Sunday, August 19, 2018

Trip Report: Teton Crest Trail

It has been about a 30 year dream of mine to backpack the Teton Crest Trail and with a little help from a willing back and a friendly Grand Teton National Park climbing ranger, we were able to do it this past week. 

The seeds for the trip were planted when I was a teenager and my family made our first visit to Grand Teton National Park.  I remember riding the boat across Jenny Lake with a group of college-age backpackers and thinking I want to be them some day. 

After graduating college, I drove across the country and spent several days in Jackson in late May 1989.  I was 22 years old, short on experience, but long on exuberance.  Or perhaps what Allen Greenspan would call irrational exuberance.  I walked into Teton Mountaineering when I arrived for some beta and someone sold me an ice axe, told me to learn how to use it, and said good luck.  Said ice axe is in the photo below, taken in the North Fork of Cascade Canyon, May 1989.


The next year, I returned to the Tetons with Dave Schultz, a good friend from graduate school who is now a professor at the University of Manchester in England.  We did a number of day hikes, including one to Paintbrush Divide. 


It was during these trips that I began to dream of hiking the Teton Crest Trail.  Finally, last week it happened, and it exceeded expectations.  What an incredible variety packed into 4 days and 40 miles.  A few photos are below.

We started with a major cheat, beginning from the top of the JHMR tram.  They charge $43/$35 per person (walk up/advance reservation) for the privilege!  I'd call it highway robbery, but saving nearly 4000 vertical feet of ascent
with full packs was desirable given the time available and my balky back.   

Just another Teton meadow.

Our sole moose sighting.

Heading northbound near Fox Creek Pass with distant views of the Grand and surrounding high peaks.

Smoke tinged sunset from our first night's campsite.

Sunset Lake.

Wildflower carpet above Sunset Lake.

Point-and-shoot photos don't do it justice.

After meandering for two days through meadows and enjoying wildflowers, things get real when you hit Hurricane Pass, gape at the Tetons, and descend into the upper South Fork of Cascade Canyon.  From here, you are in the big mountains. 

Well deserved rest the next day while ascending the North Fork of Cascade Canyon.

Lake Solitude in the North Fork of Cascade Canyon.  

View of the Grand Teton on the ascent to Paintbrush Divide.  There are a few places in the lower 48 that remind me a great deal of the Alps with the big relief and the huge glacier carved canyons and this is one of them.  The others are in the North Cascades.

Paintbrush Divide, 28 years since my last visit.  Maybe we'll return for the 30th.

One of the great things about the Teton Crest Trail is that it is remarkably well designed and built with low grades the entire route, which is just what you want carrying a big pack.  The only steep section is here, right below Paintbrush Divide, where a persistent snowfield often requires one to use an ice axe, although trail through this area was snow free, following a path at the top of the scree field.

Fortunately, we did hit a bit of snow that required crossing as it would have been a shame to be in the Tetons without a little snow travel.

Monday, August 13, 2018

Deep Convection and Haboobs

Over the past few days I've travelled to and from Tempe, Arizona where we dropped my daughter off for her freshman year at Arizona State.

It was a pretty exciting period meteorologically.  The first night, we experienced 60+ mph outflow winds from thunderstorms approaching Phoenix from the Mogollon Rim to the northeast, which then provided a great lightning show.  The next night, incredibly, I slept through 3+ inches of rain that fell in Tempe in a huge deluge.

My daughter texted me late yesterday saying they had just had a haboob, that the power was out, and she was holed up somewhere on campus until the storm passed.  A haboob is a dust storm that is frequently initiated by the outflow from thunderstorms and typically found in desert regions of the world.

For yesterday's haboob in Phoenix, a quick look around YouTube unearthed the video below that is available here and I hope is accurate for the date and time.  Note in particular the deep convection on the right of the frame, with the outflow and concomitant dust running well away from the storm.

