Thursday, March 26, 2020

The "Perfect Storm"

I love spring storms that bring snow to the mountains, accumulating snow to my yard, but little to no accumulation on the sidewalks and roads.  Last night's nailed it in the upper Avenues, pictured below. 
Valley areas where snowfall rates were higher probably are seeing some accumulations on roads, but like politics, all weather is local, and for me, this storm is perfect.

Through 7 am, Alta-Collins shows 8 inches on the stake since late yesterday.  The Utah Avalanche Center reports a total snowfall for the week of 12-21 inches in the central Wasatch and just over 2 feet in the northern Wasatch.  I suspect the riding conditions today will be outstanding and some of the best of the season.  Enjoy but be careful and keep your distance out there.

Wednesday, March 25, 2020

Complexities of Great Basin Weather in Spring

It was a wet night and morning in Salt Lake City, with a bit of the white stuff dusting the ground earlier this morning in the upper Avenues.

Snowfall during the 24-hour period ending at noon today appears to be about 11 inches at Alta Collins.  Thusfar, it's a pretty good event, with more on the way.

It's really interesting to look at what has been happening and what will happen from yesterday through tomorrow morning.  During this period, a large-scale upper-level trough is digging southward off the Pacific coast, resuting in southwesterly large-scale flow across the Great Basin.

At 2100 UTC (1500 MDT) yesterday, the 700-mb analysis showed evidence of flow splitting around the southern high Sierra, with confluent flow over central Nevada where there was a weak wind shift from SW flow to the south to west-southwest flow to the north.

Precipitation was not organized along that wind shift, but instead was widely scattered as convection developed due to heating of the weak stability airmass.

In the absence of surface heating overnight, however, the precipitation became more continuous along the wind shift, and this morning the resulting precipitation band was centered over the Salt Lake Valley and central Wasatch.

This band weakened as one moved southwestward toward Nevada.  There were some showers near Elko, but otherwise, the action was along the wind shift where there was also a weak temperature gradient.  One might call this a front, but a meteorologist might instead call it a baroclinic trough.

However, with surface heating today, we are seeing a breakup of the precipitation band and a transition to scattered convective showers.  This is a nice example of the diurnal modulation of precipitation processes in the presence of weak stability and daytime surface heating.

Throughout this period, the confluent wind pattern remained over the Great Basin.  In fact, it has moved perhaps 100 km southward.

Overnight, forecasts show that it remains stationary through 0000 UTC (1800 MDT) this afternoon, although it begins to move southward near the Sierra Nevada by 0600 UTC (0000 MDT) tonight.

Note how the NAM forecast above calls for the precipitation to redevelop along/near the wind shift overnight in the absence of surface heating, as happened last night.

Even by 1800 UTC tomorrow, the 700 mb wind shift remains pretty much over the Salt Lake Valley.

Thus, this slow moving feature will continue to dominate our weather through tomorrow, with transitions in the characteristics of the precipitation.  With temperatures slowly decreasing during the period, I suspect ski conditions tomorrow will be quite good, if it doesn't get too deep as it appears that another 8 to 16 inches are likely in upper Little Cottonwood through tomorrow afternoon.  Respect uphill closures at the result, make adjustments for avy conditions, and, as noted in the video below, "this is not the time to get sendy."

Tuesday, March 24, 2020

Recommended Reading

Apologies to my readers out there.  There's quite a bit of weather happening and on tap for this week, but I've found blogging to be difficult.  I hope this will change in the near future.  Perhaps if the weather gets a little more exciting than yesterday's scattered thunderstorms. 

One of the things I am doing to deal with these uncertain times is to read.  And when I say read, I don't mean news or social media, but books.  Last night I was looking for a challenge and I decided to crack open a book that I received as a gift, was published in 1997, and has been sitting on my end table for many months: The Adirondacks: A History of America's First Wilderness

I was fortunate to grow up adventuring in the Adirondacks and any time I read about them, happy memories surface.  I'm not far enough into the book to recommend it yet, but it has already reminded me of the smell of rotting leaves in the late fall, the way that a canoe paddle breaks the surface of the water on a calm day, and the tip toeing to keep boots dry during a hike through a bog.  I need mental escapes like these in trying times. 

Amongst books I have read recently, you might try Rocket Men by Robert Kurson.

I may have recommended this book previously, but it's a good on on the lesser-known story of Apollo 8, which was the first journey of humans to the moon.  Gripping and exciting and it will help remind you that we can be bold and accomplish great things. 

For something completely different, you might try  Daisy Jones & the Six.

 It is a fake-history book about a band that never existed and full of Rock and Roll cliché, but it is fast paced and mindless reading.  It might be just what the doctor ordered, although if you hate it, you didn't hear about it from me.

