Wasatch Weather Weenies

The media is abuzz with reports that Trump is going to withdraw from the Paris Agreement.  This isn't really a surprise since he's consistently said he would do so and every action he's taken as President is consistent with doubling down on fossil fuels. In contrast, the Paris Agreement seeks to "[hold] the increase in the global average temperature to well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change." Let's ponder those numbers, although there are a few challenges to doing so.  Incredibly, preindustrial isn't defined in the Paris Agreement (a major oversight), so we need to think about it for a bit.  Scientifically, we wouldn't want to pick a single year because in any one year, natural climate variability, volcanic eruptions, and other factors might make that year an...

Last weekend was simply splendid across northern Utah with mostly sunny skies, high temperatures in the 70s and 80s in the Salt Lake Valley, and a nice breeze. However, we will take a run at 90 today at the Salt Lake City International Airport, with temperatures climbing a bit further and peaking even higher tomorrow.  The NAM forecast valid 6 PM MDT tomorrow shows a warm, southerly flow in advance of an approaching trough with 700-mb temperatures right around 12ºC. I've long considered a 700-mb temperature of 12ºC to be the lower threshold of summer misery.  Below that and afternoon temperatures in the Salt Lake Valley are tolerable.  Above it lies misery, that increases exponentially as temperatures increase further. Climatology shows this fairly well.  700-mb temperatures average around or above 12ºC at the Salt Lake City airport from early July through mid August.  You know.  The dog days of summer. Source: SPC The good news is that temper...

In many ways, Memorial Day Weekend is one of the prettiest times of year in the Salt Lake Valley.  The mountains are still snow covered and the valley and foothills are green.  I never feel bad staying home for the holiday weekend and avoiding the traffic and the crowds elsewhere. I got up early yesterday and climbed Mt. Wire.  It's a good early season hike for getting the legs in shape for bigger adventures and it offers a wonderful view for a meteorologist who likes to think about what happens when westerly or northwesterly flow strikes the Wasatch Front. Mountain biking on the Ensign ridge this morning offered up a perspective on Farmington Bay, which finally has some water in it again! If you've been up in the foothills, you've probably noticed that a lot of the scrub oak leaves are damaged.  I think this happened during the snowstorm a couple of weeks ago.  Such a shame.  I wonder if they will push out another set of leaves in the next coup...

I was going to issue a Memorial Day Forecast this morning, but then I noticed none of the products on weather.utah.edu have updated since yesterday.  Good think this isn't ski season! Thus, I'll just pass along the NWS graphic, which oddly is missing the NOAA/NWS logo. Source: NWS Other than some showers and thunderstorms today, and perhaps an isolated shower or thunderstorm in eastern Utah tomorrow, the weekend is looking quite pleasant.  Enjoy!

Source: https://www.pinterest.com/pattybartz/richard-feynman/ Paraphrasing Mark Twain, money is for spending and budgets are for fighting over. Most Americans would probably agree that federal spending needs to be reduced.  However, the President's Budget released yesterday takes a draconian axe to many science and education programs that are critical investments for the Nation.  The Scientific American summarizes the some of the cuts affecting science and education  here .  I will discuss specifically cuts proposed to science agencies and programs that I believe will greatly slow progress in weather and climate prediction. My science career now spans nearly 30 years and for that entire time I have received support from the National Science Foundation (NSF).  I consider NSF to be the gold standard of science funding agencies.  They support research projects initiated by scientists and are probably the most "organic" funding agency for...

With Memorial Day weekend approaching, I've been thinking of heading to higher country for some turns. The Uinta snowpack remains quite fat.  The numbers from the Trial Lake Snotel, very near the Mirror Lake Highway, show an early May peak in snowpack snow water equivalent just under 50 inches, roughly double the median peak.  Despite some losses in the middle of the month, they currently sit over 30 inches, again roughly double median. Source: CBRFC The question is, will the Mirror Lake Highway be open?  According to a n article published in the Deseret News over the weekend , UDOT is giving it a 50/50 chance. If the road does open, you're going to find an impressive snowpack by Uinta standards.  If not too snirty, there's going to be a good corn harvest up there over the next couple of weeks.

Living at the base of the Wasatch Range, I don't travel very much for skiing.  Skiing is costly, and my academic calendar means the only time I can get a full week off is either prior to Christmas when the snowpack is meager, during the holidays when everything is expensive or crowded, or during spring break, which can sometimes be quite warm. This past season, however, I got the big crow bar out and cracked open the wallet to purchase Mountain Collective passes for my son and I.  Given my advanced age, I also bought the optional insurance, raising the price to $449 each.  After a season of skiing (with some potential we will still travel to a couple more resorts), here are my perspectives. Pluses I have no prior experience with multi-resort passes.  I suppose I could have sprung for an Epic Pass or a M.A.X. Pass, but the mountain collective includes many iconic resorts, several of which have great snow and terrain. For someone based in Salt Lake, there...

