Long duration winter weather event starts tonight
Thursday, December 23, 2021
Clouds and some flurries are over the Steamboat Springs area this Thursday afternoon ahead of a long duration winter weather event that starts in earnest tonight. The question is not how many days it will snow for the upcoming week, but how many days it won’t as several storm systems are forecast to pass through our area. Travel will obviously be difficult or even impossible at times over Rabbit Ears Pass, even though it currently appears most favorable from Christmas afternoon through Sunday morning and on Monday, though elevations at and above pass level may see snows continue, though at much lesser intensities.
Currently an elongated trough of low pressure is centered off the West Coast and extends from the Yukon southwestward to east of Hawaii. Winds are from the southwest for all of the western U.S. ahead of the storm, with the southern part of the storm incorporating a relatively narrow stream of subtropical and even tropical moisture from east and southeast of Hawaii that meteorologists call an atmospheric river.
While there will be plenty of moisture over our area, there will not be much cold air as the winds from the southwest keep relatively warm temperatures overhead. But there will be enough for a couple of cool fronts to move through our area around midnight tonight and later on Friday, with snowfall rates increasing to an inch per hour or more at times under the heavier showers.
I would not expect the snowfall to begin in earnest until around midnight tonight when the first cool front moves through, and 3-6” of snowfall are possible on the 5 am mid-mountain ski report from the Steamboat Ski Resort. Even as that first front moves through, additional energy from the northern latitudes is forecast to reinvigorate the West Coast storm, keeping it mostly in the same place while upstream energy slingshots around the base of the storm and eventually moves overhead.
Weather forecast models have struggled with the exact timing of these waves of energy, with the latest forecasts bringing another cool front through our area later Friday, so expect periods of moderate to heavy snowfall through the day which should diminish overnight and into Saturday morning, though likely not stop. There could be another 4-8” during the day Friday and another 3-6” overnight for a 7-14” Saturday morning report.
There are several concerns with this storm and they all have to do with the prolonged period of southwest flow. Our best snows come when winds are from the northwest and we have strongly falling temperatures, and both of those things will not be happening until possibly next week. Another concern is windy conditions, especially tonight as gusts may exceed 60 mph on top of the mountain.
Winds from the southwest and the west are far less sheltered than the favorable northwest flow over the Steamboat Ski Resort, so relatively dense snow combined with wind may make for difficult skiing, though that is just a guess and I will personally have to investigate that hypothesis tomorrow!
So the weekend will start with a white Christmas, though snows should wane during the day and overnight. Another wave from the northern latitudes rounds the West Coast storm on Saturday, with weather forecast models bringing that overhead Sunday. There is more cold air associated with this than the Friday storm, so we may benefit from less dense and fluffier snow, though winds only briefly turn to the west or just north of west for a short time before temperatures rise as southwest flow again dominates for Monday.
However, there appears to be a break in the stream of moisture for the first part of Monday, so that is currently looking like a brief travel window. But, the next storm is on our doorstep by later Monday, with more significant snow possible for Tuesday, though the weather forecast models disagree on exactly how that West Coast storm will evolve.
I’ve gone well over my self-imposed word limit, even though there is lots more to write about as this long duration event begins. Feel free to ask me about it if you happen to see me on the hill, and be sure to stay tuned to my next regularly scheduled weather narrative sometime on Sunday (usually Sunday afternoon, but I want to leave my ski options open!) where I’ll discuss the upcoming parade of storms.
Beautiful start to the week followed by a snowy Christmas weekend
Sunday, December 19, 2021
Mostly sunny skies with temperatures in the twenties are over the Steamboat Springs area early this Sunday afternoon. More of the same is forecast to start the holiday-shortened work week before clouds increase on Thursday ahead of a long-lasting stormy pattern that may be around for the rest of this year.
Currently, a large trough of low pressure extends southward from the Gulf of Alaska towards Hawaii. Winds from the southwest ahead of the storm have tapped into a plume of subtropical moisture northeast of Hawaii, creating a relatively narrow but long atmospheric river, which in this case is also known as the Pineapple Express. While it is currently directed at the Oregon - Washington border, bringing copious precipitation to that area, the atmospheric river is expected to first move northward as the storm off the coast deepens and tries to form an eddy cut off from the main jet stream.
