Colorado Weather Discussion Thread

[The_Lorax]

Really? was that last night?


I'm in Snowmass right now about to head back to FoCo.

This is the NOAA forcast for Snowmass Village:
Tonight: A 40 percent chance of snow. Cloudy, with a low around 6. Southwest wind around 15 mph, with gusts as high as 35 mph.

Monday: Snow and areas of blowing snow. High near 21. Breezy, with a southwest wind between 15 and 20 mph, with gusts as high as 40 mph. Chance of precipitation is 80%. New snow accumulation of 6 to 10 inches possible.

Monday Night: Snow and areas of blowing snow. Low around 18. Breezy, with a south southwest wind between 15 and 20 mph, with gusts as high as 35 mph. Chance of precipitation is 80%. New snow accumulation of 5 to 9 inches possible.

Tuesday: Snow and areas of blowing snow. The snow could be heavy at times. High near 18. Breezy, with a south wind 20 to 25 mph becoming west. Winds could gust as high as 50 mph. Chance of precipitation is 80%.

Tuesday Night: Snow likely. Cloudy, with a low around 0. Chance of precipitation is 70%.

Wednesday: Snow likely. Cloudy, with a high near 18. Chance of precipitation is 60%.




I'm pissed I have to go back today for dead week/finals!

[The_Lorax]

Frustrating again, I got 5 inches in my yard in Fort Collins and I see Breck/Key/Basin/Loveland all got zip. BS I tell you.

my bad, the "really, was that last night" was supposed to be quoting you....

[DaHeel]

Let's hope the Monday storm produces as forecasted. Fingers crossed

[Puffin]

Vail has gotten literally no snow accumulationlast night or today...

[The_Lorax]

Vail has gotten literally no snow accumulationlast night or today...

I woke up this morning at Snowmass and there was only about 2" on my car, it stopped snowing entirely about an hour ago and there's not much wind right now but I can see the clouds coming in again. This feels so wierd to say but I hope the storm doesn't come in until after I leave to drive Vail Pass.

[Spyplane]

my bad, the "really, was that last night" was supposed to be quoting you....

Yeah, we're up to 6" plus in west Fort Collins. Lame... snow needs to get its ass up to the mountains!

[funkendrenchman]

Predictions are getting smaller and smaller for our area.... was 1-2 feet, then 10-20", now 8-16". We really need a big storm!

[gratzo]

Was up at Polar Star Hut Saturday night (near New York Mountain, about 7 miles WSW from Beaver Creek as the crow flies). About 2-4" fell up there, but the storm seemed to lack a few ingredients (jet stream support, moisture) as the flakes were more like tiny, minuscule balls. Somehow, Wolf Creek, Durango, and Silverton picked up 5-10" last night...very strange.

Even though this (Sunday's) storm was a dud for areas along I-70, most other areas received at least a few inches.

The Monday/Tuesday storm still looks like the real deal, though, especially for the south and east San Juans (Durango, Silverton, Wolf Creek) with 20-40" a good bet. The models are showing anywhere from 2-3" of liquid, and with temps around 10,000ft at 15-25F, the snow ratio will be somewhere around 10-12 inches of snow to each inch of liquid. Of course, Wolf Creek will probably report 60" (not saying they lie...just saying strong southwestern storms can dump much more precip than the models think).

CB and Aspen should also do well...maybe 10-20" if things go well.

Areas north and east of Aspen (I-70 resorts) will be jealous and basically snowless (a few scattered, light inches?) until Tuesday afternoon, when they should get a few quick inches (best shot around BC/Vail and Steamboat with 6") as the storm passes and the winds shift from the northwest.

With storms coming from the southwest, I've been disappointed too many times with good totals predicted for the I-70 resorts, but little actual snow falling. That's why I'm hesitant to predict more than a few inches for this area until Tuesday PM when the storm moves across the state and the winds go northwesterly.

Models are indicating a decently moist flow from the northwest on Tues afternoon through Thurs AM, which could add a few more inches to the I-70 and north resorts (again, best shot around BC/Vail and Steamboat with 6" more if lucky). Backcountry areas along the northern divide could also do well in this pattern.

Driving through the Vail valley and Summit Co. just now, it was tough to see how little snow there was, especially since the snow in Boulder just keeps piling up.

[Rontele]

Predictions are getting smaller and smaller for our area.... was 1-2 feet, then 10-20", now 8-16". We really need a big storm!

I still think this will be a decent event given the tremendous dynamics which will help overcome the crappy orographic flow.

[Rontele]

Not to be a douche but where do you see them backing off?

