Wasatch Weather Weenies

Given the fact that we are experiencing our coldest temperatures since February, much of the Salt Lake Valley is snow covered, and we have a 40" base in upper Little Cottonwood Canyon, it may be hard to believe this is going to be the hottest fall on record, but it is going to be the hottest fall on record.  With one day left to go into the record books (today), the average temperature for this fall at the Salt Lake City International Airport sits at 57.7ºF, 0.7ºF warmer than 2015.   Source: NOAA Regional Climate Centers Although we are going to lose a little ground today, my hazy, jet-lagged, early morning math suggests we will come out ahead of 2015 when today is in the books.  Regardless, both years add to our string of five consecutive years with exceptionally warm falls.  How much the recent fall warmth is due to long-term global warming or climate variability is an interesting question.  Thanks to global warming, the dice are loaded for above av...

I've been traveling for work and unfortunately missed out on most of the excitement today.  Further evidence that the best way to ensure a big storm in the Wasatch is to send me out of town. As of 9 PM, it looks like a total at Alta since 0000 MST 27 November (Sunday) of about 40" based on accumulations on the interval board.  Total snow depth broke the 40" barrier this evening, qualifying for the start of "good early season conditions" on the Steenburgh scale. Thanks to Mother Nature for making Utah snow again!

Is there anything better than storm skiing on a day that you can just make out the sun through the clouds?   From last night through 3 PM this afternoon, the Alta-Collins stake has picked up 13" of snow with 0.78" of water.  If you picked your routes carefully to avoid rocks and stumps, the ski touring today was quite nice. Forecasts are optimistic with another trough coming in tomorrow morning with deep moisture and instability. After a lull in the storm tonight, the NAM puts out about 14 inches of snow from 6 am tomorrow morning through 11 AM Tuesday at Alta.  Most of this falls by 11 PM Monday. That's a hefty amount of snow for that model, which doesn't fully capture the influence of the Wasatch Range. Since part of the storm extends beyond the forecast range of the NCAR ensemble, here's the NCEP Short Range Ensemble Forecast (SREF) system plumes for Alta.  Most call for things to pick up tomorrow morning with heavy snow through the day tomor...

The winds were blustery, but the sky sunny for our first day of the season today.   Although there were many tracks, some good powder could be found in shady, wind-sheltered areas.  Even on my old-school touring skis, the kid showed decent form. More snow is in the forecast, which will hopefully help the resorts and the backcountry.

Happy Thanksgiving to all Wasatch Weather Weenies.  We have much to be thankful for. First we have yesterday afternoon's frontal passage, which pushed into the Salt Lake Valley with one hell of a shelf cloud and frontal nose. Second we have the overnight storm, which was fueled by the front, the orographic lift of the central Wasatch, and the lake.  The latter two can be seen below in the form of a narrow, but intense lake band over the southern Great Salt Lake and a region of enhanced radar reflectivity over and upstream of the central Wasatch.  Note also the narrow precipitation shadow downstream of the central Wasatch.  Sorry Wasatch Mountain State Park, no soup for you .   Third we have a spectacular snow coated Thanksgiving Day with clear skies and unlimited visibility.  I love sunrises like this morning's. Finally, we have 12 inches of new snow at Alta, making it two storms in a row that have produced near the top of forecast expec...

There's much to love in the radar loop below taken in the wake of this evening's frontal passage.  The box over the Great Salt Lake shows an area of persistent triggering of lake-effect convection, which trains southeastward into the Salt Lake Valley where it transitions to a broader, more stratiform band.  Meanwhile, the orographic effects in the central Wasatch (larger box) are also persistent and pronounced.  Note the persistent echoes over the high terrain with the abrupt rain shadow further to the southeast.  The Salt Lake County/Utah County line strongly marks the transition. Alta picked up a fast 6" of snow through 8 PM and there's good reason to expect more moderate to heavy snow for the next hour.  After that, everything will depend on the post-frontal and lake-effect crap shoot.

If you are dreaming of a white Thanksgiving you may be in luck. Regional satellite, radar, and 700-mb temperatures over the past 18 hours show the landfall of a Pacific frontal system along the northern California coast followed by its redevelopment over north-central Nevada. That frontal system has its sights set on the Wasatch Front for later today.  The latest HRRR shows the surface cold front pushing through the Salt Lake Valley around 2300 UTC (4 PM MST) this afternoon, with a band of frontal precipitation in its wake for much of the Wasatch Front. Snow levels will drop quickly after frontal passage to bench and eventually valley levels.  This looks to be a quick hitting event, but 1-3 inches on cold surfaces along the east bench of the Salt Lake Valley seems like a good possibility.  Valley accumulations will be less, but perhaps enough to whiten cold surfaces. The HRRR (above) generates lake-effect in the wake of the front, but one needs to be cautiou...