Reading a book about nuclear disaster might not be the best option right now, but Midnight in Chernobyl is one of the best historical accounts that I have read in a long time. 

There are a number of books on the Chernobyl disaster and I've heard that some are not very good, but I found this one to be terrifying and gripping. 

Finally, if you want something a little lighter, but still with insights into serious issues, you could try Born a Crime by the Daily Show's Trevor Noah. 

I expected this to be an entertaining and humous book, and it was.  What I didn't expect were the insights into the evils of Apartheid.  It's easy reading that will distract you from the challenges of the day. 

Saturday, March 21, 2020

Back from the Road

It's been a long couple of days as I drove down to Tempe to extract my daughter from Arizona State.  Snow in Flagstaff required me to go through Vegas on the way down, which turned out to be fairly nice as the low desert is pretty green right now.  Returning we were able to drive through Flagstaff and it's really cool to start in saguaro forest and get to snow on the Mogollon Rim.  Sorry I didn't take any photos, but we didn't stop except when absolutely necessary, typically at the loneliest, most expensive gas stations we could find. 

I've been looking at the forecasts and they are difficult to summarize succinctly.  Overall, I would describe the pattern for the next several days as typical of spring, which means changeable and showery, with the potential for cooler weather later in the week.  A warmer trough (valley rain, mountain snow) will pass Sunday night and Monday, followed by a deeper trough with cooler air that will dig over the western U.S. and move through slowly later in the week.

Mountain snow is likely at times next week, but timing and intensity is difficult to nail down at this time.  The most probable time for mountain snow will probably be somewhere in the Tuesday-Wednesday time frame when many of the ensemble members bring the cold front in advance of the deeper trough though northern Utah.  This is when snowfall increases the most in the NAEFS plumes. 

This suggests Wednesday or Thursday might be this week's sweet spot for skiing, although much will depend on how things play out.  Regardless, I'm starting to see recommendations from search and rescue groups in other states (e.g., Colorado) asking people to dial back the risks.  Here's an example from Colorado public radio.  The challenges facing our first responders and medical communities are growing rapidly now.  Consider this in making your recreation choices.

Wednesday, March 18, 2020

University Instruction during the COVID-19 Crisis

Adding insult to injury, Salt Laker's were shaken this morning by what is estimated as a 5.7 magnitude earthquake centered near Magna in the northwest Salt Lake Valley.  All is well with me and my family and I hope the same for you and yours.  For information on what to do before, during, and after an earthquake, see  Below is their drop, cover, and hold on reminder.  Note that if you can't get under sturdy furniture like a table or desk, crawl to an interior wall and away from the windows. 

Source: FEMA

I did not receive word from the University of Utah that classes were cancelled today until I was halfway through my morning class, which I was teaching online for the first time.  Although I have never taught it online before, the course is laid out in a way that is quite amenable to transitioning to online instruction.  It is a "flipped" class in which the students complete online instructional modules on their own.  When we meet, I lead them through a forecasting exercise. 

I have taught this class in this way for 25 years, so when I first attended a seminar on the flipped classroom I laughed and realized I've been teaching that way for a long time, although not all of my courses are designed in this way. 

Today's class seemed to go well since the students can forecast on their personal computers (although not necessarily using the software we have in our lab) and we can communicate and share screens and ideas using video conferencing software.  It's not quite as good as being there, but I think the class experience should be a good one considering the circumstances.

That being said, I am already pushing back due dates on assignments and considering some changes to the course.  Our lives are disrupted and stress is high.  Expectations for students and ourselves need to be adjusted.  Spending less time covering material and more time just talking with students about how they feel is critical.  None of us has been through anything like this before, but most undergraduates cannot remember 9/11 and have limited recollection of the 2008 financial crisis.  It is worth remembering that this is probably the first major societal upheaval that they have experienced and even for those of us mid-career types, it could be the worst of our lifetimes.    If you are a faculty member, stay in contact with your students. If you are a student, respond when we check in or just contact us for any reason.  We're here for you. 

Sunday, March 15, 2020

A Persistent Blow

Sick of the wind?  Many are as it's been persistent and gusty now for a period spanning about 36 hours in the Salt Lake Valley.

Observations from the University of Utah show southerly winds picking up in earnest around 0000 MDT 14 March (Saturday).  There was a brief letdown early Saturday morning, and then a peak late that afternoon.  Winds blew fairly steadily overnight as well, with a brief letdown just after 6 am this morning.

Source: MesoWest
 This is one observation location, so what happened at your home may have differed somewhat, but for the most part, it's been a persistently windy time.

Over the past 24 hours, the strongest winds have been in the Wasatch Mountains, including a peak gust of 99 mph at the top of Snowbasin's Strawberry Bowl early this morning.  At lower elevations, there was a gust of 64 mph in Parley's Canyon near the quarry, 57 mph in the upper Avenues, 54 mph in Provo and Herriman. 

