around 3-6” by a very cold Wednesday morning.
Showers will decrease for a time Wednesday before picking up again later in the day as a final wave in northwest flow brings another push of cold air and upward forcing. Again, moisture is sparse so I would expect 1-4” for the Thursday morning report.
At this point, a dry wave is forecast to move north of our area early on Friday before much warmer and drier weather is advertised to invade our area later in the day. The weekend forecast is uncertain , but generally unexciting as weak waves in westerly flow may suppress the driest air to our south and could bring clouds to northern Colorado.
Snows wait until Thursday and Friday
Wednesday, February 22, 2017
I’d like to post a quick update as the storm is not evolving as previously forecast. Some cool air did sneak in here during the day, but the best precipitation from the leading edge of the storm ended up north of the Steamboat Springs area along the further-north-than-forecast position of the frontal boundary.
So the 4-8” I originally forecast for Thursday morning won’t happen as the front looks to remain north of our area for most of the overnight hours. Snows will have to wait until the main storm approaches the area around report time. I would now expect only and inch or two for the Thursday morning report, with snows increasing during the early morning hours and becoming moderate to heavy at times as the main cold front passes through.
Snows will continue in the cold, moist and unstable northwest flow behind the front through Friday night, and I’m hopeful we’ll see 4-8” of snow for the Friday morning report and another 4-8” for the Saturday morning report.
There may be a brief break in snows Saturday morning before a drier and weaker storm again brings snow showers to the Steamboat Springs area Saturday afternoon and overnight.
Winter returns starting Wednesday
Monday, February 20, 2017
A storm off the West Coast is again pounding the California mountains, and energy ejecting out ahead of the storm will help form a southwest to northeast oriented front across the Great Basin. This front will bring clouds and the possibility of light showers to the Steamboat Springs area on Tuesday ahead of new storm cycle that that will persist into the weekend.
The front is forecast to move through northern Colorado early Wednesday, bringing cooler temperatures and a likely burst of heavy snow down to the Yampa Valley floor. Light to moderate snows should continue during the day and overnight as the front stalls near our region and subtle, hard-to-resolve waves of energy periodically enhance snowfall rates.
Snowfall forecast amounts are bolstered by atmospheric cooling, but tempered by the predominantly west-southwest mountain-top winds and the location of the upper level jet stream just north of the Colorado border. Right now, I expect 4-8” of snow by Thursday morning.
Meanwhile, additional energy from the northern latitudes kicks the West Coast storm inland later Wednesday across the Great Basin, and another push of significantly colder air with moderate to heavy snows is expected sometime on Thursday. Good snow should follow the front as the upper level jet stream pushes south of northern Colorado and maintains the large-scale upward motion that is conducive to precipitation.
Light to moderate snows will continue overnight Thursday and through much of Friday as cool, moist and unstable northwest flow lingers behind the departing storm. If the storm comes together as advertised by some models, we could see as much as 6-12” by Friday morning and an additional 3-6” during the day.
Additional energy and cold air from the northern latitudes travels down the east side of a building Bering Sea ridge into the Gulf of Alaska, forming a new storm and reinforcing a generally west-to-east frontal boundary across the Great Basin. Models disagree on how much energy loiters off the West Coast vs. how much moves inland and the amount of ridging ahead of the storm, but unsettled conditions with seasonably cool temperatures are expected for the weekend.
Some models have the storm off the West Coast drawing in subtropical moisture and setting the stage for another atmospheric river event. Though the timing is uncertain, models have additional northern latitude energy again dropping into the Gulf of Alaska, displacing the hopefully very moist storm westward early in the work week and bringing another round of likely significant precipitation to the area.
Unsettled week ahead with a Sunday night storm and a long-duration event starting mid-week
Friday, February 17, 2017
A storm from the central Pacific that is currently inundating California will split as it crosses the West Coast on Saturday. Some energy ejecting out ahead of the storm will bring the chance of light showers to the Steamboat Springs area tonight and again later Saturday, but the bulk of the storm will stay south of our area.
A trailing wave of energy strengthens the northern part of the split later Sunday and brings some cool air and the best chance of accumulating snowfall through Monday morning. Due to the split flow and additional upstream energy, the snowfall forecast for Monday morning is uncertain, but at this point I would expect 4-8” for the President’s Day report as there is some cool, moist and unstable northwest flow for a time.
Unsettled weather will persist after a brief clearing later Monday behind the cool front as waves in the relatively warm Pacific airmass move over the area on Tuesday and early Wednesday.
Meanwhile, a central Pacific ridge builds somewhere around the Bering Sea and the Gulf of Alaska, similar to patterns observed earlier in this winter season. Cold air from Siberia and the North Pole is forecast to slide southward along the east side of this ridge and begin a likely long-duration winter storm event starting later Wednesday and lasting into the weekend.
The specifics are highly uncertain as some of the cold air is forecast to move southwestward underneath the eastern Pacific ridge and merge with the branch of the Pacific jet stream that undercuts this ridge. If this pattern evolves similar to the pattern observed earlier in the season, which seems likely, then significant snows are possible as the moist Pacific jet stream once again battles the cold air from the northern latitudes over the western states. Current long-term forecasts have March arriving like a lion as this active period looks to last through at least the first week of March.
Active weather returns after a beautiful work week
Monday, February 13, 2017
The disappearance of the Bering Sea ridge has allowed cold air from Siberia and the North Pole to surge into the central Pacific and re-energize the jet stream. A ridge of high pressure that has built off the West Coast in response to the strong Pacific jet stream will translate over the western U.S. during the work week, bringing warm and mostly sunny conditions through Thursday.
Starting around Friday, energy from the Pacific jet will force the ridge of high pressure eastward and bring showers to the western U.S. There are a number of waves of energy that will move through the area for the long President’s Day weekend, and the forecast timing, strength and duration of the precipitation will almost certainly change as we get closer to the weekend. Hopefully, better model agreement and more details will emerge for my late-week forecast.
Right now, the first wave is forecast to move over the Continental Divide on Friday, bringing mostly light snow showers to the Steamboat Springs area during the day.
Another Pacific wave splits as it crosses the West Coast on Saturday, and this may bring some more showers to the area mid-weekend if the parts of the storm are close enough to Colorado.
A third wave quickly follows the second, and this may bring a better chance of snows to the Steamboat Springs area around Monday before a brief break is advertised ahead of another stormy period that is forecast to close out the month.