Monday, March 13, 2017
A Gulf of Alaska storm has pumped up a ridge over the western U.S. that will lead to very warm temperatures for most of the coming week. A small disturbance ejecting from the storm will flatten the ridge and may affect the region with clouds and possibly light showers as it moves north of the Steamboat Springs area later Thursday and Friday.
The western U.S. ridge is forecast to quickly rebound for the weekend, quickly returning our temperatures to above normal.
Meanwhile, much further to our west off the coast of Japan, a large storm will form this week that is forecast to break down the dominant Bering Sea ridge over the weekend and allow a strong subtropical jet to cross the Pacific and eventually make landfall early in the next work week.
Additionally, the polar jet stream will no longer be diverted by the disappearing Bering Sea ridge, and cold air will pour into the central Pacific from the northern latitudes, further strengthening the subtropical jet stream. This pattern change may bring the return of long-lasting wet and stormy weather to the western U.S. around next midweek.
Friday, March 10, 2017
A couple of weather disturbances will move by the Steamboat Springs area tonight and Sunday before very spring-like weather returns for the following work week.
Models have come into better agreement with respect to how the polar and subtropical jet streams and the persistent Bering Sea ridge will interact over the coming week. Energy traveling down the east side of the Bering Sea ridge within the polar jet stream has formed a large low pressure system in the Gulf of Alaska, and a wave ejecting from that will move over northern Colorado on Friday night in northwest flow. Warm and dry weather will be observed again today ahead of that storm, with increasing clouds expected later in the day. The American models have trended weaker and further north with this storm, similar to the more consistent European ECMWF model, and I would optimistically expect only an inch or two by the Saturday morning report.
Clearing and drying will move over our area by Saturday afternoon and night, ahead of another wave of energy from the Gulf of Alaska storm in northwest flow timed for Sunday. This one has mixed with energy from the subtropical jet moving underneath the Bering Sea ridge, and will be a bit moister and stronger, but it is still unimpressive, and I would expect 1-4” by the Monday morning report, most of which will fall before sunset on Sunday.
More energy propagating southward in the polar jet will strengthen the Gulf of Alaska storm early in the week and pump up a ridge over the western U.S. states that will lead to very warm work week temperatures. A small disturbance may affect the region with clouds and possibly light showers as it moves over the area around midweek, but the American models have trended weaker and further north with this solution, similar to the once-again more consistent European ECMWF model.
Another wave moving through the subtropical jet undercutting the Bering Sea ridge mixes with the Gulf of Alaska storm and brings another disturbance near our area by the end of the work week. At this point, that disturbance also looks unimpressive as another round of polar jet energy travels down the east side of the Bering Sea ridge behind that storm and keeps the downstream western U.S. ridge intact.
Monday, March 6, 2017
The current cold and windy conditions will last through Tuesday as additional energy on the backside of the storm moves through the Steamboat Springs area overnight and tomorrow. 2” fell during the day today at mid-mountain with 4” up top, and with an additional inch or two overnight, I would expect a 3-6” mid-mountain report by Tuesday morning.
After another cold start to the day tomorrow, temperatures will warm to still-below-average in the afternoon, with snow showers being most numerous in the morning and tapering off later in the day. While winds will still be strong and gusty, they should shift from the west to the northwest and spare Mount Werner from the worst of the gusts as its mainly western aspect will be less exposed. I would expect and additional 1-4” during the day which will be reported Wednesday morning.
Breezy conditions will persist for Wednesday and Thursday as temperatures warm to above average before slackening by Friday.
There is a quick-moving storm that will pass by Friday night into Saturday morning followed by warming and drying for the first half of the weekend, but there is disagreement among the models as energy from the the polar jet stream traveling down the east side of the persistent Bering Sea ridge is partitioned. Some of this energy is forecast to move eastward over the U.S. and some is forecast to move southwestward under the Bering Sea ridge and possibly merge with upstream central Pacific energy from the subtropical jet stream. I have watched for a week as model solutions evolve, and I don’t have high confidence that any of them has the right answer yet.
That being said, after the possible Friday night event and the following warming and drying, there may be another storm late in the weekend that may be considerably moister as the wave originates from the possible merger of the polar and subtropical jet streams under the Bering Sea ridge.
Friday, March 3, 2017
A transient ridge over the Western U.S. has brought beautiful weather to the Intermountain West and the Steamboat Springs area. Cold air moving down the east side of the resurgent Bering Sea ridge has formed another cold storm in the Gulf of Alaska. Similar to previous storms, this is predicted to slide southward along the West Coast before moving across the Great Basin on Sunday, bringing winter weather back to the West late in the weekend through early in the work week.
Temperatures will continue to warm tomorrow ahead of the storm as winds increase from the southwest and clouds begin to overspread the area. This trend continues on Sunday with winds increasing further, and energy ejecting from the storm will increase the chance of showers by later Sunday.
There is model disagreement with respect to the timing, but a strong cold front looks to move across the area late Sunday or Monday accompanied with a burst of accumulating snowfall. Snow showers look to continue behind the front in the cold and unstable northwest flow, though at this point the best moisture is forecast to quickly erode behind the front, limiting total snowfall. Anticipated snowfall amounts will almost surely change as we get closer to the event, but 4-8” is a reasonable guess by Monday afternoon.
A trailing wave late Monday or early Tuesday reinforces the cold air and restarts the snow showers that will be most numerous overnight and during the first half Tuesday.
Warming and drying will occur midweek for a day or two as another transient ridge moves over the West. However, there is considerable uncertainty after that as models are very inconsistent in handling additional energy moving down the east side of the Bering Sea ridge and how much of that energy interacts with Pacific energy undercutting the ridge.
The Bering Sea ridge was observed during the first half of our winter, and I am encouraged to see it reappear as we received good snowfall from that pattern. While the specifics are murky at best, I am hopeful we will see another active weather regime as spring approaches.
Monday, February 27, 2017
A deep trough of low pressure along the West Coast will move eastward across the Great Basin today, with several pieces of the storm bringing snows to the Steamboat Springs area starting this this afternoon or evening. The first part of the storm brings breezy southwest flow to our area today, with the best upward forcing staying north and south of us.
However, a cool front does pass through the area this evening, backing mountain-top winds slightly to the west and limiting accumulations as the Steamboat Ski Area is most favored with northwest flow. I would expect the best snows from this first part of the storm to be associated with this front Monday evening, leaving 1-4” of snow for the Tuesday morning report.
While we may see some snow showers for the first half of Tuesday, trailing energy from the Pacific Northwest brings a stronger cold front through northern Colorado later Tuesday, backing the winds to the northwest and bringing light to moderate snows for a time.
Amounts may be limited by decreasing moisture just as the winds turn to our favorable northwest direction, but we should see around 3-6” by a very cold Wednesday morning.
Showers will decrease for a time Wednesday before picking up again later in the day as a final wave in northwest flow brings another push of cold air and upward forcing. Again, moisture is sparse so I would expect 1-4” for the Thursday morning report.
At this point, a dry wave is forecast to move north of our area early on Friday before much warmer and drier weather is advertised to invade our area later in the day. The weekend forecast is uncertain , but generally unexciting as weak waves in westerly flow may suppress the driest air to our south and could bring clouds to northern Colorado.