The main source of uncertainty in the past longer range weather forecasts that were valid this week involved a chunk of cold air from Siberia just now traversing the Bering Strait and how much of this cold air intensified the storm off the West Coast and how much traveled eastward.
The weather forecast models seem to have converged on the idea first suggested by the American GFS last week that most of the cold air will mix with the West Coast storm, forcing it to sink further south and bringing the atmospheric river with it. The end result is likely another massive storm for the Sierra Nevada mountain range, with some forecasts calling for up to 100” of snow starting Wednesday night and lasting through the Christmas weekend.
After the West Coast storm reaches its southern extent late Wednesday, it is then forecast to move east, bringing some of the atmospheric river with it. Weather forecast models have trended later with this eastward movement, and it now looks like we will see thick clouds over our area on Thursday, with relatively warm precipitation breaking out by Thursday night. It is not clear yet whether the lower elevations see any rain ahead of cooler air for Friday.
The cooler air on Friday will be associated with the bulk of the original West Coast storm, even as that area of storminess off the West Coast is reinvigorated by continued waves of cold air dropping southward from the northern latitudes. Expect the showers on Thursday night to become more persistent toward Friday morning, with moderate to heavy snows during the day.
Weather forecast models currently have the snows decreasing by later Friday, though they may not stop through the weekend as waves of energy and moisture continue to eject out of that persistent West Coast trough of low pressure. And at some point during the following week, that trough of low pressure is forecast to move bodily eastward, bringing more snow and very cold temperatures with it.
Several weather pieces will be moving around during our current stretch of gorgeous weather, and how those pieces interact will determine snow amounts for our area later in the week. So stay tuned to my next regularly scheduled weather narrative on Thursday afternoon where I’ll have snowfall guesses for Friday and a better idea of the weather for this Christmas weekend and the last week of 2021.
Next storm starts tonight with a cold but sunny start to the weekend
Thursday, December 16, 2021
Mostly sunny skies and chilly temperatures of 15 F at the Bob Adams airport and 13 F near the top of Mt. Werner are over the Steamboat Springs area this Thursday noon. Our next storm starts this evening with snows tapering off through Friday ahead of a cold start to a mostly sunny weekend.
A cold storm currently moving across the Great Basin will approach our area this afternoon with snow showers starting by this evening. Snows are expected to become more persistent and intense heading toward and after midnight with rates approaching an inch per hour at times before they start becoming more showery after the 5 am Friday morning ski report. We could see 3-6” at mid-mountain by that report, with Steamboat Magic bringing more accumulating snowfall between the report and when the lifts start loading.
While snows will become more showery and taper off through the day and evening, another 1-4” might fall and would be recorded on a quite cold Saturday morning ski report when temperatures both at the base and at the top fall to zero or below. Travel could be difficult at times over Rabbit Ears Pass from about midnight tonight through Friday morning under the heavier showers.
Though Saturday will start cold, the winds will turn to be from the northwest during the storm to the west after the storm and bring warmer and drier air overhead. Valleys will be slow to warm due to fresh snow cover and light winds, but mid and high elevations slopes should see high temperatures in the teens by Saturday afternoon and the twenties by Sunday afternoon under mostly sunny skies.
Meanwhile, a strong storm currently near the Aleutian Islands is forecast to strengthen as it approaches the West Coast and eventually form an eddy cut off from the jet stream. While these types of storms are notoriously difficult to predict due not only to the nature of the storm but the sparse observational network in the middle of the ocean, current forecasts have the storm staying largely off shore through at least the beginning of the short work week. The end result for our area will be continued mostly sunny skies and warming temperatures to start the week, with a chance of snow returning to our area around midweek or soon after.
Be sure to stay tuned to my next regularly scheduled weather narrative on Sunday afternoon where I’ll discuss what will hopefully be the start of a stormy pattern heading into the Christmas holiday.
Nice weather ahead of more snow Wednesday
Sunday, December 12, 2021
Mostly sunny skies and temperatures in the twenties, on their way to the thirties, are over the Steamboat Springs area this Sunday noon. Monday will be similar with about five degrees of warming before clouds and winds increase on Tuesday ahead of a winter storm now starting to pound the Sierras. The storm will move through our area like a freight train on Wednesday with moderate to sometimes heavy snows that will taper off through midnight. Thursday is forecast to be an in-between day ahead of a small storm forecast for Thursday night and Friday.
