Monday, February 9, 2015
After another sunny and unseasonably warm day today, a storm currently over northwest coast will strongly split as it interacts with what has been a very dominant west coast ridge. There will be snow showers above the valley floor later tonight and Tuesday as the northern part of the splitting wave travels north of the area, with an inch or two likely falling overnight and again during the day. Unfortunately, the southern split looks to stay west of our area as it is forecast to eventually loiter over Baja by Thursday.
A dry wave from the north will graze our area on Wednesday and keep temperatures cooler than they’ve been recently, though they will still be warmer than average.
The west coast ridge quickly rebounds for Thursday and Friday bringing more record or near-record warmth to the area. Another grazing wave from the north will likely knock temperatures back on Saturday before they rebound by Sunday.
There is much forecast uncertainty by early to mid next week as models struggle with the evolution of the west coast ridge as it is attacked by Pacific energy. Additionally, this Pacific energy may or may not interact with the loitering Baja cutoff low and additional waves of energy rotating around the Hudson Bay vortex from the north. This leads to some hope that we may be returning to a snowier pattern sometime next week as the west coast ridge breaks down.
Monday, February 2, 2015
I had about 4” of now on my deck at 6:30 am this morning and an additional inch fell by 9 am. I have to admit I was a bit surprised this morning as I expected only several inches today as a wave moved over our area in moist northwest flow, but I discounted the model forecasts as they have not been verifying well for us this January. Furthermore, the European ECMWF model insisted on a much drier forecast, and again the American GFS provided a superior forecast for today. As a result, I will base my forecast on that model for the following week.
Two additional waves with similar trajectories to this morning’s wave will pass over our area Tuesday morning and Wednesday, with the Wednesday wave looking the most impressive of the three.
Snow should taper off today but begin again tonight, and I expect 2-5” on the hill by tomorrow morning. As today, snowfall rates should taper off during the day Tuesday before increasing again Tuesday night. This third wave looks to have more cold air and more dynamics associated with it, leading to a more prolonged event lasting through the day Wednesday and into the evening. I would expect 4-8” of snow for the Wednesday morning report, with an additional 3-6” during the day and overnight which will be reported Thursday morning.
A ridge moves over our area on Thursday, ending the snowfall but leading to a spectacular couple of sunny winter days for Thursday and Friday. Pacific energy is then forecast to flatten the ridge and lead to increasing cloudiness on Saturday and the possibility of some showers late in the day and overnight.
The ridge is forecast to rebound for later Sunday and Monday before another wave of Pacific energy threatens our area with showers around Tuesday or midweek. There is considerable model disagreement on the evolution of that storm.
Thursday, January 29, 2015
A portion of the cutoff low currently off the northern Baja coast will move inland over the next few days, spreading precipitation first into Arizona and New Mexico by Friday and then southern Colorado by Friday night. After a sunny day today, clouds will overspread the area tomorrow. There is uncertainty with regards to the northern extent of the precipitation, with our best chance of showers from Friday afternoon through Saturday afternoon before a dry wave rotating around the persistent Hudson bay vortex in northwest flow brings clearing to the area by Saturday night.
Due to the warm nature of the storm and lack of much wind, I expect modest accumulations at best, with optimistically around 1-4” falling by Saturday morning, Anything under about 6” would mark this as the driest January since the Steamboat Ski Area started record keeping in 1979!
The Hudson Bay vortex is forecast to further expand westward over the Canadian plains this weekend and into next week, and this increases the chances of snow for our area as cool air moves southward. Again, this will be a battle between the arctic airmass to our north and the persistent west coast ridge; periods of light to moderate snow can be expected Monday and Tuesday as a significant push of cool and modestly moist air moves over our area in northwest flow.
Additional weaker waves of energy are forecast for most of the rest of the workweek, leading to the possibility of additional light snow, though it is not clear if these will be productive as they battle with the flattened west coast ridge.
The west coat ridge appears to win by the end of the workweek leading to some warming and drying headed into next weekend. There is large model uncertainty after that as Pacific energy is expected to either weaken or ride over the ridge, hopefully leading to a snowier pattern change heading into mid-February.
Friday, January 23, 2015
Your snow dances have not been working. Please escalate the rituals to sacrifices immediately!
A wave in the western Great Basin will drop southward and form a cutoff low around the Baja peninsula this weekend. Additionally, a wave traveling over the top of the west coast ridge will pass to our northeast mid-weekend, dragging some cool air and the possibility of showers over our area for Sunday. There is uncertainty as to how far west the wave will travel so the there may be no snow or optimistically an inch or two during the day.
Temperatures will warm dramatically early in the workweek at all elevations, making the weather for those days feel almost springlike. The cutoff low loitering near Baja will have entrained substantial subtropical moisture and is forecast to move northward back into the Great Basin around Wednesday as some Pacific energy approaches from the west. Models are struggling with the track of this storm as it moves underneath the dominant west coast ridge, and our precipitation will be dependent upon how far east the cutoff low is from us.
Unfortunately, this will be an unseasonably warm storm, meaning any precipitation we do receive on Tuesday night or Wednesday will be rain below 9000 feet or so. But there may be some cooler air on the backside of the storm if the track is in our proximity, so that storm is a bit of a wildcard.
The weather looks to clear after the midweek storm as another Baja cutoff low is forecast to be established, leaving us in the quiet weather between that storm to our southwest and the arctic air to our north and east. Some longer term models show Pacific energy eventually moving over us after that weekend, but there is too much uncertainty in the medium term to have much confidence in those solutions.
Thursday, January 15, 2015
A ridge currently over the Great Basin will keep sunny skies over our area today and deflect most incoming Pacific energy to our north and east. Some of this energy will graze the area, with clouds increasing ahead of the first wave during the day Friday and light snow developing by Friday night. Light snow will continue into Saturday morning with minimal accumulations before a quick moving ridge behind the departing wave brings the sun back in the afternoon.
After a clear and cool Saturday night, clouds will move back into the area Sunday morning or early afternoon ahead of a series of grazing waves in northwest flow that will keep light snow in the forecast for Sunday afternoon through Tuesday. Snow amounts for Monday and Tuesday are expected to be light and in the 1-4” range.
Model uncertainty is large by Wednesday as the Great Basin ridge rebuilds westward near the west coast. All models predict some some mixing between the relatively warm and wet Pacific airmass as it travels over or through this ridge and the very cold and dry arctic airmass currently entrenched in the northern Canadian plains and resupplied by the Hudson Bay vortex.
Our weather next week and likely beyond will very much depend on the outcome of this battle between the west coast ridge and the Hudson bay vortex. Furthermore, the battle line is forecast to oscillate around our area, meaning a small change in the location of this battle will mean large changes in our forecast weather.