The strong southerlies will continue today, with a chance of scattered showers and thunderstorms this afternoon. 

Friday, March 13, 2020

COVID-19 Impacts on Skiing

Following Italy, all ski areas in the Austrian states of Tyrol, Saltzburg, and Vorarlberg will be closing after Sunday due to COVID-19.  Most of Austria's major ski resorts are in these states.

Early afternoon après in St. Anton.
It's fortunate for the local economies that it is near the end of the high season, although the loss of a few weeks of revenue will still not be easy.  Austria has 254 ski areas with 5 lifts or more and nearly 35 million skier visits by foreign skiers.  Winter tourism in Austria generates 11.4 billion euros in direct and indirect revenues, representing 5% of Austria's GDP.  I suspect, however, that most Austrians support this move as they recognize the threat at hand.

Here in Utah, the resorts continue to operate.  However, Snowbird closed its tram today.  Below is a screenshot from today's mountain report.

In the overall scheme of things, it's just skiing.  I never thought I would say that, but perspectives change.

Addendum @ 8:45 AM MDT Saturday 14 March 2020

Now seeing reports that some resorts in Switzerland are closed or will be closing after the weekend.  I saw a media report that Zermatt, which is open all year, will close until April 30, but have not been able to confirm this.

In Vermont, media reports suggest that Jay Peak and Burke Mountain will close after today (Saturday).  Utah resorts tweeted yesterday that they are still open, but Snowbird has closed the tram (as has Jackson Hole).

Addendum @ 9:00 AM MDT Saturday 14 March 2020

A couple screenshots from illustrating what is happening in St. Anton, one of Austria's major ski areas.  Click to enlarge.

Thursday, March 12, 2020

Spring Break and a Bit Thereafter

What do University faculty do during spring break?  For me it depends on the weather.   This year I've had to do a number of software upgrades for my forecasting class, prep for moving online, and put out a few fires related to COVID-19, so I've been working.  I've also been alternating between biking and skate skiing for my daily workouts.  It's a nice mix and good social distancing. 

Today we face an uncertain future, and I'm not talking about COVID-19.  Instead, I'm talking about the medium range snow forecast.

There are two challenges.  First, there is a major transition in the large-scale flow pattern over the north Pacific basin forecast to occur over the next several days.  As depicted by the GFS forecast below, we have a major omega-block developing, characterized by high-amplitude ridging over the Gulf of Alaska, flanked by troughs to the west and east, the latter near the US west coast. 

We can have confidence in the omega block developing, but in such a pattern, the local conditions in the Wasatch Range are very dependent on the details of the closed low and its position and movement across the west.  So that's one source of uncertainty.

The second is that the precipitation associated with the closed low will come in fits and starts, which are very difficult to time and anticipate intensity for at long lead time. 

Thus, if we look at the NAEFS plume for Alta Collins, we see quite a bit of spread.  Through  0000 UTC 17 March (6 PM MDT Monday), there are ensemble members generating just a couple of inches of snow for Alta, whereas there are a few others that generate 10-20 inches.  Even through 0000 UTC 19 March (6 PM MDT Wednesday), the range of all but two outlier Canadian members is 2 to 38 inches. 

One thing that is likely is whatever we get, the storm will be warm and the snow will likely be high density.  That might be a good thing if we don't see a lot of snow as it will help smooth things out.

Bottom line: Keep expectations low, hope for the best, and wash your hands. 

Wednesday, March 11, 2020

Universities Go Online in Response to COVID-19

We don’t know when a pandemic might strike, but we can be sure of two things.
Everything we do before a pandemic will seem alarmist.
Everything we do after a pandemic will seem inadequate.
This is the dilemma we face, but it should not stop us from doing what we can to prepare.
– Mike Leavitt, Former Gov. of Utah and
Secretary of Health and Human Services, June 13, 2007
According to the Johns Hopkins COVID-19 tracker, there have now been 121,061 confirmed cases of COVID-19 world wide with 4,368 deaths.  In the US, there have been 1,039 with 29 deaths.

Several US universities, including the Universities of Washington, Stanford, and Harvard, have or will be moving classes online.  Others may follow.  As things stand this morning, the University of Utah has not yet done this, but is reviewing the feasibility of doing so and is encouraging faculty to consider new methods of teaching to limit potential exposure in the classroom.  Below is the official statement issued by President Ruth Watkins on Monday, 9 March.
We are not cancelling on-campus classes at this time, but we are reviewing the feasibility of moving large enrollment classes to online formats in place of in-person instruction. University Teaching & Learning Technologies has developed a Canvas “Fast Course” for activating online class environments and embedding lectures and class announcements that will be updated by the end of business today (03/09). Please encourage your faculty to consider new methods of teaching this semester to limit potential exposure in our classrooms.
If we were to move online, which I would support given the seriousness of rapid COVID-19 spread, a possible positive outcome would be greater exposure of our faculty to online pedagogical techniques and teaching tools.  However, we should not fool ourselves that (a) the faculty are prepared to teach online with so little prep time, (b) the quality of instruction will not suffer, and (c) all courses can be taught online.

