[Forecast courtesy of Powderchasers]
Mid-Long Range Forecast:
Summary
It’s been a rough year for most resorts in the West so far. The Pacific Northwest, Northern Idaho, Montana, and western Wyoming have had a decent winter, but even still most areas are below normal to significantly below normal for snow. Here is the current snow water equivalent % of Normal. The highest totals so far have been in the northern most Cascades and northern Rockies, however warmer than average temperatures have resulted in variable conditions at lower elevations. Northern Utah and Colorado sneaked out a decent storm just before Christmas which resulted in respectable conditions for the holiday. It certainly could have been much worse.
You can see northern Washington (Mt Baker), parts of Montana, (Montana Snowbowl, Bridger Bowl, Big Sky), and the Tetons are a little above normal while the rest of the Western US is below normal. The model failures of last week with respect to the Tetons did not help either. I wish I had better news for you, but the long range forecast does not show much hope for improvement. This can obviously change especially when looking out more than 14 days.
Recap:
Last week, the models showed significant snow for the Northwest, Idaho, and Montana. They indicated heavy snow for the Tetons as well. Here are a couple model runs from December 27th. Generally these models held up nicely with the exception of the Tetons.
Both the GFS and Canadian models showed significant snow for the Tetons. Ultimately, the moisture just didn’t make it far enough south, leaving the Tetons with minimal accumulations last weekend but decent amounts in the 7 days prior.
Extended Forecast: 7-10 days/ Long Range
The next 5-7 days will feature yet another ridge building into the West. You can see the 5 day average of 500 mb geopotential heights below.
The ‘warm’ colors indicate above normal heights which equates to High Pressure over the West. This results in warm and dry conditions, which will last until this weekend. Below are the temperature anomalies for the next 5 days. This map shows how much above/below normal the temperatures will be at 5k elevation. You can see the cold air in the East and warmth in the West.
Around January 6th the pattern becomes active again, with two possible storm systems moving into the West between January 6th – 10th. The first storm system looks to bring moderate snow to the PNW, Northern Rockies, and possibly the Sierra, Colorado and Utah regions. Below are the 500 mb GFS and ECMWF ensemble anomalies for January 6th. Both show a trough (storm system) coming into the West coast.
Below is the same time period with the GFS ensemble.
The second storm system, arriving around the 10th of January, may target areas a little further south, but it is too soon to tell. The GFS and ECMWF are in decent agreement for the second storm as well, shown below in the 500mb anomalies.
Right now, both of these storms look on the warmer side and snow levels may be an issue.
After this brief stormy period, I am sad to report that the Ridge (warm/dry conditions) looks to build back into the West. Once again, both the GFS and ECMWF agree that the Ridge will return following the brief stormy period. Height anomalies are shown below for January 14th (2 maps, Euro and GFS model runs).
Generally, this is a good setup for the East coast. Right now, it is too early to say how long this will last. There are some indications, for example from the National Centers for Environmental Prediction’s Climate Forecast System (CFS), that the warm and dry conditions could last through March. Below are the temperature and geopotential height anomalies for the months of January – March.
[images courtesy of AER]
You can see in the images above that this model is showing warm/dry conditions (red colors) in the West and cold/stormy conditions (blue colors) in the East for each of the next 3 months.
Further, some data from Judah Cohen and AER (Atmospheric and Environmental Research), reinforces the CFS’s forecast. One of the factors they examine is disruptions in the flow of cold air around the poles in the upper atmosphere. When these disruptions occur, specifically a weakening, it can often lead to a pattern that is cold/stormy in the Eastern US and warm/dry in the Western US several weeks after the disruption. The latest guidance from this approach indicates that this pattern could last through the end of January. In this type of pattern, there are prolonged periods of cold/storminess in the East and warm/dry conditions in the West, with short interruptions periodically bringing storms to the West before returning to the prior setup.
The good news? The CFS should always be taken with a grain of salt. It is not the most reliable and can often be wrong. If it were an incredibly accurate and reliable long range climate forecasting model, you would have heard about it by now and everyone would be using it. Also, the further out you look, the more time there is for things to change. So while overall the next 2-3 weeks don’t look great for the West, at least there is SOME activity and time for the extended forecast to change.
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Luke Stone- Long Range forecaster- www.Powderchasers.com
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