Monday, July 16, 2018

Upper-Level Flow Forecast over the Western U.S.

This morning's 500-mb upper air pattern features an upper-level ridge, or anticyclone, centered off the southern California coast.  The anticyclone is zonally elongated, which means stretched in an east-west direction.  The flow at this level roughly parallels the 500-mb height contours, with lower heights on the left, which yields easterly flow to the south of the anticylcone over Mexico and the subtropical eastern Pacific Ocean, and westerly flow to the north over Canada and the Pacific Northwest. 


Such a pattern is not unusual in July, although in this case, the anticyclone is centered west of its climatological mean position over southern New Mexico and the easterlies to the south are a bit stronger than average. 

There are two important smaller-scale features at this level.  The first is a trough in the westerlies over the Pacific Northwest, indicated by a brown dashed line.  The second is a trough in the easterlies over northern Mexico, also indicated by a brown dashed line.  Meteorologists typically call such features short-wave troughs, although troughs in the easterlies are often called easterly waves

The ability to predict the movement and evolution of both the large-scale cyclones and anticyclones, as well as short-wave features, is critical for weather prediction.  During the monsoon, these features play an important role in moisture transport, convective initiation, and precipitation coverage and intensity. 

The loop below shows the GFS forecast for the next 5 days, ending at 1200 UTC (0600 MDT) Saturday 21 July.  Note how the short-wave features "pinwheel" around the anticyclone.  This is a defining characteristic of upper-level waves.  Short-wave features move faster than long-wave features.  The short-wave trough in the northerlies moves over the upper-midwest and amplifies, forming a stronger upper-level trough over the Great Lakes region.  Similarly, the easterly wave moves over the eastern Pacific and amplifies, closing off west of California.  Meanwhile, the anticyclone shifts slowly eastward, ending the loop centered over New Mexico and west Texas. 


The image below is for the end of the loop [i.e., 1200 UTC (0600 MDT) Saturday 21 July] to highlight those key features.  In addition, the position of the anticyclone and easterly wave opens up the potential for the transport of moisture later this week and weekend.  For example, such a pattern is one where the Sierra Nevada could see some thunderstorm activity. 


All of this is based on one model forecast produced by the Global Forecast System (GFS).  Typically the details of the forecast are sensitive to how all these features interact, and this is why meteorologists consult ensembles and multiple modeling systems to try and get a handle on the full range of possibilities. 

Sunday, July 15, 2018

Even Meteorologists Get Burned by the Weather

After an aborted attempt to ski Kings Peak in May (see Uinta Misadventures), my son and I decided we needed to go back this summer and make the summit.  I have lived in Utah for 23 years and incredibly haven't done Kings Peak, so we left Friday afternoon to try and bag it Saturday (yesterday). 

The hike in on Friday evening was as enjoyable as a long slog can be.  The meadows were pretty and the trail dry and fast.  We realized quickly what a folly it had been to try and ski Kings in May with patchy, unsupportable snow on AT gear.  Good golly, what a long approach for what would have been a minimal amount of turns!


Friday night I awoke at 2 AM or so and peered out at wonderfully clear skies.  Sunrise Saturday morning was beautiful. 


However, just visible in the pond reflection are some clouds that were floating about and gave me a little heartburn.  I was mainly concerned about afternoon thunderstorms.  I had anticipated a slight threat of those happening as often occurs in the Uintas, and this was also reflected in the National Weather Service Forecast for the western Uintas issued Friday afternoon. 


We left our campsite around 7:30 am, and already the partly cloud skies were starting to fill. 


Nearing the summit at 9:30 am, it was clear things were going south with showers in many areas, including looking west. 


A bit later, at the summit, it was clear that the 30% chance would "verify" and that things were falling apart sooner than anticipated, although thankfully we hadn't heard thunder or seen lightning.


As we took a summit photo, it was just starting to sprinkle. 


And, looking west, it was clear that things were going to change.


We began our descent.  When we reached the summit, we were the only ones on top and we hadn't passed anyone descending.  On the descent, the line of climbers was long.  We had fortunately brought some layers and rain gear, but others were in true Alpine style with shorts, thin T-shirts, and minimal gear if any.  A few were in sandals.  Kings Peak is a long ways from home when the weather goes south.  We were glad to have brought up some warmer clothes.

Indeed, the rain came in on the descent, and we had steady develop as we descended below Gunsight Pass. 


Fortunately, we got a break before reaching camp.  My son wanted to head all the way out so he could watch the World Cup Final this morning, so we spread stuff out to dry and I caught I quick nap.  We broke camp and began the long slog out, with rain starting again shortly thereafter. 