Fully online course delivery can work very well for some types of instruction with proper planning and course design.  More commonly, a mixture of in-class and online techniques enhances instruction, with the weighting of that mixture dependent on the topic and content.

Some of our faculty are trained and well prepared for online course delivery.  Others not.  For some, a rapid shift to online is a bit like taking a Tour de France cyclist and asking them to become a Nordic ski racer in a week.  They might have the cardiovascular engine, but they need to learn the technique and they have to train a new set of muscles.  I am in the early stages of designing an online course.  It's not the same as developing an in class course and it takes time to learn the tricks of the trade.

There are other classes that just cannot be taught well online.  I am thinking specifically of hands-on lab classes.  Even the weather forecasting class that I am teaching will suffer some.  I have no doubt that I can teach it online, but in most instances the students will not have access to the same software, computer power, and internet bandwidth that we have in our computer lab, although I can make efforts to see if they can replicate some of it on their laptops or home computers.

Finally, while we think of students as tech savvy and having access to whatever device they need at all times, this is simply not the case for many.   Some may not have access to reliable internet (at my house, the internet is up and down all the time!).  Some may not have access to the computer resources for completing class tasks efficiently (it is definitely an advantage for weather forecasting to have a big monitor or multiple monitors).

These are not arguments against moving to online delivery.  As we have seen in Italy, it may take drastic measures to limit the spread of COVID-19 and reduce strain on the health system.  If it must be done, it must be done.  I see some potentially positive outcomes if we move online in terms of broader faculty engagement with online teaching tools and techniques.  However, we should recognize that this is going to be a major challenge.

Monday, March 9, 2020

This Is Starting to Get Old

I don't know about you, but I'm starting to feel powder deprived.  Alta's new website has some nice visualizations for snowfall at the resort.  Looking at the graph below, which shows the daily new snow, one can see we haven't had a 10+ inch dump since February 16 and that the small storms that we have had have also been spread out.  December and January clearly spoiled me and probably you. 

Monday's have been pretty repeatable the past couple of weeks.  I come in, look at a dismal pattern, pull up the NAEFS plumes, and see a flatline for the work week with a possibility of some snow the next weekend.  Today is no different. 

Given that this week is spring break, this isn't the storm-skiing pattern I was hoping for.  A few dribs and drabs possible, but otherwise nothing too exciting.  On the other hand, I'm in decent Nordic shape this year, so perhaps I'll just stick to that and biking. 

Saturday, March 7, 2020

March Becoming a Lamb

If it seems like March is milder than it used to be in Salt Lake City, you're right.

Looking at decadal-average temperatures at the Salt Lake City International Airport shows that March was warmer over the past 10 years than any other prior decade ending in 9.  The mean march temperature for 2010–2019 was 46.5˚F, 1.6˚F warmer than the next closest decade, 1990-1990, which averaged 44.9˚F. 

If was also 4.4˚F warmer than the average march temperature for the entire period of record (1875–2019), which was 42.1˚F.  

This time of year, it takes about 13 days for the average temperature to increase 4.5˚F.  For example, the average temperature on March 2 is 39.5˚F and by March 15 it is 44.  Thus, the 4.4˚F warmth during the past decade is the equivalent of spring coming about 2 weeks earlier than the long-term average.  The difference compared to the relatively cool 1950s and 1960s is even larger.  Those people must have been wondering if spring would ever come!

So, over the past decade, March has been more of a lamb than a lion.  What happens in any given year is still strongly dependent on the whims of the jet stream and any decade on slow variations in the large-scale circulation, but we're starting to head solidly into abnormally warm territory.  My money is on seeing a greater frequency of warm March's as we move forward through the 21st century and that we won't see a decadal average below the 1875–2019 average of 42.1˚F ever again.

Thursday, March 5, 2020

Spring Has Sprung

Yesterday's (Wednesday) high of 60˚F was the third 60 degree day of the calendar year, tying Feb 28 and 29 for the warmest temperature of the year so far. 

We will eclipse that today, with the NWS going for a high at the airport of 63˚F.  I'm planning to go for a sloppy and slow skate ski at Mountain Dell later today as the skiing there is now officially on life support and probably won't last much longer. 

The forecast over the next several days suggests continuation of a spring-like pattern, although precipitation will be moving in over the weekend. 

