Forecast snow amounts increase for Christmas
Tuesday, December 24, 2019
A quick note to update my forecast from last Sunday for more snow. Shorter-range models have indicated the possibility of banded snowfall on Christmas Day over Steamboat Springs, which could create snowfall rates as high as 1” per hour at times tomorrow. The banding can occur when the usually broad and diffuse lift associated with an unstable atmosphere within a storm is concentrated along relatively narrow and roughly parallel bands, and can result in localized moderate to heavy precipitation at times.
I still expect the storm to get going this evening, with 1-4” expected by the Christmas Day ski report. But after a break early in the morning after the initial wave of the storm passes through, we should see sometimes moderate to even heavy snowfall at times from mid-morning through the afternoon leaving another 2-5” of snowfall at mid-mountain by the time the lifts stop turning.
While the heaviest snowfall will be over by around midnight on Wednesday, with another 1-4” overnight yielding 3-9” for the Thursday morning report, much lighter snows will continue through the day Thursday with only minor additional accumulations expected.
Drier air briefly works into northern Colorado on Friday before a quick moving Pacific wave mixes with some very cold air from Alaska and western Canada and brings sharply colder temperatures for the weekend. Currently, light snow showers are advertised for at least Saturday and possibly Sunday as well, but I’ll have more details on the weekend’s weather on my regular Thursday afternoon weather narrative.
Warm with increasing clouds ahead of a white Christmas
Sunday, December 22, 2019
Some morning clouds have given way to mostly sunny skies in Steamboat Springs this Sunday around noon, with the current temperature in town one degree above our average high of 27 F and the temperature at the top of the Steamboat Ski Area a balmy 37 F, accompanied by some breezy southwest winds.
The warm temperatures are a result of warm air being carried northeastward ahead of a large storm just off the northern California coast. The storm is expected to split tonight as additional Pacific energy approaches and forces the storm eastward on Monday and Tuesday. The evolution of this storm has varied within and between the weather forecast models over the last several days, making for an uncertain forecast. Right now, Monday looks similar to today, with Tuesday seeing increasingly thick cloud cover ahead of the storm in continued above normal temperatures. Snow showers are currently advertised to break out Tuesday evening, perhaps around midnight, with 1-4” of snow expected for the Christmas morning ski report as a cool front passes through.
Snow showers are expected to persist through Christmas Day into Thursday as additional Pacific energy interacts with the storm. Though generally of light intensity, there is a possibility of better snowfall for a time Wednesday afternoon and overnight as a wave of energy that is forecast to eject out of the storm may or may not pass close to our area. So there could be another 1-4” for the Thursday morning report.
A break in the unsettled weather is likely for later Thursday or Friday that extends through most of the upcoming weekend before significant weather forecast model disagreement appears. The American GFS want to keep the storm moving well to our south with a dry and cool forecast for the beginning of the next work week, while the European ECMWF hangs the storm far enough back to bring light snow chances back to our area. More details should be available by my next weather narrative on Thursday afternoon.
Dry with warming through the weekend
Thursday, December 19, 2019
The weather will stay dry in Steamboat Springs with continued warming through the Winter Solstice weekend, which occurs at 9:19 pm on Saturday and makes that night the longest of the year. Warm and pleasant weather will last through Monday before several waves of Pacific energy and moisture turn our weather unsettled starting around Tuesday, Christmas Eve day.
After a relatively warmer morning in town with a low temperature of 2 F this Thursday, just two degrees below average, an anemic and moisture-starved wave will pass over the Rocky mountains today, barely bringing even clouds to our area. However, some cool air associated with the wave will keep temperatures in check today and create another chilly morning in the Yampa Valley for Friday. But warming commences during the day and increases through the weekend and into Monday under mostly sunny skies as a ridge of high pressure builds over the West ahead of a Pacific storm expected to affect California late Saturday and Sunday.
The evolution of this storm has not been well-forecast so far, with a lot of inconsistencies both between and within successive weather forecast model prognoses. This is not unusual with storms off the West Coast that will be affected by additional upstream Pacific energy and are forecast to mix, to some degree, with cold air from western Canada. The differences arise from not only the paucity of data over the Pacific Ocean, but also how the weather forecast models incorporate those data.
This is a long way of saying that there is considerable uncertainty in the timing and strength of storms passing over our area as soon as Tuesday, Christmas Eve day. There is a lot of time for the weather forecast models to iron out their differences by my next weather narrative on Sunday afternoon, but currently the storm is expected to undergo some sort of split by the end of the weekend even as additional Pacific energy rounds the base of the storm.
Clouds will increase later Monday into Tuesday as moisture is drawn northward over our area in southwest flow ahead of the storm. Snow showers are currently advertised to break out during the day Tuesday and last overnight before ending by Christmas as a cool front passes through.
After a likely break on Thursday, another couple of storms are forecast for around the Thursday/Friday and Saturday/Sunday time frames, though their speed and track are too uncertain for a forecast at this time. Check back for my next weather narrative on Sunday afternoon for more details.
