Wednesday 10/20  6:30 am

The models are continuing to show a series of large storms hitting the Pacific Coast over the next week. Initially, these storms will trigger scattered showers from Washington down to Northern California beginning today. The largest of these storms will drop further south starting Sunday and deposit heavy rain and snow across Central California and the Sierra.

The good news is this will end the wildfire season. It will also be a huge boost to the reservoirs around the state. The bad news, mudslides across the fresh burn scars. Some of the people I follow out there are saying this could be a historic event and break the October 2004 record of 85.6 inches of snow for Mammoth Mountain.

If you missed my post yesterday, these types of events don’t translate to heavy precipitation for us. That being said we usually fare slightly better than the latest model runs are showing.

Here are the latest precipitation forecasts for the western US.

Euro

GFS

Canadian

Here are the state views

Euro

GFS

Canadian

If you remember the Canadian run from yesterday it was much different.

Canadian 24 hours ago

That is a good example of the model run roller coaster we will be on over the coming days.

When there is this much model uncertainty I am drawn to the more practical weather approach of looking at the ensemble families of the underlying models.  These models take the average of all of the model members that make up the model family. I rely on them more several days before a storm. The good news or bad news with the ensembles is that they do not fluctuate as much on a run-to-run basis.  I usually switch back over to the deterministic (single model) runs a couple of days before the storm arrives.

Here are the latest ensemble model precipitation totals

Euro

GFS

Canadian

There is one other trend I am seeing. The models are starting to introduce some light showers over northern portions of the forecast area on Sunday. So far they look insignificant. We’ll see.

 

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10/19 Tuesday 9 am

Last night’s light precipitation event has come to an end in most areas. Isolated showers may linger a while in the Northern San Juans and over Wolf Creek.

AR events, also known as an Atmospheric River have become an overused term that the weather media has become obsessed with over the last few years. It is right up there with the dreaded Polar Vortex. Both are coming but one will be sooner than the other.

For those of you old enough to have gray hair, we used to know Atmospheric Rivers by the name of The Pineapple Express. This is not to be confused with the bad movie of the same name.

Over the last few days, I talked about the MJO going into phase 1 after the 24th. I also said I would talk more about the MJO, which I will, but not right now. The result of the MJO in phase 1 translates to cooler, wetter conditions for us.

The models are still struggling with exactly where the MJO is going to end up. The GFS has transitioned towards phase 1 over the last couple of days, now this morning it is backing off slightly. There is only one model showing the MJO going deep into phase 1.

The Euro has backed off from where it was a couple of days ago but seems to at least make it there. The Canadian model is similar to the Euro, stalling around phase 1.

The Japanese model is showing a deep trek into phase one. The deeper the model goes into a particular phase the higher the confidence in the resultant conditions for the phase. The Japanese model is a highly regarded model, especially for long-term seasonal modeling and for ENSO (El Nino/La Nina).

My problem with AR events is the majority of the time they do not live up to the hype. They run out of most of the precipitation before they get here.

Here is the Euro in motion.

This is the regional view, I am going to stop it right as it reaches Colorado.

Check out the precipitation accumulation for California.

That is 6 to 12 inches of liquid across the Sierra.

How about snow?

It is difficult to see but that is 40 to 80 inches of wet snow in the higher elevations.

OK, back to our area.

I am going to use static images otherwise it goes too fast.

Tuesday morning the moisture arrives.

Tuesday at noon!

Tuesday 6 pm…

12 am Wednesday morning.

Wednesday morning 6 am.

Euro precipitation total

Euro snow

BOOOOOOOOO!

That was a very extreme example of what I don’t like about AR events.  I do not think it would be possible for that strong of an event to end up like that for Western Colorado. However, that is what it sometimes feels like around here. Here is a look at the other models. I will spare you the run-up and drama and just cut to the totals.

GFS

Canadian

I think the Canadian is the most believable of the three.

I know I mentioned the Polar Vortex earlier. That won’t be for a while, and it is way too early to figure out where it is going to end up over North America. Historically, if it is going to affect our region, it drops into the Upper Great Lakes or Upper Midwest then retrogrades west spilling colder air into our area.

 

I will be tracking this all week, next update Wednesday. Thanks for following and supporting the site!

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10/18 Monday 1:30 pm

The latest model runs are indicating that we will see light snow stretching from NW to SE from Telluride to Wolf Creek Pass. Amounts will remain light (1 to 4 inches). Models are now in agreement that the precipitation will start around midnight. It would not surprise me to see an inch or so around Purgatory. The snow level may drop to 8,200 feet. This could lead to what we call “normal winter driving conditions” especially over the passes.

I hate to say I am going to cover something in my next update then not do it. Unfortunately, I am going to delay my discussion on the potential for a pattern change until tomorrow morning. After complaining about the models being out of sync this morning, they all came together for the most part for tonight. That led me down a different rabbit hole and I did not have a proper amount of time to put into next week. I will cover that Tuesday morning.

My next update should be out around 9:30 Tuesday morning. Thanks for following and supporting the site!

