Friday, January 31, 2014
Two waves in the Pacific branch of the polar jet stream stayed further south than I expected yesterday, with the first wave overnight yesterday giving big snows to Winter Park and Loveland, and the second wave during the day yesterday and overnight last night giving big snows to the rest of the I70 corridor and the Aspen areas. Clearly disappointing for us, and in hindsight, I should have placed greater emphasis on both the fact that Steamboat tends not to do well with predominantly westerly flow and models consistently had the best energy just to our south.
Furthermore, the wave for today also will affect the areas south of us the most so only light snow is expected this afternoon and tonight. However, a another arctic wave rotating around the persistent Hudson Bay vortex will begin cooling temperatures tonight and turn the flow to the northwest keeping light snowfall going through most of Saturday. This snow should of much lighter density as the heavy riming that occurred in yesterdays storm will be absent. I would expect 1-4” both on the Saturday and Sunday morning report, with most if not all of the snow in the Sunday morning report occurring before midnight Saturday.
Sunday should be a nice day with a cold start and the sun will make an appearance, especially in the afternoon. The low that I originally thought would stay south of us will affect our area on Monday with light snowfall as the warm and moist southwesterly flow ahead of the storm overruns the cold arctic airmass left by Saturday’s wave.
Additionally, another arctic wave rotating around the Hudson Bay vortex will force the California low westward and turn our flow to the northwest Tuesday evening, increasing very light and dry snowfall. Wind speeds stay very low as they decrease behind the departing low to our south, and that will limit accumulations Tuesday and Tuesday night. At this point, I would guess 1-4” on both Tuesday and Wednesday morning, with light snow showers and minimal accumulations continuing through day Wednesday.
Another small break on Thursday before the Siberian vortex splits and cross polar flow brings another round of bitterly cold air across the North Pole and into western Canada. There is a fair bit of uncertainty with respect to the interaction of this arctic airmass and the polar jet carrying mild and moist Pacific air, but an active pattern, especially for the west coast is likely for next weekend.
Thursday, January 30, 2014
The Steamboat ski area reported 8” at mid this morning, with 9” up top, and ski patrol updated the gondola line with a 10” report just before 8am. There was some wind affected snow in most places, but not nearly as bad as I had feared. Any groomer skied bouncy and creamy, unless the pitch steepened enough to put you in contact with the frozen subsurface. Off-piste was a bit inconsistent as even the 13” I measured in Shadows was not enough to completely separate the skier from the surface on every turn. Some sequences of turns were smooth, deep, consistent and bottomless in the untracked but heavy and dry powder, but certainly not all.
Even though the temperature was 13F up top, the snow crystals were small and very heavily rimed, which means they were covered with enough frozen water to obscure their original shape. This is not surprising considering the very wet flow off the Pacific with a moisture tap back to the Hawaiian Islands. The end result was that the dry snow packed together fairly efficiently as it fell, creating snow to liquid water ratios that I’m guessing were around 10:1 or slightly less, which is heavy for us.
Untracked and heavily tracked areas skied the best as they were the most consistent. Lightly tracked was inconsistent as you would alternately accelerate when skiing though a track, and then decelerate when re-entering the untracked. There was not substantially more snow at the top of the hike on Morningside, but the run down North St. Pats was great since I was able to find mostly untracked snow alongside the cliff bands.
I had not planned on skiing until exhaustion, but the turns today required lots of energy in the heavy, but dry snow. I’m guessing they received about 4” of snow up there during the day, so I would expect the report tomorrow to be on the light side of my 8-16” forecast, and more likely closer to 6-12” It also currently appears the wave for Friday may be just far enough south to produce only light snow Friday night, so the original and optimistic 6-12” may have to be scaled back as well.
Wednesday, January 29, 2014
Clouds have overspread the region in stable flow this morning. The storm cycle is forecast to begin later this afternoon as cooler air associated with a cold wave dropping down the west side of the Hudson Bay vortex interacts with the Pineapple Express mentioned in my last blog. Light snowfall will give way to heavy snowfall around midnight that will persist through at least Thursday, creating 5-10” by the Thursday morning report and 8-16” by the Friday morning report, with some Steamboat Magic occurring between report time and opening time.
