Thursday, February 2, 2017
A very complicated weather pattern has developed off the West Coast as the Bering Sea ridge, which was observed earlier in the season, directs cold air from Siberia and western Canada into the Gulf of Alaska as Pacific energy is routed underneath. The end result will be a week of snowfall, with 3-6” of new snow for the Friday morning report, 1-4” for each of the weekend morning reports and likely significant accumulations for a couple of days next week.
Some of the cold air from Siberia and western Canada has mixed with a strong storm between Hawaii and the U.S. mainland and is bringing more heavy precipitation to the Sierra Nevada coastal mountain range. Some energy has ejected out ahead of this storm and has mixed with more cool air from western Canada, bringing the currently observed snowfall to the Steamboat Springs area. Short-range models have increased snowfall from this system, bringing moderate to sometimes heavy showers from this afternoon through the evening before tapering off around midnight and leaving 3-6” for the Friday morning report.
Additional energy and cold air dropping into the Gulf of Alaska on Friday will not only force this weakening storm eastward across the Great Basin, affecting our area Friday night into Saturday, but form a new and stronger storm off the West Coast as it phases with a separate storm undercutting the Bering Sea ridge.
The Friday-Saturday storm is a bit of a wild-card due to its weakening nature, but 1-4” are possible overnight Friday for the Saturday morning report with another 1-4” during the day, to be reported on the Sunday morning report.
Sunday looks to be precipitation-free but likely not cloud-free as moisture lingers in the still moist westerly flow.
Pacific energy undercutting the Bering Sea ridge is forecast to strengthen early in the work week and carry the new storm eastward. Waves of energy in the Pacific jet will interact with cool air moving southward from western Canada, likely bringing a long-duration snow event to Colorado starting later Monday.
Right now, models have the heaviest snows Monday night and again during the day Wednesday, with significant accumulations likely during each period, though the details are almost certain to change as we get closer to next week. Nicer weather is advertised to return near the end of the work week as a West Coast ridge translates over the area.
Monday, January 30, 2017
A ridge of high pressure that has brought warming temperatures and sunny skies to the Steamboat Springs area will flatten over the next few days as northern Pacific energy combines with energy rotating around a developing Hudson Bay vortex. Winds will continue to increase on Tuesday, mixing and warming the low-elevation airmass and weakening or breaking the temperature inversion.
Moisture associated with the Pacific energy looks to bring clouds to the area later Tuesday with light snow showers possible overnight and into Wednesday, though the American GFS model is more bullish on that idea than the European ECMWF model.
A transient ridge will quickly pass over the area on Thursday, bringing some sun and warming the temperatures from Wednesday.
A very complicated pattern then develops off the West Coast as the Bering Sea ridge, which was observed earlier in the season, rebuilds and directs cold air from Siberia and western Canada into the Gulf of Alaska as Pacific energy is routed underneath. Some of this cold air will mix with a strong storm between Hawaii and the U.S. mainland before the storm begins affecting the West Coast by early Thursday.
Some energy is ejected out ahead of this storm and combines with some cool air from western Canada, again bringing the possibility of light snow showers to our area for Thursday night into Friday morning.
Unsurprisingly with such a complicated pattern, there is model disagreement about the strength of the Pacific storm as it crosses the West Coast on Friday, travels across the Great Basin overnight and brings snow to northern Colorado on Saturday. The more bullish American GFS indicates snowfall amounts in the 4-8” range by the Sunday morning report while the European ECMWF is quite a bit drier.
Pacific energy is forecast to continue to impinge upon the West Coast after the weekend, and we may get some sort of storm through the area early in the next work week, but model disagreement over the weekend decreases confidence in the details of that storm.
Thursday, January 26, 2017
The last impulse of energy from this storm is currently moving southward from Wyoming and will keep light snow showers over Mt. Werner overnight and possibly into Friday morning, leaving under an inch or two of light fluffy snow for the morning report in continued cold temperatures.
Behind the storm, the sun returns as a ridge of high pressure builds and moves eastward from the West Coast, bringing warming temperatures to the mountain slopes by Saturday afternoon. The Steamboat Springs valley will be slower to warm, as strong surface cooling at night will form temperature inversions that will be reinforced by the warming aloft.
Sunday looks to be similar to Saturday, but warmer, before northern Pacific energy rides over the top of the ridge and flattens it on Monday, bringing some wind that will help mix the low-elevation airmass. This mixing will bring the warmer temperatures aloft downwards, warming the valley temperatures and weakening or breaking the temperature inversion.
Moisture associated with the Pacific energy may be close enough to bring clouds to the area later Tuesday with a stray shower possible overnight and into Wednesday, though the American GFS is more bullish on that idea than the European ECMWF.
