I confess that I feel somewhat conflicted right now. The backcountry riding has been really great since the last storm and it's a bit of a shame that we're going to submerge those sublime crystals with what is coming over the next few days. Ideally we would have another day or two before another goldilocks storm, but instead we have a monster on the doorstep.
The models continue to put out big numbers for this storm. Our downscaled NAEFS product is putting 4 to 10 inches of water for Alta Collins through 12Z January 2nd (5 AM MST Monday), with an average of about 7 inches of water. Note that today is just a minor appetizer. Things pick up this evening and then continue for about 60 hours. There could be a break or two in there, but expect big numbers.
The high resolution HRRR is also going off. The forecast below covers the period from 1800 UTC 30 December (11 AM Friday) through 1800 UTC 1 January (11 AM Sunday) and puts out 6+" of water for Timp, 5.8" for Alta, and 5+" for Ben Lomond and Powder Mountain.
We've created a new HRRR-derived product for Little Cottonwood (available at
https://www.inscc.utah.edu/~steenburgh/ml/hrrr_lccforecast.html) the version derived from the HRRR run above shows a predominantly warm 48-hour period through Sunday morning with Mt. Baldy temps warming tonight to near or above 20ºF where they remain for the forecast period. The wet-bulb zero levels is near 8000 feet for a good chunk of the period.
This means snow levels will rise today and tonight to perhaps 6500-7000 ft, with high-density snow at upper elevations. I'm not sure the snow-to-liquid ratios will be as low as 5 at times, as suggested above, but I do expect this to be a high-density storm.
The GFS is a low-end model. The forecast below is from the a run initialized 6 hours before the HRRR forecast above, so it only goes through Sunday morning, but it similarly shows Mt. Baldy temps clibing to near 20˚F by this evening and periods where the wet-bulb zero level is 7500 feet or higher.
The Euro is often a bit drier and for Alta is a bit under 3" for a storm total, although a gird point farther south is at about 3.77".
The NWS cottonwoods forecast is due for an update as I write this. The one from last night is below and calls for a storm total of 3.5-5.5" of water and 36-56" of snow.
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| Source: NWS |
I don't see any reason to question those numbers, and it is important to circle the wagons at times like these and tell a consistent story, so I'll stick with them.
Bottom line: Buckle up.
One of the many nice aspects of retirement is there is plenty of time to let go of conflict by lounging at home commenting on blog posts during warm New Years eve atmospheric rivers. And Saturday has become a designated rest day, except for exceptions such as cold storms. Also, at the risk of oversharing, I have a bunion on my left foot from 57 days of touring for vertical gain of 230,000 feet since Oct 23 in marginally too tight Backland’s and new too thick socks. (In terms of high quality life experience the past few weeks have had a record number of OMG powder days, explaining my absence from the Weenie comment section.) Removing the lower buckle, returning to old thin socks, and a bit more rest seem to be the cure. One of the drawbacks of retirement is because you are not young if you try to behave like you are young your body will smack you down.
ReplyDeleteHave you heard about the NEW expanded enhanced PRAYER.
We MUST PRAY for MORE SNOW, LESS WIND and LOWER WETBULBERO with VERY MANY ICE NUCLEATING PARTICLES.
Judging by UDOT cameras and Collins snowstake, looks like a good day to be touring above 9000 feet in low angle terrain well away from historic avalanche paths. Southfacing Willows come to mind. Alas, Mill Creek, Neffs and Lambs do not fit the bill. Ergo rest.
Two questions.
1.Any thoughts on this season’s storm track beyond some years the storms track straight to Alta and some years they don’t but Alta always gets more than Mt. Mansfield except for 2014-15. Seems like the resilient ridge off California is usually the culprit in low snow years and splitting storms. Something unusual this year removing the ridge. Some other reason for the superb storm track.
2.You are and presumably remain impeccably correct in refusing to attribute single events such as rain at Alta base on New Years eve to climate change. And warm atmospheric rivers have always been a thing. Do you think there is a trend toward warmer events with DASTARDLY higher wetbulbzero. Assume everything constant except atmospheric CO2 at 320 in 1960 compared to 420 in 2023, would todays AR have rain/snow at 5000 as compared to 8500 this morning. Your unguarded speculation is encouraged. Any nuance on climate change reducing ice nucleating particles … seemed like an interesting thing to say.
In conclusion and to REPEAT
NOW!!! is the time to PRAY for MORE SNOW!!, LESS WIND and LOWER WETBULBERO!!! with VERY MANY ICE NUCLEATING PARTICLES.
And I see LCC is closed for avalanche control. Aside from the fact the trailhead is basically in a historic path, White Pine offers a miserable start on a day like today and no real safe ski terrain above 9000 feet. Grizzly Gulch is a possibility but expert level terrain management is required. The problem with LCC is you never know if mid-day avy control will be necessary with resulting slides closing the road for days on end.
DeleteYes, low angle southfacing BCC is the only real alternative on days like today. USA Bowl is 34 degrees at its steepest location. It has never slid but climate change may afford new opportunities for unusal avalanches
Concerning ice nucleating particles, you'll be glad to know that Cottonwood weir was running their silver iodide generator this morning, not that it will do any good in this storm because cloud top temperatures are high and cold enough that such seeding is a waste.
DeleteA greater fraction of winter precipitation is falling as rain instead of snow. I think the elevations of statistically significant trends is at or below 8000 or 7000 feet. I'm going off the top of my head on this.
Get well. I haven't seen you in Mill Creek this week and I made a couple of appearances there.
Jim, random observation. Sure snow settles but how on earth have we had 46" at Alta since you officially declared Steenberg winter on Dec 15th yet the official Collins depth remains just below 100"?
ReplyDelete