Mild conditions will prevail through Saturday.  Today will be bluebird and spectacular.  Tomorrow (Friday) will also be nice, although there may be some inconsequential wispy high clouds at times and moderate southerly flow at upper elevations. 

Saturday is a clear transition day with periods of high clouds and strong southwesterly flow in advance of an approaching trough and cold front, as depicted below in the GFS. 

This is the type of pattern that can result in significant snowpack sublimation.  It will be interesting to see if we see a small decrease in snowpack water equivalent at some of the SNOTEL sites.  It might also be a bit early for this to happen, but blowing dust is a possibility if emission sources in southern and western Utah are ready to be active. 

Although the approach of a front is sometimes cause for excitement, in this case, the system sort of peters out and we get just some remnants with no real wind shift to northwesterly at crest level.  We then see a period of southwesterly flow with dribs and drabs, before a closed low finally decides to move inland toward the middle of next week.  To try and summarize this mess, below is the GFS 500-mb and 3-h precipitation forecast from 1200 UTC (5 AM MST) Saturday 7 March through 1200 UTC (0600 AM MDT) Wednesday 11 March.

The entire period is relatively mild (although not as warm as today), so precipitation will most likely be in the form of rain on the valley floor.  In the mountains, NAEFS forecasts show dribs and drabs of snow for upper Little Cottonwood.  The ensemble mean for the entire period through 0000 UTC 12 March (6 PM MDT Wednesday) is around 15 inches, although this is skewed by a small number of big outliers.  My view is that we get a few inches here or there and that the most likely total for the entire period is in the 6-15 inch range. 

Given my philosophy that low expectations are key to a happy life, I prefer to go into a situation like this thinking that we're not going to get a lot of snow and hoping that we end up on the upper-end of expectations. 

Wednesday, March 4, 2020

Challenges of Science Communication in the 21st Century

Meteorologists like myself are on the front lines for science communication every day.  What other science profession has one of the most watched television channels (The Weather Channel), several minutes dedicated to the science in local news broadcasts, smart-phone apps, etc.?  We are on the public's "radar" every day.

So I've been watching the communication, response, and reaction to COVID-19 with more than a passing interest.  I see many of the similar issues at play for epidemiologists, health professionals, government agencies, politicians, and the public as we have prior to, during, and following high-impact weather events.

Many of the challenges that exist are not new.  First, scientific literacy is relatively low.  As noted by Carl Sagan:
"We live in society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology."
Second, there is strong anti-intellectualism in the United States, which was well described in a Newsweek article by Isaac Asimov in 1980:
"There is a cult of ignorance in the U.S., and there always has been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life."
As discussed in a 2011 article by Dane Claussen, this anti-intellectualism originates from several veins including religious (e.g., creationism), populist skepticism/distrust of experts (e.g., anti-vaccination), and practical (i.e., knowledge isn't important unless it leads to immediate material gain).

Finally, we have biases that we all suffer from including confirmation bias — the tendency to search for, interpret, favor, and recall information in a way to confirm our preexisting beliefs — and tribalism — a way of thinking in which we are loyal to a social or political group.

Although not new, these challenges have evolved in a dangerous way in the digital era.  As noted by Del Vicario et al. in a 2016 article in the Proceedings of the National Academy of Science:
"Digital misinformation has become so pervasive in online social media that it has been listed by the [World Economic Forum] as one of the main threats to society...Most users tend to select and share contact related to a specific narrative and tend to ignore the rest"
A few additional perspectives based on my meteorological experiences and observation of the COVID-19 situation.

1. The dissemination of information is not linear.  In weather the National Weather Service and diseases the Center for Disease Control serve as "expert" sources for information and through their various partners (e.g., FEMA, Homeland Security, various emergency management groups, health organizations, etc.) ideally attempt to distill a consistent, evidence based message of the situation and response.  However, they do not control the narrative and in the modern digital age, people get their information from all sorts of nebulous sources of varying quality.  In some instances, these sources are nefarious.  This is why, when it comes to hazardous weather, I consistently preach the importance of relying on forecasts from the National Weather Service and the recommendations of emergency management groups.  Weather forecasting and epidemiology are not exact sciences and uncertainties exist, but the best course of action is to ignore the echo chamber and go to the most reliable sources of information.

2. Leadership matters.  Although nobody really controls the narrative, the President can strongly shape it.  Nobody recognizes this better than our current President, who has forcefully manipulated the media for years.  His contradictions of disease experts greatly fuel conspiracy theories and open windows for nefarious parties to feed the public false narratives.

3. The poor and vulnerable will suffer the most.  During natural disasters, the poor and vulnerable have the least capacity to take action and often pay the greatest price.  They have the least capacity to flee a hurricane, for example, and often live in homes or apartments (or cars) that are more vulnerable to winds and flooding.  Similarly, those less advantaged have less capacity to sit through a quarantine, work from home, pay for daycare when schools close, or seek appropriate medical treatment if they lack sufficient health insurance.