My math adds to 3.5'+ even with their conservative estimates?

Tonight: Snow, mainly after 5am. Low around 2. Wind chill values between -15 and -25. Windy, with a west southwest wind 20 to 25 mph increasing to between 30 and 35 mph. Winds could gust as high as 45 mph. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible.

Monday: Snow and widespread blowing snow. The snow could be heavy at times. High near 13. Wind chill values between -15 and -25. Windy, with a southwest wind between 25 and 35 mph, with gusts as high as 50 mph. Chance of precipitation is 90%. New snow accumulation of 11 to 17 inches possible.

Monday Night: Snow and widespread blowing snow. The snow could be heavy at times. Low around 8. Wind chill values between -10 and -15. Very windy, with a southwest wind between 30 and 40 mph, with gusts as high as 55 mph. Chance of precipitation is 100%. New snow accumulation of 20 to 26 inches possible.

Tuesday: Snow and widespread blowing snow. The snow could be heavy at times. High near 14. Windy, with a west southwest wind around 30 mph, with gusts as high as 50 mph. Chance of precipitation is 90%. New snow accumulation of 9 to 13 inches possible.

I think he is saying they have been backing off the amounts for the Central and northern mountains - say Aspen north...

[Rontele]

Predictions are getting smaller and smaller for our area.... was 1-2 feet, then 10-20", now 8-16". We really need a big storm!

I also wouldn't get too down as the ever accurate fireweather point forecast still has a foot of snow by tuesday morning before the even switches to your mountains.

[montanaskier]

today didn't do much for this zone. Basically nothing in town at all. A couple inches on the hill I think. Agree with Gratzo that the Vail area will probably see nothing until Tuesday. I would expect 6-8" at the most. Something but not the big snow we need. Hope the San Juans go off.

Maybe an active pattern starting. Fingers Crossed.

[gratzo]

I still think this will be a decent event given the tremendous dynamics which will help overcome the crappy orographic flow.

Orographic flow is king, and the models don't give it enough significance. This goes both ways. The San Juans are likely to get more than the 2-3" liquid equivalent that the models predict, mostly because of the "X" factor of orographics. I wouldn't be surprised to see 4-5" of liquid and 40-60" of snow for the winner in the San Juans (likely Silverton and Wolf Creek).

On the flip side, areas north of Aspen just won't do well due to the orographics (downsloping). The models are keying on the intense dynamics of the storm, but the negative orographics can overrule even the best dynamics. I have no research study to back this up, but I do have experience of being super excited for deep snow around Vail from SW storms, and this snow not materializing until after the flow swung around to the northwest. I really do not see areas north of Aspen doing well until midday(ish) Tuesday as the storm moves across and the wind changes. It might not even be until late Tuesday, since the storm might be a bit stronger and slower than the models anticipate.

On the plus side for areas north of Aspen, there looks like a 1-2 day stretch of on-and-off northwest, moist flow that could put down 6-12" between Tuesday night and Thursday morning for Vail/Beaver Creek and Steamboat. Somewhat less for Summit Co. and the divide.

The National Weather Service has been backing off snow totals north of Aspen until about late Tuesday (and rightly so). Not to be a downer, but I just don't think it's gonna fly.

On the up side, if you want to see a blizzard with 3"/hr snow and 30-50mph winds, head to Wolf Creek Pass on Monday night. I bet Wolf Creek Pass and U.S. 550 will both be closed from Monday afternoon through Tuesday night. Monarch pass might be on the fence for a few hours Monday night/Tuesday morning.

[gratzo]

I also wouldn't get too down as the ever accurate fireweather point forecast still has a foot of snow by tuesday morning before the even switches to your mountains.

Even for Fireweather, I think it's overdone north of Aspen before Tuesday midday. Not trying to be a hater, just trying to be realistic. It might indeed snow north of Aspen on Monday, Monday night, and Tuesday morning, but it just won't amount to much. I still have great faith in the models, but when the models disappoint me (i.e. I get less snow than is predicted), I tweak my view.

Let. It. Snow!

[Rontele]

I agree with everything you say, G. All I am pointing out is that I don't think anyone can tell me the last time a 987mb low crossed this state. That is just a lot of dynamics to play the "orographics only" card.

The reason the San Juans are going to get pummeled is because of orographics combined with what can only be categorized as a cyclone. This cyclone will help overcome the limiting poor orographic flow for the other areas and is why I am still a bit more upbeat.

[Rontele]

and I'll add that I think 8-16 for those mountains is a decently accurate forecast.

[adam]

This storm will fizzle.