Really, it didn't rain all that much, but it was enough that portions of the trail turned into a quagmire.  At this point, we kept our heads down and the legs churning. 


All of this is a reminder that Meteorologists get burned by the weather too and that a 30% chance of showers doesn't mean a 0% chance of showers.  On the other hand, I the early development of showers that morning was a surprise.  I consider this a penalty for not paying proper sacrifice to the Gods of Kings Peak.   Clearly that area is cursed for me.  At least we summited and enjoyed a decent view. 

Friday, July 13, 2018

Large Climate Vulnerability at the Proposed Nordic Valley Ski Resort

Nordic Valley is a small ski area near Eden in the Odgen Valley east of the northern Wasatch Mountains.  It has a base elevation of 5400 feet, the lowest in Utah, and a vertical drop of 1000 feet.

The owners, however, have recently announced major expansion plans (see this Salt Lake Tribune article published this morning and this Ogden Standard-Examiner article published on June 25th) that include the installation multiple lifts including a 4.3 mile long gondola from North Ogden and expansion onto 2800 acres of national forest.  The map below is from the Nordic Valley expansion plan web site (https://nordicvalleyproject.com), which unfortunately is oriented so that north is toward the bottom.  The summit elevation would be around 8100 feet, a tad higher than the base of Snowbird and a tad lower than the base of Alta.

Source: https://nordicvalleyproject.com/
There are a host of concerns about the proposed project highlighted in the articles linked above, but let's talk about this from a weather and climate perspective.  This would be a remarkably low elevation ski area for Utah, with a base on the Eden side near the current 5400 feet and, if the map above is to be believed, 4725 feet on the North Ogden side.

In the climate of the late 20th and early 21st century, the area around Eden has been quite snowy for its elevation.  As I like to say, pound for pound it is the snowiest place in Utah.  Just to the north of Nordic Valley, the Ben Lomond Trail Snotel Site at 5971 feet has a maximum median snowpack water equivalent of 19.1 inches in late March.  Observing sites don't exist elsewhere in the Wasatch at that elevation, but I suspect there's nowhere in the range at around 6000 feet that compares to that.  Higher, at the Ben Lomond Peak site at 7688 feet, the maximum median snowpack water equivalent is 37.2 inches in early April.  This is higher than the 24.1 inches at Thaynes Canyon (9247 feet at Park City Mountain Resort) and just a bit lower than the 42.9 inches at Snowbird (9615 feet).  

However, the low elevation makes Nordic Valley the most vulnerable ski area in Utah to climate change.  The graph below illustrates estimates of the fraction of precipitation that currently falls as snow that would instead fall as rain at Wasatch and Oquirrh Mountain SNOTEL sites for every degree Celsius of warming.  By far, the highest sensitivity is the Ben Lomond Trail site, with a 20% reduction for 1˚C of warming, 40% for 2˚C, 55% for 3˚C, and 70% for 4˚C.  Ben Lomond Peak's sensitivity is lower due to it's higher elevation, but it is still larger than at Thaynes Canyon or the Snowbird SNOTEL due to it's lower elevation.  Snowpack sensitivity, not examined here, would probably be higher.  
Source: Jones (2010)

The bottom line is that the new Nordic Valley, even with expansion to the Wasatch Crest at 8100 feet, will still be the must vulnerable Wasatch Mountain ski resort to future climate change.  It is at an elevation where the fraction of wintertime precipitation that falls as snow will be decreasing the fastest and at which vulnerability to wintertime thaws and sublimation losses will be the highest.  

On the other hand, the owners don't seem to be too concerned.  In an interview with the Ogden Standard Examiner, James Colman, the resort manager said,
"There’s been climate change for millennia. There’s no question the Earth goes through cycles, there is climate change, in general the Earth has been heating up. It’s not something I worry about a whole lot myself. We do the best we can to deal with it, to improve our snowmaking, to improve the way we manage the mountain.  
"I just think there are bigger things I have to deal with, personally, that I can have more control over than the climate. I don’t think it’s conclusive, personally, that climate change is human caused. My home in Durango, 10,000 years ago, was under 2,000 feet of ice."
SMH.

Thursday, July 12, 2018

Thinking of Kikkan Randall and Others Affected by Breast Cancer

Olympic gold medalist Kikkan Randall announced yesterday that she was recently diagnosed with breast cancer. 

Randall is a 5-time Olympian and 13-time World Cup race winner in cross country skiing.  She and Jessie Diggins provided one of the great moments during the 2018 Pyeongchang Winter Olympics when they won the women's team sprint and earned the first Olympic gold medals for a U.S. cross-country skiers. 

