The Model Roller Coaster Has Left The Loading Platform

11/17/21 Wednesday 1:40 pm

In a recent interview, I was asked “what makes forecast models so interesting when storms form and head our way? My response was that I found it interesting how many billions and billions of dollars are spent on developing and improving weather and climate models and how inaccurate they usually are.

The GFS operational model had this 24 hours ago for next week’s storm.

24 hours later it has this

That is why I said yesterday that I will stick with the ensemble models for a few more days.  Here are the ensemble precipitation forecast models for the Canadian, the GFS, and the Euro family of models.

Canadian liquid

GFS liquid

The Canadian model has the most run-to-run consistency at this point. The GFS and Euro both took a more southerly path with this “cut off low”. Cut-off lows are very hard to forecast because they move separately from the west to east current moving across North America. I did notice that the CPC (Climate Prediction Center) bumped our area up to the first percentile tier for above-normal chances of precipitation in the next 6 to 10 days. The first tier is categorized as “Leaning Above” and it means they think we have a 33% to 40% chance of above-normal precipitation in that time period.

I don’t like the probability scheme being used as a forecast because it is too confusing and it is not a forecast. That reminds me, I have not addressed a question I always get asked about, the NOAA Winter Outlook. They use the same type of probability scheme for their Winter Outlook that they do for the 6 to 10 and 8 to 14-day outlooks. The Winter outlook is always misinterpreted by the media because they think it is a forecast. I saw that a few weeks back. Here is NOAA’s Winter Outlook.

What they are actually saying is that they believe there is a 33% to 40% chance that we will have below-normal precipitation this winter. What usually gets reported is that NOAA is forecasting 33% to 40% less precipitation this winter. The two statements are very different.

Here is an actual winter forecast. Courtesy of WeatherBell Analytics.

I know which one I am rooting for…

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A Second Look At Thanksgiving–Things Are Getting Interesting!

11/16/21 Tuesday 1:20 pm

What a difference! The outlook was pretty boring Sunday morning when I posted last. Then the later day runs started showing a completely different picture for next week. By Monday all of the ensemble model families plus the latest runs of the GFS and Canadian were showing us flipping into an active weather pattern before mid-week (next week). Today the individual latest run of the Euro is coming on board and the Euro ensemble members are coming in a little heavier.

Most of the models are showing the activity getting started late on Tuesday or early Wednesday with several waves delivering a couple of days of precipitation. They show the earlier waves keeping the snow at or above 8,000 but dropping to the lower levels by Thanksgiving.

It is very encouraging to see agreement across the ensemble models. I don’t want to jump on the hype train just yet, but I am becoming optimistic. Enough so that I am going to go back to posting daily.

I received a couple of emails asking me about a forecast for the lunar eclipse overnight Thursday/very early Friday morning. At the moment, two of my three cloud models are showing nearly full cloud cover. I will update on that each day for those who are interested.

Here are the current precipitation forecasts from the ensemble family models.

Canadian ensembles

Liquid

Snow

GFS ensembles

Liquid

Snow

Euro Ensembles

Liquid

Snow

Sometimes (not always) the ensemble runs lag the individual model runs because it is one model run instead of the average of 20 to 50 model members.

In the case of the GFS and Canadian which were the first models to pick up on this change for next week, there is a huge difference in totals.

Canadian

Liquid

Snow

GFS

Liquid

Snow

Let’s hope this trend continues, but for now, I am sticking with the ensembles for a few more days.

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Thanksgiving Week First Look

11/14/21 Sunday 7:15 am

I thought I’d better check in with everyone during this extremely dreadful boring weather pattern. The ridge has been dominant across the Western States. Moisture rides along the top of the ridge starting from the Pacific Northwest and then across the northern tier of states. This is not an unusual pattern for November, it is more common than not for our area. You may remember seeing this happen a number of times where Jackson Hole and points north get hammered with snow. Occasionally the snow will drop into the Dakotas. Eventually, systems will start sneaking in under the ridge or the ridge will flatten out and our winter will begin.

Snowlovers can’t wait for that to happen! It may take a while. In one of our top recent snowfall winters (2018-2019) it took basically until New Year’s day for the storm track to drop south. I had high confidence we were going to have a big winter that year, and I spent a lot of time answering emails trying to talk people off of the ledge as we waited for winter to kick in.

I am not as confident this year about the winter. I don’t know that I will attempt a Winter Outlook. My current thinking is that this year will have some of the characteristics of the 2008-2009 winter. We had a few big storms that were memorable. Most of the snow fell from late December to late January. It was cold, and spring came early. Another winter that comes up on the analog list is 2007-2008, but it is not as heavily weighted. 2007-2008 was a big snow year so it still keeps things interesting. Analog years are simply past years that experienced similar climatological conditions to the current year.

I am keeping my eyes on the ensemble (multi-model) forecasts. These models look 15 t0 16 days into the future and 30-50 versions of their model family produce the average forecast of all of those model members.

This week, the storm track will again stay to our north. There have been a few outlier model runs showing some late-week flurries, but nothing significant.  One of the best ways to predict the storm track is to look at the upper air projections for low or high-pressure anomalies.

Here are those model runs for the GFS ensemble and Euro ensemble members. The blues and greens are projected troughs of low pressure. The orange and red are the ridges of high pressure. The white and yellow are usually a typical zonal flow pattern.