Imagery from the KIWA radar operated by the National Weather Service shows the evolution very well.  The leading edge of the outflow and haboob, known as a gust front, is indicated by an arc shaped "fine line" that moves southwestward across the Phoenix Airport (red square) well in advance of the thunderstorm that produced it.


Passage of the gust front is easy to spot in the meteogram from the Phoenix airport.  Note the abrupt 20˚F drop in temperature and increase in sustained winds to 45+ mph with gusts to 58 mph.


The fine line enables meteorologists to track features like this and provide very good short-range forecasts of hazardous wether in conditions like this.  The fine line is produced by radar returns not from precipitation, but instead from what meteorologists refer to as "nonmeteorological" scatterers or targets, such as bugs, dust, sand, and the like.

Modern radars collect statistics on radar pulses that allow meteorologists to identify non-meteorological scatterers.  Non-meteorological scatterers tend to produce complex radar scattering signals that show lower correlations from radar pulse to radar pulse compared to precipitation.  As a result, a product known as correlation coefficient is produced by National Weather Service radars that can be used to discriminate between non-meteorological scatters and precipitation.  Below is the correlation coefficient analysis for the radar scan collected right after the passage of the fine-line past the Phoenix Area.  Values accompanying the thunderstorm are near 1 (red), whereas those accompanying the fine line are lower (.8 to .9, light blue, green, and yellow).


Haboobs provide an excellent example of how thunderstorm impacts can occur at a great distance from the storms themselves.  Thanks to modern technology, I found warnings from the National Weather Service, which appeared in a timely manner on my phone, were extremely helpful while we were traveling across Arizona. 

Wednesday, August 8, 2018

My Seasonal Outlook

The Silly Season is upon us when prognosticators spouting an alphabet soup of climate phenomena (e.g., ENSO, PDO, NAO, etc.) make claims for what this ski season will be like.

As far as northern Utah is concerned, ignore all this crap.  The correlations are low.  The useful skill is non-existent.  Yeah, I know there is a 70% chance of El Nino.  Who cares.  Nobody knows what kind of ski season the Wasatch are going to have.  Nobody.  This is why I call it the silly season

Here's my official forecast, previewed on twitter a couple of weeks ago.


There, I feel better now.

Sunday, August 5, 2018

Smoke Filled Weekend

Yesterday's imagary from the Suomi NPP satellite shows how northern Utah has been in the crosshairs of plumes from fires further upstream, especially California. 


PM2.5 concentrations at Hawthorne Elementary have been in the moderate to unhealthy for sensitive groups categories for about 48 hours, and in the moderate category at times for several day before that. 


This is one of the worst stretches of smoke that I can remember and I've developed a persistent cough in the last couple of days. 

Dry, clean, cool air is desperately needed!

Friday, August 3, 2018

Contrasting Heat Waves: July 1960 vs. 2018

Motivated by an intriguing tweet by University of East Anglia Professor Tim Osborn, I thought we would compare global temperatures for July of 1960, which was the warmest 20th century July at the Salt Lake City International Airport to July of 2018, which was the 5th warmest on record and also feature remarkable temperatures in many regions across the Northern Hemisphere. 

The graph below illustrates the anomalous warmth of July 1960 as well as the recent string of very warm Julys in the 21st century. 

Source: NOAA Regional Climate Centers
For convenience, I am going to examine the surface temperature departure (or anomaly) from the 1981-2010 average from the NCEP/NCAR reanalysis for the two Julys.  There are better datasets for doing a surface temperature comparison, but the differences are not going to be all that significant.

In July 1960, anomalous warmth covered much of the western continental U.S. and southwest Canada, with the most anomalous temperatures along the US-Canadian border.  Elswhere, one sees a mixture of both cold and warm anomalies with Most of southern and central Europe and central Asia being cold and far northern Europe warm.  By eye, it appears that overall the Northern Hemisphere is probably a bit cooler than the 1981-2010 climo, which is what we would expect given the global scale warming that has occurred since 1960.