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10/18 Monday 9 am

For numerous reasons, I have low confidence in this forecast. The models had all come together showing a wave associated with the low-pressure system rotating into the southern forecast area this morning. That has not happened yet. The short-term high-resolution NAM 3km model that just came out is showing that happening now. I see no signs of it on radar, webcams, or the latest surface maps.

The cold front and closed low-pressure are currently over central Nevada this morning. Snow and rain showers are breaking out in advance of the front and behind, all of the way back to the eastern side of the Sierra.

The front and low will continue east through Utah today and reach Colorado late tonight. Only the southern tail of the system will be available to affect our weather. This northerly storm track is more common than not this time of year.

The models have never portrayed this as a big weather maker for us. At best, some of the higher elevation areas generally above 9,000 may get a couple of inches of snow. Telluride and Red Mountain stand the best chances of seeing this snow. To put this system in perspective, it looks like a lower producer than the last one.

The models are in worse agreement today than they were yesterday. I don’t know how much time I want to devote to this system. My focus will shift towards what looks like a pattern change in the next 7 to 10 days. I will talk more about that this afternoon.

My next update should be out around 2 pm today. Thanks for following and supporting the site!

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10/17 Sunday 7 am

Overnight, the models continued the trend of dropping the storm track a little further south. This increases my confidence that northern portions of the forecast area are going to get a couple of inches of snow late Monday into Tuesday. Not a big deal, but fun for fall. For everyone else, just a dusting or few drops if anything at all Monday night into Tuesday.

The other thing that I am getting confident about is a very small nuisance system that will rotate out of the main low to the west around or after 3 am Monday morning. If this happens, it will affect mainly the southern and central portions of the forecast area. If you are going to be driving in those areas early tomorrow morning you could run into some wet to slick conditions, with an inch or so of snow near the top of Wolf Creek Pass and Coal Bank Pass.

This reminds me, I have picked up a lot of followers in the last 10 days who may not know what the forecast area is. From south to north it extends from Aztec, New Mexico to Ridgway, Colorado. It includes Telluride, but not Lake City. From west to east it extends from Cortez, Colorado to Wolf Creek Ski Resort. I don’t choose these areas because they are my favorites. I chose them because I am more familiar with how our weather interacts with the topography.

Southern portions of the forecast area include everything south of Cortez, Mancos, Durango, Hermosa Bayfield, Trew Creek, Pagosa Springs, Wolf Creek.

Central portions of the forecast area include everything north of Dolores, Rico, Glacier Club, Lemon, and Vallecito. It extends north to Molas Pass.

Northern portions of the forecast area include Silverton, Telluride, Dove Creek, Ouray, and Ridgway.

Here are the maps in motion. Notice right out of the chute the Canadian and Euro pick up on that small disturbance early Monday morning. The models may be overdoing the effects west of Archuleta County. We’ll see.

Canadian

Euro

GFS-nothing Monday morning

Here are the totals

Canadian-this looks reasonable.

Euro-this does not make a lot of sense.

GFS-If I could overlay the GFS on top of the Euro it would look the best of all of the models.

German-This looks interesting as well.

I still have my eye on the last 7 days of the month as a time period of interest. The GFS is starting to come around. Of course, now the Euro is backing off a bit. It will be a long roller coaster ride for the next several days. I will be focusing on it all week.

Two updates on Monday, the first will be out by 9 am. The second will be out by 4 pm. Thanks for following and supporting the site!

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Saturday 10/16 12:30 pm

Things will be quiet and tranquil until at least Monday morning. I have mentioned a couple of times that the European model has been advertising a small disturbance rolling up from the south.  The Euro, Canadian, and the US NAM models are now all picking up on this. This should not be a big deal but may affect some of the higher peaks in NE La Plata County over to Wolf Creek Pass. At the moment, it looks pretty harmless.

The other development is that all models are trending deeper, colder, and further south with the next system due to affect western Colorado later on Monday. It does not look like a significant precipitation producer but it is looking more likely that the northern portion of our forecast area may see some more snow.

After that, it still looks like we will be going through a boring stretch of weather until around or after the 24th.

Sunday morning I will dig a little deeper into the Monday evening storm, stay tuned. Thanks for following and supporting the site!

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Friday 10/15 8:45 am

Low temperatures are the big story this morning. Overnight low temperatures ranged from 20 to 25 in the lower elevations. Most mid-elevation areas were hovering around 20 degrees. Higher elevations ranged from 10 to 18 degrees.

Yesterday afternoon, as expected, a few snow squalls came through areas north of 160 resulting in light accumulations and even a little convection. Here was what it looked like near Glacier yesterday afternoon around 4 pm.

I did not hear from any followers in the northern portion of the forecast area, but it looks like Telluride picked up close to 4 more inches on their snow stake. Here is how that looks this morning.

This weekend we will have nice fall weather. Temperatures will rebound slightly with seasonal overnight lows and high temperatures running slightly below average.

The models are still out of phase for next week and beyond. The Euro is trying to bring in a small disturbance from the south Monday morning. The other models are not seeing it yet. They are in better agreement with a disorganized system entering the north half of the state on Tuesday. There is not a lot of run-to-run consistency on the placement of that system.