I've had an unused day of skiing at AltaBird thanks to my Mountain Collective Pass and decided I'd use it today.  With a fresh coat of the white stuff, the mountains were quite stunning this morning. Conditions were quite good for May 20th.  Carveable up high, some refrozen spring snow down low.  Stuff softening up depending on aspect as the day went along. Given that I hadn't ridden lifts in a month, we racked up vertical on the groomers and called it good at noon.  I like the 8 am open.  That's really nice this time of year for early risers like myself. Unfortunately, the snow under the fresh coat looks pretty dirty.  In a couple of days, we'll be skiing snirt instead of snow.

Official temperature records are kept for the surface, but let's give some love today to the atmosphere aloft. The cold upper-level trough that moving through our area is a record setter.  Soundings collected 0000 UTC (1800 MDT) yesterday afternoon and 1200 UTC (0600 MDT) this morning broke records for the coldest temperature observed at that date and time at 700 mb (about 10,000 ft/3,000 m) and 500 mb (about 18,000 ft/5,500 m). 700 mb 00z 18 May 2017: -9.1˚C Prior Record: -9.0˚C 12z 18 May 2017: -9.5˚C Prior Record: -9.2˚C 500 mb 00z 18 May: -28.7˚C Prior Record: -27.8˚C 12z 18 May: -27.7ºC Prior Record: -25.1˚C Prior records are based on soundings collected at Ogden and Salt Lake City from 1948-2014, although there are gaps in which no data is available.  Thus, these upper-air records are perhaps not as impressive as a record at the surface where there is a much longer history available.  Still, it provides some illustration that this is a...

With about 6 inches of new overnight on top of a frozen coral reef base, expectations were fairly low for high quality powder skiing, but the skiing was fun this morning up at Alta.  Below, my son Erik does his best to make it look deeper than it really was ;-). High density snow with some wind actually buried the really nasty stuff in low-angle terrain areas. The bottom made itself more noticeable in steeper terrain.  A few people were skiing the Main Chute, which perhaps was blown in better. With a pretty good breeze and my summer acclimatization, I was cold the entire morning, even on the descent with the puffy jacket on.  A few weeks of warm weather, including some time in Florida where temperatures reached the 90s, has made me soft.

OK, the cat is out of the bag.  An unusually cold airmass is on its way to Utah.  The question is, will we get some decent mid-May deep powder skiing? Let's start with the temperatures.  The loop below shows GFS 700-mb (about 10,000 ft above sea leavel) temperature analyses and forecasts from 1200 UTC 14 May (0600 MDT Sunday) through 1200 UTC 18 May (0600 MDT Thursday).  Note how the tightly wrapped core of cold air over the Gulf of Alaska slides down along the Pacific coast and then moves inland to directly over northern Utah. Air that cold is pretty unusual in our part of the world in mid to late May.  In fact, 700-mb temperatures below -10ºC have never been observed at the Salt Lake City airport after May 12th, although we've been close. Source: SPC We'd have a shot at getting a -10ºC in the record books except soundings are only taken twice a day, at 1200 UTC (0600 MDT) and 0000 UTC (1800 MDT) and it appears right now that the coldest air at 700...

May 16, 2015.  A reminder that late-spring storms are part of the Wasatch climatology. We've said it many times this spring, it ain't over until its over .  It was only a few days ago that I was bemoaning the return of colder weather to California as I was thinking of a Sierra corn harvest trip.  Well, if I'm lucky, things might just work out just fine, but in an unanticipated way.  Forecasts from the day of that post showed a deep, closed, upper-level flow digging through northern California on its way to the southern Sierra.  Not a great scenario for either Sierra corn or, for that matter, Wasatch powder. However, forecasts change and that trough is now expected to amplify later and moves into the western U.S. as an open wave accompanied by a strong cold front that is expected to push through northern Utah late Tuesday night and early Wednesday morning. Ooooh, the lower right hand panel of that GFS forecast is a beauty! The forecast, however, i...

Projections of how climate change will impact snow and skiing are of great interest to readers of this blog.  There are, however, a number of major challenges to making these projections.  Our climate models have large grid spacings, which means they do not explicitly simulate the effects of nearly all mountain barriers on precipitation, humidity, temperature, etc.  Without reasonable mountains, they don't explicitly simulate the mountain snowpack, or the effects of elevation and aspect on that snowpack.  Therefore, projecting how snow will change in the future typically requires some modeling gymnastics to account for local effects in mountainous regions. A recent paper by Wobus et al. in Global Environmental Change  uses a variety of approaches to project future climate change impacts on snow, skiing, and snowmobiling in the contiguous United States.  The paper is unique in that it doesn't focus on a particular ski area or region, but instead provides a...