Source: NOAA/ESRL
In July 2018, we see a different story.  Not surprisingly, anomalous warmth exists over the western U.S., but not the dominance of warm anomalies elsewhere, including maxima in Scandanavia, North Africa, and central Asia.  Cold anomalies are more localized.  

Source: NOAA/ESRL
This is consistent with the warming that has occurred in recent decades, which has stacked the deck for warmth, so that longer, more severe heat waves are more likely.  

Tim Osborne's tweet went a step further than my simple analysis, however.  He compared the 1976 and 2018 heatwaves in the UK (relative to the 1960-1990 average, which is 20 years sooner than the plots above), but then examined what would happen based on climate projections for 2070 and scenarios in which greenhouse gas emissions peak in 2080 (RCP6.0) or are aggressively reduced to limit the global average temperatures to less than 2˚C above preindustrial.  In either case, we have more warming in the pipeline and are facing a hotter future with longer, more severe heat waves.  How much hotter depends on future greenhouse gas emissions.  

Source: @TimOsbornClim (https://twitter.com/TimOsbornClim/status/1023950044234502144)
This is why "Normal Is Gone Forever".  The future climate is dramatically different from the one you grew up with.  

It should be noted, however, that the emergence of climate shifts depends on the variable.  Detectable and significant shifts in temperature are early "emergers".  Shifts in other variables, like snowfall and snowpack are occurring, but may emerge more slowly in some regions compared to others (e.g., declines in snowfall and snowpack may occur later or more slowly in colder regions than warmer regions).  For more discussion of this, see our August 2013 posts Western Snow Trends and Global Warming Part I and Part II.

Wednesday, August 1, 2018

July in the Rear View Mirror, Thankfully

A little something to get you going on this August 1st as we put July in the rear view mirror and begin to look forward to cooler times.


The weather this July can best be described using words like ugly and heinous.  

At the Salt Lake City International Airport, the mean temperature for the month was 83.1˚F, tied for 5th warmest all time.  
Source: NOAA Regional Climate Centers
And here's a factoid for you.  The 11 warmest Julys have all happened in the 21st century.  People in Salt Lake simply didn't suffer like this in the 20th century.  If you go back to Y2K, the hottest July on record was 81.2˚F (1960).  Now, it is 85.3˚F (2017). 

Source: NOAA Regional Climate Centers
Digging in beyond the mean monthly temperature, the mean maximum and mean minimum for the month were 95.5˚F and 70.7˚F, respectively.  The former only rates as the 14th warmest on record, but the latter is the 3rd warmest.  Minimum temperatures are a big driver of comfort as they allow for cooling of the home and good overnight sleeping weather.  Sadly, this July saw a very high mean minimum temperature, 21 days with a minimum temperature 70˚F or higher, and a run of 13 consecutive days (5-17 July) above that threshold.

It is interesting to compare July 2018 to the hottest July in the 20th century, 1960.  1960 featured a mean temperature of 81.2˚F, 0.9˚F cooler than this July, but the average daily temperature range was much larger with maximum and minimum temperatures of 98.2˚F and 64.2˚F, respectively.  I suspect 1960 would have been far more comfortable as a whole due to the lower minimum temperatures.  

How about precipitation?  It was scant.  The total for the month was 0.19 inches.  That rates as the 34th driest out of 145 years, so not exceptionally dry, but dry nonetheless.  If you are wondering, there have been four Julys with only a trace, so it is possible to get "shut out" or at least nearly shut out.

For the summer to date (i.e., 1 June - 31 July), we've had 0.24" of precipitation, which rates as the 11th driest.  I've noticed that virtually nothing is growing in my gardens and I've mowed my grass about once in the past 6 weeks.  I try to water at what I consider to be a minimum plant survival level and little rain and the heat, it appears I'm right on that level. 

July is the month with the smallest amount of year-to-year variability in temperature in Salt Lake City.  If one looks at the chart above and does an eyaball, there's about a 5˚F range in mean temperature for the month, with a few outliers.  One of those is 1993 when the mean temperature was 69.9˚F (and the mean minimum temperature was and incredible 56.1˚F).  I have a dream that July 2019 is the new July 1993. 