It looks like things will settle down for a few days after that. Around the 23rd things could get interesting. I mentioned the MJO forecast from the European model the other day. The model is still showing the MJO entering phase one. The operational model is responding right on cue by showing a large wet system entering the west. The GFS is not showing this. Until there is better model agreement I don’t want to get too deep into the weeds with that one. However, here is a glimpse of what the models are showing for day 10 (10/24).

Euro

Canadian

GFS (what storm?)

Stay tuned…

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10/14 Thursday 8:50 am

Since my last post, the models have taken a slightly more southerly track with the short wave trough which is currently stretched from southeast Utah into west-central Colorado. It is draped across the Grand Junction area.

I circled it in black.

It will be moving east throughout the day and will bring 2 to 8 inches of snow across northern portions of the forecast area. There may be some upside surprises up to a foot between Ouray and Red Mountain. Silverton ski area could also do well.  Telluride and Silverton (town) will likely see 2 to 5 inches of snow.

There is a lot of uncertainty about the track this disturbance will take. There is not a lot of moisture with it, but as I said there will be some surprises.

If the system drops a little further south, odds are that more of the southern portions of the forecast area will be affected. I would be very surprised if anyone south of 160 will be affected. I do not expect accumulations here, but some brief snow squalls may accompany the passage of the disturbance. We have seen those happen before. You go from cloudy to what looks like a blizzard for 5 minutes, then the sun comes out.

The models have struggled with overnight low temperatures all week. Today is no exception, some models are calling for the coldest overnight lows of the season by tomorrow morning. We’ll see.

There is no agreement whatsoever among the models for what will happen Monday through Wednesday of next week. I will be tracking that and posting a closer look at those scenarios starting Friday morning.

I look forward to hearing reports of heavy snow or snow squalls passing through. Thanks for following and supporting the site!

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10/13 Wednesday 9:30 am

Thanks for all of the reports yesterday, last night, and this morning. There were so many I could not respond to every one of them. If someone is asking me a direct question I try to respond. In some cases when my inbox is backed up I may not be able to respond immediately.

There does seem to be a lot of excitement about winter. I still don’t feel strongly one way or another yet. I follow a lot of people in the industry way smarter than me. I have not yet read a compelling enough case either way for the winter for me to jump on board. As I mentioned a couple of weeks ago, I would not be dismissing this winter by any means.

A smaller, dryer, and colder system will move from north to south down the western slope on Thursday. This system will favor northern portions of the forecast area with 3 to 8 inches of snow. I expect 3 to 5 inches will be more common. Areas around Purgatory and Mayday may see a couple of snow squalls but I do not expect accumulations greater than a heavy dusting.

After Thursday we should see the sun come out and a nice, cool, fall weekend will take over for the entire forecast area. The models are struggling with the progression of another system or two during the first half of next week. I think these systems will stay too far north to affect us. However, I have seen a couple of model runs in the last couple of days showing some snow and rain across northern portions of the forecast area. We have some time to figure all of that out.

After that, the next possibility for another storm looks like it would be after the 24th.  At that point, the MJO is forecast to go into phase one. I will talk about the MJO as we get closer to winter. I will refresh the long-time followers and help the new followers understand it.  Some of you that have been following me for a while may remember that the MJO in fall and winter means a cool and wet period for us. It usually means conditions are favorable for the development of a winter storm.

My next update will be Thursday morning. Thanks for following and supporting the site!

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Tuesday 10/12 1:50 pm

As is often the case, there were many discrepancies among surface map providers this morning. It turned out Wunderground had the best placement for the cold front and the parent low. The cold front finally made it into Colorado around 9 am. The parent low is still spinning over southern Utah. WPC had indicated that the cold front passed Durango at 6 am. In actuality, that was a short wave trough ahead of the cold front. I was in Durango at 10:30 this morning when I saw the updated surface map from Wunderground. I emailed it to myself so I could share it with you this afternoon.

The blue line with triangles is the cold front. The southern portion is leaning back (negative tilted), which means it is strengthening. The blue and red line extending out of the cold front is indicating that a portion of the front is stalled. It is leaning forward (positively tilted) which means it is weakening. All of the dotted brown lines are shortwave troughs, most have their own area of low pressure associated with them. This is definitely a complex system.

Most mid-elevation areas below 8,000 feet have not received significant accumulating snow. It has been too warm in the lower elevations for much more than rain. I have not received many snow reports. The last report I got from Silverton was 10″ at 10 am. I also got an earlier report of 7″ at Mountain Village. The automated PWS (personal weather stations) don’t show snow, so I rely 100% on the public for snow reports.

Here is the latest surface map from WU.

I tried to extrapolate the low location from the near-live satellite view.

It is pretty similar to Wunderground.

Where that slow-moving parent low tracks from here will determine who (if anyone) gets snow tonight. As it passes winds will be more favorable for the northern portions of the forecast area. If the low tracks a little further east, precipitation will continue or redevelop over southern portions of the forecast area. Models are notoriously horrible at predicting this. So, we will have to wait and see.

 

Thanks for the reports. Next update Wednesday morning, thanks for following and supporting the site!

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