Quiet and cold weather with warming starting midweek
Sunday, December 15, 2019
The long-duration and well advertised snows have ended over the Steamboat Springs area this Sunday morning, with the Steamboat Ski Resort reporting three day totals of 22.5” of snow at mid-mountain and 27” up top. Cold temperatures are now observed behind the storm and are expected to last for the next couple of days before we see warming, first at the higher elevations, by later Tuesday and Wednesday. And other than some light snow showers during the day Monday and possibly on Thursday, quiet weather is expected through the upcoming week before the next possibly significant storm approaches the West Coast around late next weekend.
Colder overnight temperatures than recently observed were right at our average of 5 F this Sunday morning, with high temperatures over the next few days staying ten degrees or so below our average of 27 F thanks to the cold air mass behind the storm, fresh snow cover and low sun angle.
After a precipitation-free and partly sunny day today, a trailing and weak wave of energy and moisture will move over our area during the day Monday. Some light snow showers are possible at the higher elevations, possibly leaving several inches of snow during the day that would be reported Tuesday morning.
A ridge of high pressure then moves over our area for Tuesday and Wednesday, bringing plenty of sun and warming, first noted at the higher elevations. Mornings in the Yampa Valley will stay chilly with low temperatures around zero as the clear nights, light winds and fresh snow cover allow the ground to efficiently cool, and sets the stage for early-day temperature inversions, where the air is actually warmer higher up on the hill than it is in town.
The ridge will keep moving eastward thanks to a moisture-starved storm that will cross the central West Coast on Wednesday and move over our area on Thursday. At this point, not much more than some clouds and cooler daytime temperatures are expected before a stronger and longer-lasting ridge of high pressure builds over the Rocky Mountains for Friday and the weekend.
So, much of the Rocky Mountain region should see a beautiful and warm Friday extending through the following weekend. This looks to last into at least part of the following Monday before there is considerable uncertainty with respect to the next storm forecast to affect the West Coast around then. The weather forecast models indicate some sort of splitting storm, though the severity of the split and how additional upstream energy are handled is unknown at this time. I hope to have a better idea how this may affect our Christmas Eve day and Christmas by my next weather narrative on Thursday afternoon.
Long duration snow event extends through Saturday
Thursday, December 12, 2019
Snows have started this Thursday morning in Steamboat Springs ahead of time, and will wax and wane over the next two and a half days leading to storm cycle accumulations that could total 16-32” by Saturday afternoon. The most most intense snowfall on Thursday night and then again from Friday night into Saturday morning will be accompanied by stout westerly to northwesterly winds and will make travel difficult to impossible over mountain passes. Much colder but drier air sweeps in behind the storm for Sunday and extending to midweek, with warming, especially at the higher elevations, expected for the remaining work week.
Note that I have just added some additional numerical guidance to the Snowalarm Home page that shows the temperature, wind and precipitation forecast from the Colorado Avalanche Information Center for the Steamboat Ski Area for both Thunderhead and the top of Mt. Werner over the next three days. This represents the high-resolution version of the weather forecast model that office runs every 6 hours, and is useful for getting an overview of a predicted storm. To access the data, click on ‘Precipitation Forecasts’ and scroll down the container until you see the ‘Latest CAIC Point Forecasts’ heading. Also, previous forecasts can be viewed with the ‘Previous forecast / Next forecast’ links at the bottom of the image and give a useful indication of how the forecast is trending. Note that the scale can change when navigating through successive forecasts. Be cautioned that this is one of many weather forecast models I review before making a forecast, and as such may have its own ‘opinion’ at times.
Back to the forecast, a strong Pacific jet stream is carrying subtropical moisture from around Hawaii inland and across our area. Lots of good things associated with this, including moisture and upward motion associated with the jet stream, several embedded waves within the flow and generally northwest flow which is good for orographic, or terrain-driven, atmospheric forcing over the Park mountain range. The relatively light snowfall will continue today leaving 2-4” at mid-mountain by close. However, an embedded wave brings a cool front through our area in favorable northwest flow early this evening, increasing snowfall rates to an inch or more per hour at times from sunset or so through the overnight. Along with the wind, travel will quickly become difficult to impossible tonight over the mountain passes. I would expect 5-10” overnight which would yield 7-14” of snow for the Friday morning report.
Snows are expected to at least decrease, or even end, during the day Friday, though continued windy conditions will keep travel difficult.
Snows pick up again and turn moderate to heavy Friday night and Saturday morning as a second embedded wave in northwest flow begins to move over our area. Travel will become more difficult or impossible again through that time as snowfall rates of an inch per hour or more occur at times along with continued windy northwest flow. Another 6-12” of snow is currently forecast for Saturday morning, with snowfall rates decreasing in the morning and tapering off in the afternoon. But we could see another 3-6” during the day which would make the storm total 16-32” by the time the lifts stop turning Saturday.
Though our significant snowfall will end around then, a third colder wave is forecast to take a more southern route through the Rocky Mountains, bringing significant snowfall to southern Colorado. There is some uncertainty with the track of this part of the storm, but right now we could see some light snowfall Saturday night associated with a strong cold front that will bring much colder temperatures for Sunday that will extend into the work week.
At this point, we will be on the edge of additional snow showers on Sunday, but the sun should return for a chilly and dry Monday, Tuesday and possibly some of Wednesday before warmer air associated with a ridge of high pressure behind the storm moves over our area by Wednesday.