4. Plan for the worst, hope for the best.  Weather forecasting is not an exact science and as a result, a range of outcomes are possible with a potentially hazardous weather event.  One needs to consider the range of possible outcomes, including worst-case scenarios.  If there's a 10% chance of a 30 foot storm surge, one needs to prepare for that eventuality.  If the surge ends up being 15 feet, we're grateful.  COVID-19 is a new infectious disease making the rounds.  If we get our arms round this disease and can keep it contained, that's a victory, not a reflection of overhyping by experts.

Monday, March 2, 2020

Quiet Work Week Ahead

Forecasts point to a fairly quiet work week with the storm-track to our north and high pressure in control. 

The NAEFS ensemble shows flat-line conditions (i.e., no precipitation) through the work week and then a lot of uncertainty about what will happen as the next trough moves into the western U.S. for the weekend. 

Temperatures look to be on the rise each day and will be quite mild near the end of the week.  Below is the NWS forecast for Salt Lake City.

Mountain Dell Nordic skiers should get out this week as I suspect it will be difficult to keep things going there after this coming weekend. 

The dry week also means losing additional ground relative to climatology in the upper-elevation snowpack race.  I've mentioned previously that things are not a lock for an above average spring runoff statewide and a look at the latest SNOTEL observations shows a somewhat mixed bag.  The central Wasatch and Oquirrhs have most sites at or above 90-100% of average for early March, but elsewhere, there are quite a few stations running below 90%. 

Thus, what happens from here depends strongly on the weather over the next 4-8 weeks.

Consider for example Parley's Summit.  That SNOTEL is actually just above peak median, which usually comes around April 1st.  Ideally, what happens from here is that it continues to accumulate snow and then the melt occurs quickly, maximizing runoff and reservoir recharge.  This is what happened last year (green line). 

On the opposite extreme, the spigot turns off and we warm up.  The melt occurs more slowly and the runoff is less efficient.  More snow is lost to sublimation. 

Even upper elevations remain vulnerable.  Snowbird at present sits at 37.1 inches of water equivalent.  This is well above median for the day (27.7 inches) and just a shade behind last year (37.3 inches). 

However, Snowbird is still behind peak median, which is 43.1 inches on May 1st.  Ideally the snowpack peaks then and we have an efficient spring runoff.  However, if the spigot shuts off early, we don't reach the median peak and the runoff is less efficient. 

The next few weeks it will be interesting to watch how things evolve.  Is this week a harbinger of things to come or a temporary week of spring fever?  Time will tell. 

Thursday, February 27, 2020

Wither Nordic Skiing?

When it comes to the impact of global warming on snow, there will be few (if any) winners but some will suffer more than others.  Lower elevations are generally more vulnerable than higher elevation areas since temperature decreases with height.  For a given increment of warming, lower elevation regions see an event greater fraction of precipitation fall as rain, more and more substantial snow loss events, and greater loss of shoulder-season snowfall and snow compared to upper-elevation regions.

The vast majority of Nordic (i.e., cross country) ski centers and public trails are located in valleys and at relatively low elevation.  Thus, Nordic skiing is and will be suffering more than Alpine skiing, especially in ski regions where there is great vertical relief, such as Utah and the European Alps. 

For the most part, this has been a dismal Nordic ski season in Europe, including the Alps and Scandanavia.  Most of the Nordic races I've watched have featured snow only at the venue or only at the trail.  Below is an example from Falun, Sweden in early February. 

Source: NodicFocus
A big reason for this is exceptional warmth in Eurasia.  In January, for example, the biggest warm anomalies globally were in north-central Eurasia, although western Europe was also well above average.  
Numerous warm records have fallen this winter, including the highest temperature ever measured in Scandinavia in any winter month

Extreme warmth of this type reflects both natural variability and global warming.  The dice in our warming climate are increasingly loaded to roll above average temperatures and warm extremes.  Anomalous cold can occur, such as Alaska during January, but the odds of that is decreasing and note how much of the planet is in the red in the plot above (and this is based on a 1981-2010 base period – it would be even redder if we used a 30-year base period from the early or middle 20th century).

In Utah, with the exception of Solitude, cross-country ski areas are located generally at low elevation.  For example, North Fork Park, Mountain Dell, and Soldier Hollow are below 6000 feet.  Round Valley, White Pine, and Jeremy Ranch are below 7000 feet.  We've had a good Nordic season this year, but these are elevations with vulnerable snow climates.  There will still be year-to-year variations in snow conditions, but I fear in the coming decades, we will find that the number of days of viable Nordic skiing in these areas will be on the decline, and that will be a damn shame. 