The American GFS also brings some Pacific energy over the central California coast on Wednesday and advertises showers over our area on Thursday, though the European ECMWF is again less optimistic.
The long-range forecast has both models building a ridge over the Bering Sea by around the following weekend which was the active and favorable weather pattern that was present over our area starting in early December. A ridge in this position sets up a battle between airmasses as Pacific energy undercutting the ridge eventually interacts with cold air from the northern latitudes which is forced south along the east side of the ridge.
Sunday, January 22, 2017
A large and powerful storm currently located off the Pacific Northwest coast is pounding the California mountains with heavy precipitation and will bring snow showers to the Continental Divide this evening. The main part of the storm will arrive early Monday, likely just after report time, so I expect 1-4”of snow on the Monday morning report.
But snows should increase in the morning with breezy to windy southwest winds. Snow amounts are always difficult to forecast under these conditions as the heaviest snowfall often occurs in bands, and model disagreement is making the forecast even tougher.
Coincidentally, a closed low forms in southern Idaho and travels north of the Steamboat Springs area later in the day Monday and overnight, and the exact path of this closed low will also affect snow amounts. A cold front associated with this closed low also passes through our area Monday evening, increasing snowfall rates and bringing the cold air that will be with us for the rest of the work week.
There is model disagreement with respect to how far north this closed low forms, and some solutions have good snow overnight and through Tuesday, while others keep Steamboat Springs drier as precipitation occurs north and south of us.
At this point, I would side with the more optimistic model forecast as we do have good cooling and unstable and moist northwest flow behind the front, similar to but stronger than the just-passed storm that left 9” at mid-mountain and a foot up top. I hope to see 6-12” of snow on the Tuesday morning report, with the first part of that likely being wind affected during the day Monday followed by colder and fluffier snow after the cold front passes.
Tuesday is another tough forecast day due to substantial model disagreement, but again I like the more aggressive solution which could bring another 5-10” of very light and fluffy low-density snow during the day Tuesday and overnight, which will be reported on Wednesday morning.
Additional energy moving southward keeps still fluffy snow going for Wednesday into Thursday, with another 3-6” expected on the Thursday morning report.
Another lobe of energy may pass over our area later Thursday into Friday morning, so light snow showers might not completely end before Friday afternoon.
It does look like this cold and snowy week will be followed by a building West Coast ridge which should bring warmer and drier weather at some point this weekend, at least for the mountain slopes as temperature inversions will keep the valleys cool after any cloud-free nights.
Thursday, January 19, 2017
A weakening Pacific storm will move over the Steamboat Springs area in pieces tonight and Friday. Snow showers should begin around mid-evening and persist overnight and most of tomorrow. I would expect 1-3” on the Friday morning report, and even though showers should intensify in the morning as the flow briefly veers to the northwest, I would expect only another 1-3” during the day which will be reported on the Saturday morning report.
A stronger and colder second storm crosses the West Coast on Friday and splits, with the southern piece traveling southeastward through the Great Basin on Saturday. There may be a break in precipitation over our area from Friday night through Saturday morning, and even though the bulk of this storm will stay to our west and southwest, snow showers are likely from Saturday through Sunday afternoons. I think we will do a little better from this second storm as the temperatures are cooler and the northwest flow behind the front is stronger, and I expect 2-4” for the Sunday morning report and another 1-3” during the day.
Meanwhile another strong wave in the energetic Pacific jet stream phases with the remaining northern piece of the second storm in the Gulf of Alaska and forms the strongest storm of the three. The storm will begin affecting the West Coast later Saturday before it crosses the coast overnight and brings snow showers to the Continental Divide as early as Sunday night.
Breezy to windy southwest flow will increase by Monday morning as temperatures begin to cool, and moderate to heavy showers are expected during the day Monday. Snow amounts are always difficult to forecast under these conditions as the heaviest snowfall often occurs in bands, but significant accumulations are possible in this warm sector of the storm.
By Monday evening, more Pacific Northwest energy drops into the back of the storm and causes it to split, with the northern part of the split forming a closed circulation over southern Wyoming and the southern portion traveling south towards Baja.
A strong cold front associated with this closed circulation will move over the Steamboat Springs area later Monday, veering mountain-top winds to our favorable northwest direction and bringing a period moderate to heavy snows that will last overnight and through the first part of Tuesday before decreasing in intensity by late in the day. I would expect significant accumulations by the Tuesday morning report, with amounts dependent upon the evolution of the closed circulation.
Though snows will decrease, snow showers will likely not end until late in the work week as the Baja part of this storm loiters to our southwest and encourages additional waves of cold and moist air to move southward from the Northwest and western Canada. As a result, I would expect new snow to be reported Wednesday and Thursday mornings as well.
It does look like this cold and snowy week will be followed by a building West Coast ridge which should bring warmer and drier weather heading into the following weekend.