Current model trends have us in a break during the morning Friday as the first storm moves east of our area. Another Pacific wave in the Pineapple Express is forecast to slam into the northern California coast early Thursday, and this may affect our weather later Friday. Models are struggling with the northward extent of this second more southerly wave, and that will determine if heavy snows continue Friday afternoon and through the night.
If the Pacific wave stays far enough north, heavy snows will continue through the night Friday, producing another 6-12” by the Saturday morning report. Only light accumulations are expected by Saturday morning if the wave stays south of us.
During the weekend, the polar jet stream is forecast to buckle and drop a storm into southern California, backing our flow further to the southwest and eventually ending snows by late in the weekend as the storm stays south of Colorado.
The weather for next week is looking seasonably cool with only light snow expected for a few days around midweek as cold waves continue to rotate around the Hudson Bay vortex. It appears the cross polar flow mentioned in my earlier blogs will allow very cold air from Siberia to enter the North American continent around next weekend. Another storm cycle may develop if this air is far enough west to weaken a rebounding west coast ridge and allow more Pacific energy to undercut it.
Monday, January 27, 2014
The current complex forecast has shown signs of stability the past few model runs, increasing confidence that a possible 20-40” long-lasting snowfall event will grace our area for the second half of the workweek and into the weekend.
The Steamboat ski area reported 3” mid at 1pm and 2” up top today, but light snow will continue until about midnight, producing a 4-8” report by Tuesday morning. Tuesday will be a beautiful in-between day before the weather fireworks begin by mid-day Wednesday.
Similar to today, another cold wave drops down the west side of the Hudson Bay vortex and phases with a Pacific wave in the undercutting polar jet stream that is forecast to contain copious quantities of subtropical moisture. Indeed the moisture feed extends all the way from the Hawaiian Islands earning this branch of the polar jet stream the moniker Pineapple Express. The end result is our flow backs from the north to the west, warming temperatures and increasing winds. Snow is currently forecast to begin on Wednesday with periods of heavy snowfall lasting through at least Thursday morning, creating 6-12” by the Thursday morning report.
Most models then slam another undercutting wave into the northern California coast early Thursday, and waves of energy should continue to travel over our area, still interacting with cold waves from the north rotating around the Hudson Bay vortex. There is some uncertainty here, but currently I’m thinking another 8-16” by the Friday morning report if things hold together as forecast.
If the Pacific wave does travel over our area relatively intact, heavy snows will continue through the day Friday followed by moderate to light snow, producing another 6-12” by the Saturday morning report.
During the weekend, the polar jet stream is forecast to buckle and drop a storm into southern California, backing our flow further to the southwest and eventually ending snows by late in the weekend. I would expect another 3-6” by Sunday morning as this storm cycle ends.
Sunday, January 26, 2014
The uncertainty displayed in the numerical model guidance this past week is resolving itself as Pacific energy is forecast to undercut the persistent west coast ridge. This is the first time this season the polar jet stream is finally forecast to carry seasonably warm and very moist air into the west coast, bringing snow to the drought-plagued ski resorts located there and bringing a Pacific storm track into the Great Basin and Rockies.
Before this new regime takes hold, a weak but cold storm currently to our north will bring clouds to the area later today and light snow beginning around midnight. The westward extent of this storm is still bouncing around in the models, but I would expect snow all day on the hill tomorrow with 1-2” by Monday morning and possibly 3-6” by Tuesday morning, with most of that occurring by midnight Monday.
A break on Tuesday before the undercutting jet stream slams into the northwestern coast by late Tuesday. Similar to tonight, another cold wave drops down the west side of the Hudson Bay vortex and phases with a wave in the undercutting polar jet stream that is forecast to contain a fair bit of subtropical moisture. The end result is the polar jet stream is pushed southward to California and our flow backs from the north to the west, warming temperatures and increasing winds.
Snow is currently forecast to begin on Wednesday, and the interaction of the polar jet stream with the cold waves rotating around the Hudson Bay vortex will keep our weather snowy through the week. Additionally, the polar jet stream is forecast to buckle by the weekend, dropping a storm into southern California by the weekend and backing our flow further to the southwest. Snows are likely to continue through the weekend as this very dynamic weather pattern evolves.
With so many interacting pieces, predicting snow amounts is difficult at this time, but an extended period of moderate to heavy snows with periods of high winds is likely starting Wednesday and lasting through the weekend.