Tuesday, July 31, 2018

Differences Between Winter and Summer Air Pollution Episodes

There are dramatic differences in air pollution episodes over the Salt Lake Valley between winter and summer.

During winter, when the sun angle is low, we frequently lack sufficient surface heating to warm the atmosphere and develop a deep layer in which turbulence can mix the near-surface air with the atmosphere aloft.  The layer in which that turbulence occurs, which is known as the boundary layer (or mixed layer), can be very shallow.  As a result, emissions from our urban area are trapped in the valley, leading to elevated particular matter concentrations.

An example is the inversion event of late December 2016.  As can be seen in the photo below, taken on the afternoon of 30 December, smog is confined primarily to the valley and the visibility improves dramatically with altitude.  Typically in these instances, one can find clean air simply by going to the mountains.


A sounding taken that afternoon at the Salt Lake Airport is very typical of of wintertime pollution events and features a very shallow boundary layer that extends from the surface to about 850 mb, which equates to about 300 meters (1000 feet) of depth, roughly consistent with the depth of smog above.  At the top of the boundary layer is a strong inversion in which the temperature increases very dramatically with height nearly 15ºC from about 850 to 800 mb (about 500 meters).


That inversion essentially puts a lid on the valley atmosphere.  In the winter, we have met the enemy and it is us.  We can't really blame our pollution problems on anybody else.

In the summer, the situation is much different.  The sun angle is high and there is strong heating of the surface and lower atmosphere, which leads to a deep boundary layer and turbulent mixing.  In contrast to winter, when the pollution is confined to near the valley floor, it can be much deeper.  For example, the photo below from Snowbird's Hidden Peak cam was taken yesterday.  Smoke and pollution extend to and above mountaintop levels and the Oquirrh Mountains to the west are obscured.

Source: Snowbird
The sounding taken at the Salt Lake airport yesterday afternoon is very typical of summer in northern Utah.  Very near the surface to about 850 mb, temperature decreases very rapidly with height, more than 1˚C per 100 meters.  Such a layer is called superadiabatic and the air density in such a layer actually increases with height rather than decreases.  Basically, the near-surface atmosphere is being heated so intensely that the turbulence can't mix the atmosphere fast enough to keep that layer at a constant density. 


From about 850 mb to 750 mb, the temperature decreases at about 1˚C per 100 meters.  Such a layer is known as dry adiabatic and the air density in such a layer is constant with height.  Turbulence has little trouble mixing through such an atmosphere and this is why we see smoke, haze, and pollution through such a deep layer.

There is a very weak stable layer at about 750 mb that might cap the turbulence, however I suspect at times strong thermals penetrated to greater heights than that.  The paragliders will know.

So, unlike wintertime pollution episodes, during the summer, we have mixing through deep layer.

Another difference is the pollution sources.  Long-range transport plays a role in the summer.  Yesterday afternoon's MODIS image shows several major fires over the western U.S.  Smoke and trace gases from those fires are being transported into our area.  There is probably no single fire that is producing our smoke.  Some of it is long-range transport from California, Oregon, and possibly Idaho, and some might be coming from the Goose Creek Fire along the Utah-Nevada border.  There are some smaller fires in the vicinity that might serve as local sources in some areas.

Source: NASA
The smoke and trace gases then combine with local emissions over the Salt Lake Valley.  Much of the PM2.5 is probably due to long range transport, with some local production.  In the absence of the smoke, PM2.5 values would probably be "good" during this period.  On the other hand, ozone can be elevated even without the smoke, and sometimes the trace gases in the smoke interact with local emissions to elevate ozone further.

Over the last five days, PM2.5 at Hawthorne elementary has been on the boundary between good and moderate levels.  This is somewhat higher than we would expect this time of year in the absence of smoke.  Ozone shows a stronger diurnal cycle, poking up into moderate values on some afternoons, occasionally approaching the cusp of unhealthy for sensitive groups.