With the semester over, I've been doing some California dreaming and debating whether or not to drive over to the Sierra for a few days of blue skies, California sun, and corn harvesting. The snowpack there is, of course, outrageous.  Having achieved remarkable depths by April, the Sierra snowpack now shows clear signs of ripening and melt in mid elevations of the southern and northern Sierra.  I suspect things have corned up nicely, with only timing the key for good turns.   However, there is a fly in the ointment for the future.  Medium-range forecasts show a transition beginning on Friday and upper-level troughing persisting along the Pacific coast for about 5-7 days thereafter.   Perhaps this weekend things will still corn up during the afternoon, but next week the pattern is one that will eventually produce highly variable conditions with everything from coral reef to cream on crust.  Later in the period, perhaps they will eve...

Yesterday afternoon, a series of convective storms formed over or near the central Wasatch and moved northwestward toward Bountiful and portions of the Salt Lake Valley. The first of these storms was near Parley's Canyon at 2059 UTC (1459 MDT) and organized in a line. It looked like a close call for the University of Utah to receive rain, as well as thunder and lightning. Over the next 13 minutes, the storm shifted northward and became more cellular in structure.  By that time, it was northeast of campus and we had missed out on any significant precipitation. However, it is important to realize that threats from lightning can often extend many miles from the rain shaft and indeed, that was the case yesterday.  I was taking the occasional glance at the wonderful lightning products at lightningmaps.org and noticed a strike not only on Little Black Mountain close to the storm, but also in the mouth of City Creek Canyon, not far from downtown. That strike illust...

It's no news to readers of this blog that California has had a winter for the ages.  As of May 5th, automated snowpack sensors showed the snowpack in the northern Sierra/Trinity region at 189% of average, central Sierra at 193% of average, and southern Sierra at 168% of average. Those numbers are impressive, but here are the peak snow depths from manual snow course measurements taken in late April and early May from each region: Northern Sierra/Trinity: Lower Lasen Peak, 8250 ft, 266" snow depth, 131.5" water content Central Sierra: Bond Pass, 9300 ft, 192" snow depth, 101.0" water content Southern Sierra: Piute Pass, 11,300 ft, 166.5" snow depth, 85.0 inch water content For comparison, the Alta-Collins snow depth sensor and Snowbird SNOTEL measured 125" snow depth and 58.3" of water equivalent yesterday. Stay thirsty my friends...

This morning's sounding showed classic conditions for strong microburst winds with an "inverted V" profile created by the temperature (red) and dewpoint (green) traces above the shallow surface-based nocturnal inversion. Source: SPC Microbursts are are sudden strong winds caused by downdrafts induced by precipitation and may be "wet" or "dry", with the latter occurring when the precipitation evaporates before reaching the ground. Source: Wikipedia One measure of the potential for strong downdrafts and microburst winds is what is known as the downward convective available potential energy or DCAPE.  DCAPE is maximum energy available for a negatively buoyant parcel of air cooled by evaporation assuming no mixing with the environment.  Values above 1000 Joules/kg are considered high and significant.  This morning, the DCAPE at Salt Lake City international airport was 1223 Joules/kg. Not surprisingly, we've had some strong winds in norther...

As we discussed a few weeks ago, the ski season is never over until it's over .  That being said, we are probably very close to the "beginning of the end." By beginning of the end, I mean the onset of the rapid decline in snowpack on upper-elevation northerly aspects. The low-elevation snowpack already suffered a premature death in March with the beginning of the end produced by the unseasonably furnace-like temperatures we experienced in the middle of the month. The snowpack at mid-elevation and relatively sun exposed upper-elevation areas has, however, been able to stave off the beginning of the end for a remarkably long period of time.  For example, peak SWE at the Mill-D North SNOTEL was reached in early March.  Since then, there have been two melt periods, each followed by an accumulation period.  The most recent peak in SWE, achieved on May 1, was just a bit below the early March peak. At Snowbird, which benefits from both elevation and north aspect,...

The University-wide commencement ceremonies for the University of Utah are tomorrow (Thursday) night, with most college ceremonies on Friday.  Although the ceremonies are indoors, we do our best here at the University of Utah Weather Control Center to arrange for nice weather for your photographs and outdoor activities.  We have conjured up an ideal pattern for tomorrow night, with an upper-level ridge in full control. Friday looks nice as well, with a south breeze in the afternoon.  Other than perhaps having to hold your mortarboard as you walk around campus later in the day, things look just fine. Tomorrow night's commencement address will be given by Conrad Anker.   Conrad is a U alum and mountaineer, most recently featured in the film  Meru , which won the US Audience Documentary Award at the 2015 Sundance Film Festival. Decision making by the U administration has come into question recently, but they made a good choice in selecting Conrad. ...