Jessie Diggins and Kikkan Randall (right).  Photo: Sarah Brunson/U.S. Ski & Snowboard.
Randall's diagnosis hits home for me as my wife is a two-time breast cancer survivor.  According to the Anchorage Daily News, Randall found two pea-sized lumps in her breast on Mother's Day and will begin chemotherapy this week.  Like many younger women affected by the disease, she is a mother, with a 2-year-old son. 

There is a 1 in 8 chance of a woman in the United States developing breast cancer during her life time.  However, there are also 3.1 million breast cancer survivors in the United States and many reasons to be optimistic.  Increasing survival rates in recent years are believed to be due to catching breast cancer earlier and improved treatments.  Forty percent of breast cancers are discovered by women who find a lump, as was the case for Kikkan, highlighting the importance of performing self exams and taking action to see a doctor if anything unusual is detected. 

I am thinking of Kikkan and everyone who is affected by breast cancer today.  Be vigilant, perform self exams and screenings as recommended by medical professionals, and keep the faith. 

Wednesday, July 11, 2018

Salt Lake's July "Human Misery Index" Is Climbing

Human comfort is strongly influenced by a number of factors including temperature, humidity, cloud cover, and wind.  For the purposes of this post, I am going to focus on one that I consider to be especially relevant to human comfort in the Salt Lake Valley, the minimum temperature.

In particular, I am going to declare 70ºF as a critical threshold in comfort, with minimum temperatures below that value generally yielding reasonable comfort, whereas minimum temperatures above that level generally yielding uncomfortable sleeping conditions.  Going a step further, I'll define the human misery index in Salt Lake City as being equal to the number of days with a minimum temperature at or above 70ºF. 

Looking at historical data for the Salt Lake City Area stretching back to 1874, we see a rapid change in the July human misery index beginning around Y2K.  In particular, around that time a clear upward trend began and we have had five Julys since 2007 with 15 or more days with a minimum at or above 70ºF, something that never happened previously. 

Source: NOAA Regional Climate Centers
So, if you think that nighttime comfort around here ain't what it used to be, you are right.

This trends has a variety of implications for everything from human and environmental health to electricity demand. Cooling degree days in July, for example, show a gradual increase for the periods prior to 2000, but since then, we've been experiencing a new normal, with the average number of days clearly higher and several years with values near or above 600.  

Source: NOAA Regional Climate Centers
Thus, in addition to growth and increased use of air conditioners, a hotter valley climate is also contributing to increased electricity usage.  

Development and associated urban heat island effects, global warming, and recent circulation patterns are possible contributors to these recent trends, although I am unaware of a study that has attempted to quantify the contributions of each of these effects.  I suspect it is likely that that both the urban heat island and global warming are contributing significantly to the upward trends.  It is possible that instrumentation moves and local conditions around the airport might also be contributing.  

Personally, I'm starting to find all of this quite depressing.  Mother Nature might perturb the jet stream some summer to give us an unusually cool July, but it is difficult to imagine the long-term trend not being towards an even hotter future.  By the end of the century, Salt Lake could be the new St. George.  Good luck with that.   

Note on Comments:

I usually try to keep up with comments, but for some reason, blogger is no longer sending me an e-mail when you comment.  As a result, I've been missing your comments.  Please keep commenting.  I'm hoping to get this fixed and to be better about responding.  

Sunday, July 8, 2018

Observations from Mt. Baldy and Hidden Peak

Beating the heat, I did a quick climb of Mt. Baldy and Hidden Peak this morning, giving my knees a break with a descent via the Snowbird Tram.  Some observations.

I was on the summit of Mt. Baldy at about 9:45 am.  The view to the east was a scene from the Great Smokies and a good example of how smoke can become trapped in valley cold pools that develop overnight. 


We've been fortunate in the Salt Lake Valley to have not been in the smoke plume except for a brief period late Thursday night and Friday. 

For snow lovers, I found the patch below at about 9400 feet in an area where contributions of artificial snow to the snowpack would probably be small to non-existent. 


I'm guessing it is the lowest remaining snow in the Wasatch.  Prove me wrong...

Finally, a little comparison of the snowpack on this date (8 July), compared photos I've taken in July the previous two years.  The situation this yea is pretty grim.  Just a few patches to be had on the north side of Twin Peaks and in the usual spots in Upper Hogum. 


Last summer was preceded by a much better snow season and it shows.  The photo below was taken 22 July 2017 when you could almost send it down the Pipeline couloir and coverage in upper Hogum was more extensive. 


If we go back a bit further, to 26 July 2015, one find a situation in which there was virtually no snow except in a few very small pockets. 


Will we get to nearly snow free by the end of the month and will we have a snow-free Wasatch before the start of the next snow accumulation season?  Time will tell.