In a situation like this, the mountains do not necessarily provide a reprieve from the pollution.  It is even possible in the afternoon that ozone is higher than in the valley (this reflects transport and air chemistry that I don't have time to get into today).  In patterns like this, I typically exercise in the morning when ozone concentrations are typically lower.  

Monday, July 30, 2018

Normal Is Gone Forever

"The old records belong to a world that no longer exists"
- Dr. Marty Hoerling, Research Meteorologist
NOAA Earth Systems Research Laboratory

It has been a remarkable summer across the Northern Hemisphere, with high-temperature records being set at locations in North America, Asia, Europe, and North Africa.  Now that we are well into the fire season, a pall of smoke generated by large wildfires hangs over much of the western United States, as evident in yesterday afternoon's GOES-16 satellite image.  

Source: CIRA
Will we ever return to normal?

No.

Although the climate, especially on regional scales, has always exhibited variability, we are now accelerating into a future in which the planet will be warming at a rate not seen since the emergence of human civilization. 

Further, while this warming may occur in fits and starts rather than at a steady rate, the idea that what we are currently experiencing is "just a cycle" is pure fantasy.  We will also not settle around a "new normal" for at least the next few decades, and even that assumes we get our greenhouse gas emissions under control quickly.  

The reality is that we have poked the climate bear with a hot poker and it is not going to calm down anytime soon.  If we curtail greenhouse gas emissions dramatically, perhaps we can get this thing under control in the latter half of the 21st century, but right now, that's looking unlikely.  

So, it is time that we all get used to a world of remarkable change, that we give up on the idea of a stationary climate, and we rise to meet the challenge posed by rapid change.  

If you want an example, look no farther than the western U.S. wildfires.  Yes, the lack of precipitation this past winter probably wasn't due to global warming and wildland management, development patterns, and climate variability have contributed to the mess we're in, but the fingerprints of climate change are in the ashes.  Global warming is shifting the weather in ways that we are seeing longer fire seasons, increased fuel aridity, increased acreage burned, and more extreme fire behavior (see, for example, Abatzoglou and Williams 2016).  

And here's a sobering thought.  The train has just left the station.  The fire season of the future is longer, hotter, and drier.  If you think 2018 is bad, fast forward to a drought period around 2048 or 2078.

Normal is gone forever.  The sooner we accept that and build a weather and climate resilient society for the future, the better.  

Friday, July 27, 2018

The Catastrophic Carr Fire

Thermal anomalies (red) and smoke from the Carr Fire as seen from Aqua/MODIS 26 July 2018
A catostrophic situation is unfolding in northern California where the Carr Fire is threatening communities in and around Redding.

The latest incident information from Cal Fire indicates that as of 9:17 AM this morning (27 July), the Carr Fire has burned 44, 450 acres, destroyed 65 structures, and damaged 55 structures.  Only 3% contained, the fire is currently threatening almost 5,000 structures, with numerous evacuations and road closures.  News reports indicate that the fire has now claimed the lives of two firefighters.

News footage of the fire is simply unbelievable.  Below are a couple of perspectives on rotating updrafts associated with the fire.


The rotation was clearly evident in Doppler velocity imagery from the Beal Air Force Base, posted by U of U mountain meteorology alum Neil Lareau.  In this image, red indicates flow away from the radar, which is to the south, and blue flow towards the radar.  In this case, the radar is sensing ash, not precipitation. 
Redding is a hot place in summer, but the situation right now is inferno like.  The average high for yesterday and today is 100ºF at the Redding airport a bit southeast of the fire.  Yesterday it hit 113˚F, a new record for the day, with a relative humidity that dropped below 10%.


Winds have not been as insane as they were during the Tubbs Fire that affected Santa Rosa, but looking at stations around the area, I can find locations with wind gusts to 20 mph yesterday afternoon.