If you are a user of some of our ensemble products on weather.utah.edu, I thought I would share a two pitfalls to avoid. The first pitfall is assuming that ensemble members in the middle of the distribution are more likely to verify than those on the tails.  Although that could be the case, there are times when that's a bad assumption.  Here's an example based on the NCAR ensemble forecast for Alta Collins for the 2-day period ending this afternoon and encompassing our most recent storm (focus on the top graph).  In the NCAR ensemble, every member is an equally likely outcome.  And, in this particular forecast, the outcomes are relatively evenly distributed.  The odds of 0.6 inches are about the same as 1.4 inches (the latter verified).   Hedging your forecast to a subset of the plumes makes little sense when the distribution of forecasts is so even.  It might make sense when there is a strong clustering of forecasts, but one also needs to...

Over the past few days I've been looking at the medium range ensembles and, although I don't see a storm in the next week to get excited about, there is a series of modest events that should slowly but surely add to our non-existent to meager snowpack.  We start with last night's precipitation (upper-elevation snow only), see a bit more today and tonight (with lower snow levels), and continue with a couple more storms over the next week. Source: weather.utah.edu Water and snowfall totals presently being advertised by the models for the next week are not game changers, except perhaps for the wettest, snowiest ensemble members.  Looking beyond the 1-week period presented above, there's hope of continued activity, but I don't like to talk about details in such long-range forecasts.   Thus, it looks like this ski season will come in with a whimper, not a bang.  We'll get a little here and there.  Resorts may open a trail or two with snowmaking during the T...

Everyone along the Wasatch Front and Back awakes this morning to a beautiful day with a think veil of high clouds blanketed over snowy mountains. Everyone that is except for the snowmakers. Toying with the idea of skinning and skiing the white ribbon of death down Collins Gulch tomorrow, I took a look at the web cams from Alta and saw nothing in the way of operating snow guns. How can this be?  A building ridge and southwesterly flow conspired to raise our temperatures dramatically last night.  Check out the temperatures at Alta Base over the past 24 hours.  We peaked at 33ºF yesterday and cooled into the mid 20s shortly after sunset.  Then, after midnight, temperatures rose dramatically and currently hover near 40ºF. There are, however, a few places where shallow pools of cold air did not scour out of valleys or basins.  For example, temperatures in the Snyderville Basin and near the base of Park City Mountain Resort remain below freezing th...

Our first all elevation "winter storm" of the season is winding down.  Radar imagery from 1221–1512 UTC (0521–0812 MST) shows the last gasp of lake- and mountain enhanced showers decaying and moving downstream. We had just enough to coat the grass around campus.  Up at Alta-Collins, there is a 5" snow total with 0.27" of water equivalent, clearly on the low end of the most likely range we discussed yesterday.  Maybe they will pick up a bit more, but these are pretty paltry numbers and nothing to get excited about. I don't know what you people have done to irritate Mother Nature, but kiss and make up now.  This has been going on for 5 years now.   FIVE LONG YEARS .  I'm not getting any younger and I don't want this year to be a sixth.

In this post, I will be channeling Donald Rumsfeld, who once famously said. " There are known knowns. There are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know. " Rumsfeld was lampooned for that quote, which many considered to be nonsense, but I understand exactly what he meant. Known Knowns Our computer models have gotten pretty good at predicting large-scale airmass changes.  That's why the massive drop in temperature from yesterday (record high of 73ºF and the latest 73ºF on record at the Salt Lake City airport) to tomorrow morning (low 30s) is a known known.  Think of this period as a time machine in which you are transported from early Fall to late Fall in two days.  We are in transit today as cooler air is already moving in aloft and the surface front, marking the leading edge of even cooler air, is...

