True Winter . . . ?

Sunday, October 14, 2012 at 7:48 pm

Thursday AM update:

Not too much to update today.  Warm temps until late Sunday when a cold front will drop into the area and stall out over northern Utah.  Valley rain and mountain snow possible with initial front on Sunday night and Monday.  Tuesday looks to be a bit of a break before the main low starts to affect the area late on Wednesday.  Confidence is low, so for now we are just going to broad brush the whole of next week with the tag of ‘unsettled’ and wait another day or two for models to figure everything out before we start talking exact timing, snow levels, snow amounts.  Stay tuned . . .





Wednesday AM update:

The last few days have been hectic from a forecasting point of view because all global models were struggling with the potential pattern change mentioned in our previous discussions. It seemed as if not only each model, but each model run, offered a different solution for the evolution of the large scale pattern.  For now, the models have come into better agreement and have had at least two runs each to reflect this consistency.  So we feel like we’re standing on somewhat solid ground forecasting rather than the quicksand that was yesterday’s post.  What we see is that heights will build over the area over the next few days, allowing for a quick warm up from yesterday’s cold front– with dry conditions through the weekend.  This weekend, however, a low will drop down off the BC coast.  The low will split with the first part of the low ejecting inland across the Northern Rockies.  The other, stronger split of low pressure system, will remain off the coast.  Models show this low stalling off the Pac NW coast.  The cyclonic flow around the low will force impulses into the west coast.  The GFS shows this low spending at least 48 hours spinning off the coast sending impulses into Oregon and Northern California.  Models show the persistent, moist flow crossing northern Nevada into Northern Utah.  However, the farther from the parent low we are, the less moisture we are likely to see.  But even still, orographic lift and duration of precip event could bring us substantial snowfall nonetheless.  This pattern doesn’t look nearly as cold as the one the EC was portraying the other day, so snow levels will likely be well above SLC valley floors.

After about Wednesday of next week, it’s difficult to know exactly what will happen as it is totally dependent on the track the low takes once it finally get kicked inland.  Of course, even this moist flow forecasted by models right now for early next week is very low confidence for two reasons.  One, we are still far out from the event and model consistency as been poor (to say the least) over the last few days.  Two, even if this pattern verifies, this is the type of scenario that is very much dependent on the exact positioning of the low off the coast.  So small changes in track can mean big changes in snowfall.  At this time, WSF feels confident in saying that we will at least be unsettled next week with some snow falling.  And there is potential for our first significant winter storm of the season, it all depends on how this evolves over the next few days. So stay tuned . . . Fingers crossed!


Previous . . .

Tuesday AM update:

Everything on track for system to clip area this afternoon.  Details for which are below.  Then ridge builds in for warmer temps this weekend.  Next week is a big question mark.  It looks like it will be unsettled to some degree.  But there are so many discrepancies between models that it’s impossible to know what to forecast.  At this time it seems like the cold, snowy pattern may be less likely, unfortunately.  We’ll keep watching and see if there is some kind of agreement later today.

Monday PM update:

Tomorrow afternoon’s system will clip Northern Utah, bringing a chance for light showers. Main impact will be the first major wind event of the season along and just behind the front. Might be time to put away the lawn furniture before it blows away! Since the bulk of cool air will stay to our north, we expect only a dusting
of snow above 9,000 ft or so tomorrow evening with the front passage. Areas farther north, including Powder Mountain and Snowbasin and along the Idaho border stand the best chance to see accumulating snow, but at best, it will only be an inch or two. Cool temperatures will be left in the front’s wake on Wednesday.
Ridging will rebuild as we head toward the weekend with rapidly warming temps.

Potential pattern change mentioned in yesterday’s discussion (below) is still in the cards in most models. Main difference between models is how far south main trough digs early next week. GFS keeps the best precip and cold air to our north while the GEM and EC both bring significant cold air and moisture into Utah. Right now, we are leaning towards the colder, wetter solution. 18z GFS seems to reflect this as it trended slightly farther south than previous runs. Of note, if the colder solution verifies, we could be looking at snow down to SLC valley floors–lake effect snow is also a distinct possibility as GSL surface temps are still relatively warm. Still very early but this is an exciting trend that could go a long way to getting us all on the mountain. Cross your fingers that the models don’t backtrack.