A large and quite-cold area of low pressure currently in the Gulf of Alaska has tapped into a warm and very wet stream of moisture originating from north of Hawaii. This so-called Pineapple Express is one example of what meteorologists call an atmospheric river due to its long fetch but relatively narrow width. While some of the mountains of California are forecast to receive multiple feet (or yards!) of snow over their three day storm, our effects will be far more modest by the time the storm gets here on Wednesday.
The storm in the Gulf of Alaska is forecast to elongate along the West Coast before the strong cold front associated with the storm makes landfall on Tuesday. Our winds will switch from the west to the southwest on Monday and increase on Tuesday as the storm approaches. It looks like the southwest winds will keep the dry air currently over our area for Monday and some of Tuesday, so Monday should be sunny and warm with high temperatures possibly breaching forty degrees.
Tuesday should start sunny, but clouds will increase later in the day as breezes from the southwest increase. Precipitation will likely hold off until midnight, but will be insignificant until just before the cold front blasts through what is currently forecast to be Wednesday morning.
Travel will likely be difficult over Rabbit Ears Pass along and just behind the cold front with blowing snow, slick roads and reduced visibility. A trailing wave timed for later Wednesday should keep lighter snows going until midnight, and there might be 4-8” of snow by the Thursday morning mid-mountain report, with about half that in town.
We’ll see a break for at least part of Thursday before another very cold storm forecast to cross the Pacific Northwest coast on Wednesday approaches our area. Currently, weather forecast models have this storm splitting as it moves over our area on Thursday night and Friday, so snowfall is expected to be less than the midweek storm, but with far more cold air.
The coldest air is expected for Saturday morning, and the cold air over the West may be setting the stage for a prolonged period of unsettled weather as we head into Christmas week. So stay tuned to my next regularly scheduled weather narrative on Thursday afternoon where I’ll discuss the end of week storm, the weather for the following weekend and what weather might follow.
Significant snow still likely with colder temperatures and drier snow after midnight
Thursday, December 9, 2021
The Steamboat Springs area is seeing a rain-snow mix in town with temperatures a few degrees above freezing and about 3” of snow on the mid-mountain and upper mountain powdercams with colder temperatures in the twenties. More wet snow is forecast for the higher elevations through midnight while the lower elevations will struggle with a rain-snow mix until this evening. A cold front will move through our area between midnight tonight and sunrise tomorrow, creating low-density powder that will quickly accumulate and create difficult travel conditions over Rabbit Ears Pass. Snowfall should wind down through Friday with the coldest temperatures of the season so far expected for Saturday morning.
After a disappointing storm that split to our south on Monday night and Tuesday and produced only 2” of snow at mid-mountain and summit when I called for 4-8”, some left behind energy did move overhead last night with an inch of snow falling by today’s morning ski report.
But there is still hope for significant snow from this last in a series of storms that is currently moving across the Great Basin. The winds from the southwest ahead of the storm are carrying very moist air overhead, with wet snow forecast to continue accumulating above 9000′ or so and more of the rain-snow mix down in town.
Temperatures should cool a bit as we head through sunset, so hopefully we see more snow down in town by then, but the real snow likely won’t start until the strong cold front associated with the storm moves through after midnight tonight. Snowfall rates could exceed an inch per hour at times as the front moves through, the atmosphere destabilizes and our winds shift to be from our favorable northwest direction. I would expect the bulk of the 6-12” expected at mid-mountain by the Friday morning report to fall during this time.
Snows will become more showery Friday morning, though some showers could be moderate to heavy at times in the afternoon as a trailing wave passes over our area. We could see another 3-6” of light and fluffy powder that falls on a relatively cold Friday with high temperatures in town barely reaching 20 F, around ten degrees below our average of 29 F. And a relatively frigid Saturday morning will see low temperatures reach to or even below zero, which will feel unreasonably cold after our last couple of weeks of warm temperatures, but will only be modestly below our average of 6 F.
The sun should return on Saturday and temperatures should warm closer to average in the afternoon as winds shift to be more from the west behind the departing storm and warmer and drier air is carried overhead. Even more sun and warmer temperatures in the mid-thirties are expected for Sunday.
While the warmer and dry weather is forecast to last through the beginning of the work week, another storm is forecast for around midweek. So stay tuned to my next regularly scheduled weather narrative on Sunday afternoon where I’ll attempt to dial in the details of our next storm, which also might be significant.
