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.
Monday, January 16, 2017
The pesky upper low responsible for the valley clouds these past two days has split, with the northern piece of the spit traveling east of the Steamboat Springs area tonight. While the southern piece will remain south of our area as it affects the southern third of the country over the coming work week, the sun will finally make an appearance over the Yampa Valley for the next several days.
A wave in the very strong Pacific jet stream will cross the West Coast around Wednesday night and spread clouds over our area later Thursday. This wave will weaken as it crosses the Great Basin, bringing only light snow showers to Mt. Werner on Friday and Friday night.
A stronger storm approaches the Pacific Northwest coast on Friday and splits, with the southern piece traveling southeastward through the Great Basin on Saturday. At this time, models have the bulk of this second storm staying to our west and southwest, and light snow showers are expected from Saturday through Sunday afternoons.
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 on Sunday before it crosses the coast later that day and first brings mid and high level clouds to our area on Monday and snow showers starting around Monday evening.
While this last storm will likely last the longest and bring the most accumulating snows, the details will have to wait until there is better model agreement - hopefully by next Thursday or Friday in time for my next forecast.
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.