I guess we can call today the unofficial last day of summer.  I was going to put summer in quotes, but it is not as ridiculous as it sounds. This morning's sounding had a 700-mb temperature of 6.8ºC, which represents the average for mid September, technically not meteorological summer, but within astronomical summer. Source: SPC It should be noted, however, that there have been higher 700-mb temperatures observed at the airport in November, including 8.7ºC on Nov 19 (LST).  Model forecasts for later this afternoon top out at 7.6ºC (NAM) and 6.9ºC, so we're not in completely rarified air yet. Nevertheless, the day is going to be splendid, with the maximum temperature constrained only by how much we mix out the strong valley inversion that was present this morning (see above).  At 11 am, we were at 63ºF at the airport and 65ºF at the University of Utah.  Bench locations will likely eclipse 70ºF today.  The maximum at the airport is, however, quite trick...

It has been a remarkable fall across the entire Northern Hemisphere.  The large-scale upper-level pattern has been totally locked in.  As shown by the mean (left hand side) and departure from average (a.k.a. anomaly, right hand side) 500-mb analyses below, the pattern has featured anomalous troughing over the northeast Pacific, ridging over North America, and ridging over the North Atlantic and Arctic. Source: NOAA/ESRL That large-scale pattern remains in force today, leading to well above average temperatures in the Arctic, where sea-ice coverage is at a record low and above average temperatures across much of North America.  In contrast, ,below average temperatures exist across much of Eurasia, especially Siberia.  Source: ClimateReanalyzer.org This weekend, I watched some of the World Cup skiing races from Levi, Finland and it was like viewing another planet as it sure looked like winter there, whereas here in Utah I threw on shorts and a t-shirt...

During the past week, Rocky Mountain Power announced that they are recommending a three-part monthly rate increase for future residential net-metered solar customers, including a $15 fixed charge, a $9.02 per kilowatt for peak period demand, and 3.81 cents per killowatt-hour for the amount of energy used.  While not applying to existing home solar produces, this would greatly disincentivize future installations. The argument for doing this is based on a study conducted by Rocky Mountain Power claiming that rooftop solar customers are underpaying their actual cost of service by $400 per year.  Subsequently, Rocky Mountain Power's external communications director Paul Murphy argued in an op-ed piece in today's Salt Lake Tribune that Rocky Mountain Power is committed to solar and customer fairness, but that the cost noted above represents a substantial subsidy. If Rocky Mountain Power is committed to solar (and I doubt that they are), this action clearly shows that they ...

When in a snow drought at the beginning of the season, one tends to look into the deep future for any trough that might lay down some snow.  Indeed, we have one in the forecast, which the GFS pushes through the state next Thursday. This storm is already being hyped, despite the fact that its nearly a week away.  There are some things we can be confident in.  For example, we are going to get colder later next week.  However, you really can't count on precipitation amount forecasts that far in advance.  The storm track could change some and, when it comes to Wasatch snowfall, the Devil is in the details, and those details can't be reliably anticipated at such long lead times. To further sober you up, rather than show one exciting solution from the GFS, let's look at the NAEFS downscaled ensemble forecast for Alta.  There are a few members calling for 10-20 inches on Thursday, but others going for quite a bit less. Bottom Line: There remain a wide ...

Salt Lake Valley from the Bonneville Shoreline Trail, 4 PM 9 November A seriously nasty post-election smog episode has settled in over the Salt Lake Valley today.  Visually, it basically looks like crap.  Here are a couple of more photos of Downtown and the Wasatch Range from the Bonneville Shoreline Trail.  The setup for this event is important for two reasons.  First, we did not have a previous surge of low-level cold air prior to the development of the high-amplitude ridge over the past few days.  Second, there is no snow cover.  As a result, the cold pool that is present over the Great Salt Lake Basin is relatively weak.  In fact, yesterday's high at the Salt Lake City airport was a remarkable 69ºF and some sites in the valley peaked above 70ºF. OK, so perhaps the air quality won't be that bad, right?  Wrong!  There are two flies in the ointment making our lives miserable.  The first is that we continue to burn fossil f...

In the wake of the national election, I've seen several articles, blogs and quotes suggesting that the election of Donald Trump is a disaster for efforts to reduce carbon emissions and address global warming. It is certainly not good news in those areas, but the situation is not necessarily hopeless. Carbon emissions in the United States come from several sectors including electricity generation, transportation, industry, agriculture, and commercial/residential.  The electric power sector represents one of the brighter areas in which the US has "bent" the carbon emissions curve, with a general decline over the past several years. Source: US Energy Information Administration The causes for the decline are multifaceted, but include increased use of renewables (especially solar and wind) and a transition from coal to natural gas, which is less carbon intensive (but still carbon emitting).   Source: US Energy Information Administration As a candidate, Mr. Trump...