Back from vacation, which means it’s time to start checking the models and the teleconnections obsessively again to look for signs of our next snowstorm.  While out-of-state, I was fortunate to provide at least quick updates for this last Friday’s system.  Which from everything I can tell, seems to have put down a few inches in the high Wasatch as expected with greater amounts in Southern Utah and the Uintas.  We mentioned before that it was unlikely that the system would be anything more than a teaser as most, if not all, of the snow that fell  would melt away within a few days.  That seems to be the case as webcams suggest most of it is already gone through a combination of seasonally warm temps, sunshine, and warm ground temperatures.  So when will “true winter” arrive with snow that’s substantial enough to stick around? Maybe next week–more on that in a minute.

If you’ll recall, last week we mentioned a system that would be affecting the Pacific Northwest early this week and had potential to clip the area according to the GFS.  Well it seems that the GFS was spot on and the ECMWF (Euro) has latched onto this same idea.  What that means for N. Utah is an increase in clouds and breezes Tuesday morning with a chance for showers during the afternoon and evening hours.  Unlike last week’s system, this next one will favor areas to the north, so Snowbasin and Powder Mountain will have their turn to have a teaser.  At this time, we don’t expect anything more than a dusting south of I-80 with a few inches possible above 8,000 ft. to the north of I-80.  The system will drop down to our east and could again give the Uintas and Colorado Rockies a more decent snowfall.  The main impact for most of Utah will be to cool temps back down below normal again for at least a day or two on Wednesday/Thursday.  Temps will rebound as we head toward the weekend ahead of the next, potentially more vigorous, system.

After not checking the models for the last 48 hours due to a combination of travel and leisure, I was excited to see that the latest 18z run of the GFS and the latest run of the Euro both show a potential major pattern shift for next week.  These solutions were suggested in long range “fantasy” charts last week–I mentioned the CFSv2 was depicting a potential unsettled pattern developing for the last week of October.  We generally take these long range models with a grain of salt as anything beyond 10 days is very unreliable, but it was worth noting.  Well it seems that this time the fantasy charts were on to something.  Models show a much colder, more organized system diving into the Great Basin late next weekend/early next week.  It is still very early, but this is the type of winter storm that could bring snow all the way down to the lower valleys with decent, lasting snowfall for the mountains.  The latest versions of the CFSv2 continue to indicate this pattern change in today’s run.  Here is the current forecast for the week of Oct 21-27:

As you can see, it depicts a deep moisture tap taking aim at the entire West Coast of the U.S., the type of pattern that is conducive for good Utah snowfall.  It is still very early to get into any details but it does seem as if there may be a series of systems to affect the area after the initial system.  Something to keep an eye on for sure, as it could be the type of pattern that goes a long way to getting the Utah ski season underway.

However this ends up playing out, we’ll keep you informed.  Hopefully the models continue with this trend instead of backtracking as they did so often last year.  Stay tuned and we’ll keep the updates frequent and detailed . . .


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  • ryan

    Checking in from Santa Barbara, CA…the ocean is still way warmer than usual. It’s still like the summer we don’t usually have. El Nino? Hoping for snow at Pow Mow and SnowBasin this winter.

  • Grandmastapoop

    If the storm that hit us last weekend (Oct. 11-12) were to hit us in the winter, what would we have been looking at for snow? I live in Alpine and it rained non-stop for hours.

    • wasatchsnowcast

      It’s difficult to say—with a colder system (mid-winter), you’d see higher snow:water ratios which would allow snow to pile up much quicker and obviously lower snow levels would allow for snow down closer to the valleys. But that system brought us rain via wrap-around moisture. Most mid-winter systems hammer the mountains a lot harder than the valleys because of orographic lift generated by the terrain’s natural upslope as moisture moves perpendicular to the mountains. But with wrap-around moisture, there isn’t as much lift and therefore as much and sometimes more precipitation falls in the valleys compared to the mountains. If temps were at there average for January, the mountains probably would have gotten 6-12 inches with similar amounts in the valleys. Hope that makes sense!