Tuesday, February 25, 2020

Transformative Student Experiences in Alpine Meteorology: REALM

Excitement is running high in my department as we prepare to host the Research Experiences In ALpine Meteorology (REALM) program this summer.

REALM is a National Science Foundation sponsored Research Experiences for Undergraduates (REU) program designed to enable the active participation of undergraduates in research.  What is unique about REALM is its focus on mountain weather.  We have received applications from students with diverse backgrounds from all over the United States.  Those accepted into the program will have an opportunity to learn and recreate in the mountains of Utah, which I expect will be transformative for many.  I personally remember my first trip to Utah when I was 16 years old and how our trip up Little Cottonwood Canyon further kindled my interest in mountain weather and winter storms.

Support from the National Science Foundation and University of Utah provides ten students with lodging, travel funds, and a stipend.  From late May to early August, these students will be in residence at the University of Utah and conducting research with faculty in the atmospheric and related sciences; developing professional communication, leadership, and teamwork skills; and gaining new understanding of mountain weather and climate.

Interest in the program is incredibly high.  We have received 145 applications from outstanding students!

Donor support can greatly enhance the REALM program.  Here are a few examples:
  • $100 pays for a weekly lunch with presentations by faculty, post-doctoral researchers, and graduate students within the Department of Atmospheric Sciences.
  • $200 provides prizes for year-end poster sessions.
  • $400 provides meals at Silver Fork Lodge for REALM orientation day.
  • $600 hosts a networking and socializing event with other STEM-related REU programs on campus such as those in Physics and Astronomy, Chemistry, and Material Sciences.
  • $3,000 covers student travel to Storm Peak Laboratory in Steamboat Springs, Colorado, a high elevation atmospheric research facility, including a visit to an air-quality monitoring site in the oil/gas fields of the Uinta Basin.
  • $10,000 enables REALM to admit an additional student into the program.
Gifts of any amount are greatly appreciated.  Please consider making a contribution today to help provide students with a transformative research experience.  Contributions can easily be made via the giving page for the University of Utah Atmospheric Sciences Department at  Simply indicate your desire for your contribution to be directed to REALM in the special instructions box.

Monday, February 24, 2020

The Overnight Blow

Strong winds accompanied a cold front that moved through northern Utah last night.  In my neighborhood, it's garbage pickup day and there were many tipped cans and much garbage strewn about, not to mention bleary-eyed people who were awoken in the night by windows rattling. 

The strong winds came in the northwesterly flow following the frontal passage.  Peak gusts at the Salt Lake City International Airport (41 mph) occurred at about 0820 UTC (0120 MST).  The situation shortly after that at 0900 UTC (0200 MST) when I was awoken by the storm is shown below and illustrates the widespread northwesterly postfrontal flow. 

A quick look at the overnight observations shows many valley sites recorded peak gusts of over 50 mph.  The peak gust in the Salt Lake Valley appears to be 59 mph on the Baccus Highway (SR 11) near 6200 South (a somewhat elevated location on the west bench.  The University of Utah reached 50 mph on the top of the 8 story William Browning Building. 

It was nuking in the mountains as well.  While ridgetop gusts hit 100 mph at one location in the central Wasatch this morning, most notably, there was a 73 mph gust at Parley's Summit, which is quite impressive for that location.

By and large, my impression is that we didn't do a great job letting people know it was going to blow as hard as it did.  It's easiest for me to go back and look at NWS forecasts as they are archived and the zone forecast issued for the Salt Lake and Tooele Valleys at 304 PM yesterday afternoon has no mention of wind.

That being said, the NWS area forecast discussions did mention the potential for gusty winds behind the front, but I think overall we (i.e., the weather community) could have perhaps done a better job of indicating the strength of the gusts.  I think people were surprised, although in the end, these don't appear to have been damaging winds in the lowlands. 

Meanwhile, as of 8 AM, Alta-Collins has picked up 3 inches.  However, we'll see some snow showers through tonight.  My guess is another 2-4 inches.  Do your snow dances as this is it through at least Saturday.

Sunday, February 23, 2020

Sunday Tidbits

A few tidbits today for your Sunday reading.

Lone Peak Wilderness

Is there a more spectacular near-urban wilderness in the contiguous United States as spectacular as the Lone Peak Wilderness? 

It's a rugged place, with much of it more accessible in winter and spring than summer and fall. 

Yesterday near White Baldy
Hard to believe there was talk at one time of putting a tram up the iconic Pfeifferhorn.  Thankfully that never happened.  