Forecast highs for Today through Monday are 110˚F, 110˚F, 109˚F, and 107˚F. 

Thursday, July 26, 2018

Smoke in Salt Lake, Misery in California

This morning dawned with smoky skies and a fairly orange sun that wasn't well captured by my cell phone camera while looking up City Creek Canyon from the Bonneville Shoreline Trail. 


Although the perspective is a bit oblique, I love looking at the beautiful GOES-16 imagery from CIRA.  Smoke covers a large portion of central and northern California, northern Nevada, southern Oregon, and southern Idaho.  There's some that has snuck into northern Utah as well. 

GOES-16 imagery from CIRA at 1507 UTC 26 July 2018
The purple air network shows moderate or worse air quality across much of that area (sadly with few observations in Nevada). 

Source: PurpleAir, 9:35 AM MDT 26 July 2018
Those of us in northern Utah shouldn't complain.  The misery index in California is off the scale.  In addition to smoke and associated poor air quality, high temperatures in the Central Valley are expected to be anywhere from 106 to 112˚F. 



Hideous.

Wednesday, July 25, 2018

Threats from Ensign Peak Fire Continue

Yesterday afternoon, a grass fire quickly burned 100 acres above Victory Lane just north of the Utah State Capitol, threatening homes in the area. 

Source: Rich Bowmer | The Associated Press | The Salt Lake Tribune
Smoke from the fire sent a chill up my spine as it emerged from Capitol Hill, illustrating that this was a very serious situation. 


Kudos to the Salt Lake City Fire Department, which responded quickly and got the situation under control.  According to the Salt Lake Tribune, only one home was damaged.  Three firefighters were, however, hospitalized, two for heat exhaustion and smoke inhalation and one for a leg injury.  We wish them speedy and complete recoveries. 

The origin of the fire remains unknown, but was almost surely human caused.  The threat of a similar fire remains, with caution, vigilance, and taking steps to protect your home the keys to reducing risk.  Below are recommendations of the National Fire Protection Association. 
Some neighbors in the Avenues hired goats to consume grasses on the slopes below their homes a couple of weeks ago, and I thought that was looking like a really good investment yesterday.  

Although the Ensign Peak Fire is contained, the area is denuded of vegetation and will be prone to erosion and potentially debris flows during precipitation events.  Threats from wildfires continue even after the last ember is extinguished. 

Tuesday, July 24, 2018

A Beastly July Ridge Dominating Southwest Weather

Take a gander at the GFS 10-day forecast below, especially the top frame, which illustrates the evolution of the winds on the dynamic tropopause (jet-stream level).  Note the slow westward movement, or retrogression, of a very strong upper-level ridge across the southwest US and northern Mexico during the period. 


The intensity of this ridge over the southwest US and northern Mexico is quite unusual for this time of year.  For example, the NAEFS mean 500-mb height forecast for 1800 UTC today shows values that are outside climatological values for the 1979-2009 period.  In other words, we are dealing with unusually strong ridging at those latitudes for July.

Source: NWS
In general, people associate high pressure with fair weather, but the #1 weather-related killer nationally is heat and a strong ridge this time of year over the southwest makes for extreme heat.   As can be seen in the NWS forecast below, excessive heat warnings extend across much of southern Arizona and California, and up the lower Colorado River Valley to portions of Nevada and southern Utah. 

Source: NWS
I'll provide the NWS infographic below as an example of forecasts for today's max temperatures, which include everything from 123˚F in Thermal to 96˚F in Los Angeles. 

Source: NWS
With the ridge moving so slowly, this is going to be a multiday event.  Riverside, for example, is currently 102˚F (1:15 PM PDT), with a high expected to be near 110˚F today, tomorrow, and Thursday.  Riverside is inland enough that it is typically warmer than Los Angeles, but still, the average high this time of year is about 94˚F, comparable to the average for Salt Lake City.  

Source: NWS
We should all feel fortunate that we're on the periphery of this ridge and only running in the mid 90s here in Salt Lake.