[skiracer88_00]

This storm will fizzle.

it doesn't snow in colorado

[gratzo]

I agree with everything you say, G. All I am pointing out is that I don't think anyone can tell me the last time a 987mb low crossed this state. That is just a lot of dynamics to play the "orographics only" card.

[sorry for the weather geek terms...]

Very true! I just don't want to hang my hat on the added convergence associated with the cyclone center, as the center is notoriously hard to pinpoint, even 12-24 hours out. Looking at the last three major runs of the NAM (00z Mon, 12z Sun, 00z Sun), the position of the jet streak stayed about the same, but the center of the low moved further north with each run. Maybe it's a trend, or maybe the model is just having a hard time with the position of the low. Who knows!

With such a strong jet streak moving through the base of the trough, I wouldn't be surprise to see the cyclone center a little further south and east of the current model's position.

Wherever the low moves across the state, there will definitely be heavier precip...but in a sense it will be hit or miss precip if the low moves across an area with otherwise unfavorable orographics. Would love for this to be the I-70 zone to "even out" the snowfall across the state, but am just not holding out hope right now.

This is going to be fun!

[Jay P]

looking at all the cdot cams right now I am pretty disappointed, doesn't even look like they got 6 inches

http://www.cotrip.org/device.htm

[Rontele]

looking at all the cdot cams right now I am pretty disappointed, doesn't even look like they got 6 inches

http://www.cotrip.org/device.htm

The storm hasn't started jong.

[Rontele]

[sorry for the weather geek terms...]

Very true! I just don't want to hang my hat on the added convergence associated with the cyclone center, as the center is notoriously hard to pinpoint, even 12-24 hours out. Looking at the last three major runs of the NAM (00z Mon, 12z Sun, 00z Sun), the position of the jet streak stayed about the same, but the center of the low moved further north with each run. Maybe it's a trend, or maybe the model is just having a hard time with the position of the low. Who knows!

With such a strong jet streak moving through the base of the trough, I wouldn't be surprise to see the cyclone center a little further south and east of the current model's position.

Wherever the low moves across the state, there will definitely be heavier precip...but in a sense it will be hit or miss precip if the low moves across an area with otherwise unfavorable orographics. Would love for this to be the I-70 zone to "even out" the snowfall across the state, but am just not holding out hope right now.

This is going to be fun!

And I do not think for a minute the snow totals will be anything equal. The San Juans will come away with likely 40+ inches of snow in spot. I think the 8-16 forecasted for the northern and central mountains is reasonable.

[Gregger]

The NOAA discussion has mention of good orographics coming inline for the I-70 corridor late tonight and Tues/Weds. New model runs are much more positive than yesterday. Even the urban corridor is looking at 1-2" today, 3-7" tonight and 3-6" tomorrow. And that's with fairly shallow upslope.


And for your ratio discussion. At 15-20 degrees, the snow ratios will be WAY higher than 10 or 12:1. Try 15 or 20:1. I think this week will make up for a shitty November, and the NW flow that'll be kicking in hard (according to the models) at the end of the week should bring more snow for next weekend.

[gratzo]

The NOAA discussion has mention of good orographics coming inline for the I-70 corridor late tonight and Tues/Weds. New model runs are much more positive than yesterday. Even the urban corridor is looking at 1-2" today, 3-7" tonight and 3-6" tomorrow. And that's with fairly shallow upslope.

And for your ratio discussion. At 15-20 degrees, the snow ratios will be WAY higher than 10 or 12:1. Try 15 or 20:1. I think this week will make up for a shitty November, and the NW flow that'll be kicking in hard (according to the models) at the end of the week should bring more snow for next weekend.

I don't see good orographics coming in line for I-70 corridor until after the trough axis passes around noon on Tuesday. Maybe I'm missing something, though. Good orographics for I-70 corridor are 700mb winds from a west to northwest direction.

As for ratios, the temps may be a bit misleading. With tons of Pacific moisture coming in, I can't image ratios much better than 12:1 in the San Juans. 20:1 is usually reserved for storms with lower moisture content coming from the west or northwest. 20:1 is true "fluff" where you can blow away 3-5". This storm will not produce fluff in the San Juans.

The urban corridor does have better orographics with an easterly component to the wind, and the amounts of snow are decent only because the air is VERY cold, so just a little bit of moisture can eek out a few inches of snow.

We'll see...Wolf Creek Pass CDOT cam finally showing some good snow.

[raymonster]

This storm will fizzle.

Its fizzling pretty hard in CB right now. Small flakes but coming down at a good clip. Supposed to ramp up around mid-day, heaviest snow tonight.