Wasatch Oddities

One of the curious aspects of the central Wasatch Mountains is that the highest terrain isn't on the mountain "crest" or hydrologic divide like it is in the northern Wasatch, but west of it.  A good example of this is provided below, looking north from upper Red Pine Canyon at the high ridgeline above Little Cottonwood.  Note how the terrain is highest from Twin Peaks on the left (west) to Monte Cristo Peak center right, and then descends as one moves further east to the Emmas and environs above Alta.  

I've often wondered what the ramifications of this topographic configuration are for winter storms. 

Not Out of the Woods Yet

I've been hearing a lot about what a good snowpack we have and how this bodes well for the spring runoff, but as I've suggested in previous posts, we're not out of the woods yet. 

It's important to recognize that we have some basins in central Utah that are running near or somewhat below median.  In other areas, many basins are above but not way above median. 

Additionally, it is only late February.  We still have one to two months of snow accumulation season left, depending on elevation.  Much is going to depend on the weather over the next 4 to 6 weeks.  Further, we live in a warmer climate now and while that does not prevent us from having a cold and snowy March and April, we need to recognize that the dice are becoming loaded in a way that we are going to see more springtime snowpack ablation (loss) events and less efficient runoff and reservoir recharge.  Thus, a near median snowpack in late February today doesn't provide as good of odds for a near average spring runoff as 40 years ago.   

Friday, February 21, 2020

NOAA Computer Upgrade

NOAA has announced an upgrade to its computing resources for weather and climate prediction. 

The full press release is available at  The upgrade consists of two Cray computers, each with a capacity of 12 petaflops (typically two identical systems are used in weather computing to ensure redundancy and operational reliability).  A petaflop is one quadrillion floating-point operations per second. 

The NOAA press release suggests that this will keep the agency on par with leading weather forecast centers around the world.  It will help, and it will lead to improved forecasting for the United States, but I'm not sure it will enable us to get on par with ECMWF, at least in terms of global weather prediction.  In January, the ECMWF signed a contract in January that is estimated to provide two computers, each estimated to have a capacity of 20 petaflops.  Given that the ECMWF focuses on global prediction (and runs fewer modeling systems), this will likely mean they will be able to dedicate more horsepower to their global forecast system.  Additionally, the UK is apparently spending $1.5 billion for a new supercomputer for weather and climate forecasting, although it's unclear how much of this will go to operational numerical weather prediction. 

My view is that this is a positive step forward, but the US would benefit greatly from greater investment in computer infrastructure for operational numerical weather prediction. 

Thursday, February 20, 2020

What an Airmass!

Sunrise view this morning in the Avenues
You'll be hard pressed to find a more spectacular airmass than the one resident over northern Utah this morning.  Not a cloud in the sky and unlimited visibility.  Simply spectacular!

Under clear skies this time of year, one might expect a large difference between the maximum and minimum temperatures, but that hasn't been the case at the Salt Lake City Airport.  Yesterday's maximum was 36˚F and the overnight minimum was only about 21˚F (it might go slightly lower than that).  That's a 15˚F range, which is smaller than average (19˚F) for this time of year.

Source: MesoWest
Tour our southeast, the Rush Valley south of Tooele can often get quite cold, and last night it got down to about 6˚F.  That's impressive compared to Salt Lake City, but still only 28˚F cooler than yesterday's max.  Here too, the daily range of temperature is a bit subdued despite the clear skies.

In contrast, if we go east of the Wasatch, temperatures are really bottoming out and we're seeing large daily temperature ranges.  The ultimate is of course Peter Sinks where it has been below -43˚F the last two days and where it got down to -48˚F yesterday.  I kid you not!

Source: MesoWest
The sinks have always been a bit of a meteorological oddity.  Nobody lives there, so such temperature extremes are fascinating but not all that important for human activity.  However, when it is cold there, it is often cold in places like Randolph, which is east of the Bear River Range near the Wyoming border and indeed temperatures last night at one station fell to just below -25˚F. 

Source: MesoWest
Finally, how about the Park City area and the Cottonwoods?  The situation this morning is simply spectacular if you are a lover of valley and basin cold pools.  -11˚F at Kimball Junction and -9˚F at Silver Creek Junction and along SR-224.  That's a cold start for skiing, but check out how the temperatures increase with elevation, reaching the 20s at some upper-mountain locations. 

Source: MesoWest
Big Cottonwood is also remarkable with -8˚F at Reynolds Flat an 22˚F immediately above it on the summit of Reynolds Peak.  Dawn patrollers in that area must have had an interesting climb into the warmth this morning.  

To summarize, a spectacular airmass is in place, but the daily temperature range, relative to climatological expectations, is a bit subdued west of the Wasatch.  A clue as to why is provided in the MODIS satellite image from yesterday.  Note the lack of cloud cover along the Wasatch Front and valley locations west, whereas there is extensive cloud cover over and east of the Wasatch.  

If it was snow covered in the Salt Lake Valley, we probably would have been much colder last night.