Euro

GFS

With the next maps, you will see that the precipitation falls heaviest under the (blue) areas of low pressure.

Euro CONUS

Euro SW US

GFS CONUS

GFS SW US

So, for now, it does not look like there will be too many local travel concerns. Feel free to hit me up for out-of-state travel concerns beginning Wednesday this week. Make sure you include dates, travel methods, and routes.

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Snow Later Tonight Up North

Models still show snow breaking out in the early evening hours over the higher elevations in the northern portions of the forecast area. I would not be surprised if the onset slowed based on the apparent position of the disturbances to our west and the stalled front on the eastern side of the divide.

Here are the latest precipitation maps

GFS

Canadian-this makes the most sense orographically

German

Euro-not too sure about this

Given the latest model runs, I have not seen enough to warrant changing the forecast I posted yesterday.

3 to 6 inches of snow from Telluride over to Red Mountain Pass. 1 to 3 inches of snow will be possible around Silverton and Molas Pass. A dusting to an inch will be possible for Purgatory, Coal Bank, and Wolf Creek.

This will move out tomorrow, the ridge will pop once again and the boring weather will continue. As far as next week goes, it is too early to tell. The deterministic models backed off the storm. The ensemble (multi-model) runs are trying to flatten the ridge mid-week. I do expect a pattern change before the end of the month. I am just not sure when it will be.

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Snow For The North Tuesday Night, Snow For Lower Elevations Next Week??

Monday 11/8 12:30 pm

Models have come into better agreement in regards to timing and precipitation totals for the next storm. Snow will break out over higher elevations after 6 pm Tuesday. Snow levels will fall to around 8,000 feet by Wednesday morning. It still appears the highest totals will be over the northern portions of the forecast area.  3 to 6 inches of snow will accumulate from Telluride over to Red Mountain Pass.

1 to 3 inches of snow will be possible around Silverton and Molas Pass. A dusting to an inch will be possible for Purgatory, Coal Bank, and Wolf Creek.

The models are already sniffing out the next storm! It looks like it could approach our area next week around the 17th or 18th.   At this point, both the GFS and the Euro are showing a significant cold snowstorm. All three models are showing a pattern change with deep low pressure over the Rockies. Let’s hope this trend continues!

My next update will be on Tuesday afternoon. I will be posting precipitation maps for tomorrow night’s storm so stay tuned. Thanks for following and supporting the site!

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Tuesday Night Storm

96 hours later, the models are still not consistent in their precipitation forecast totals for the next storm. Here is what I can tell you. A storm will likely brush by mostly the northern portions of our forecast area. Precipitation should start sometime on Tuesday, most likely between late afternoon and midnight. Depending on what time the precipitation starts the snow level should be at or below around 8,700 feet. Light snow will continue throughout the overnight hours and move out during the day on Wednesday. Red Mountain and Telluride look like they will be the main beneficiaries of this storm.

How much precipitation falls is the question. Every 6 hours the Euro and GFS models are flipping back and forth on their totals. The Canadian model was very aggressive in its previous 3 runs. It showed a significant storm and included much of the central and some of the southern portions. Then, last night it gave up on all of that and fell into line with the Euro and GFS. As I said those two models are flipping back and forth, but they are only forecasting 2 to 5 inches (in their last 4 runs) of snow from Telluride to Red Mountain, with a dusting to an inch or so for other areas. For what it is worth, the German model has been showing higher totals and is showing more widespread precipitation throughout the forecast area.

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I Have Issued A BWW

Wednesday 11/3

Boring Weather Warning for Southwest Colorado.

If you like dry weather you are in luck. I expect no precipitation over the next 6 or 7 days. It will be a good time for outdoor projects or activities. High pressure is going to build in over the area.

As I mentioned yesterday, the models are in relatively good agreement that storms will move into the region during the Wednesday, November 10th to Friday, November 12th time period. The models are currently favoring the northern portions of the forecast area for snow. However, everything could change between now and then.

It will be a colder storm, as the trough drags down cold air from Canada. It may have a weak AR component. The jet is going to be involved as well. A lot to keep an eye on.

Here was the latest Euro weekly run for snow in November.

I will be posting as I see interesting model runs between now and then. Thanks for following and supporting the site!

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A Blip In The Weather Pattern

Tuesday 11/2/21 8:55 am

Energy from the system to our west is moving into the area. Most of the fun is up north but there are a couple of exceptions. There are a few flakes falling mainly above 10,000 feet. Radar is indicating some light rain showers but I don’t believe they are hitting the ground below 9,000 feet. Here is the current radar (8:20 am).

 

Here is the latest high-resolution model run for precipitation today.

Liquid

After this system moves out our next best chance of a storm moving into the area will be in the  Wednesday, November 10th to Friday, November 12th period.

Snow Forecast for today

Purgatory (snow stake): A dusting to an inch

Telluride (snow stake) Molas Pass, Coal Bank Pass: 1 to 2 inches

Wolf Creek: 1 to 2 inches

Red Mountain: 2 to 4 inches

I am reasonably confident that this system is going to move out by this evening. I do not expect travel to be impacted tomorrow. I did see something on the surface map that has me scratching my head and could change things up a bit. I am not going to go into it right now. I will be keeping my eye on it. If I need to change things I will post a little later today. Otherwise, my next update will be Wednesday morning.

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