Friday, January 18, 2019

The Steenburgh Effect Giveth

What can I say.  The Steenburgh effect just keeps on giving.

Since leaving Utah a couple of days ago, the Wasatch Range has gotten pounded.  I'm not paying close attention to the weather there, but I have gotten messages thanking me for leaving and did notice that Alta's web site is reporting 21 inches in the past 48 hours. 

Meanwhile, the northern Alps were coming unglued prior to our arrival.  Too much of a good thing.  The Steenburgh effect giveth here as well as a break was sorely needed to allow for transportation routes to reopen and the avy danger to subside.  Since we've arrived, it's been partly to mostly sunny skies in Innsbruck with just a few spits of snow (although there were a few inches at some mountain locations last night).  I think the locals are thanking me for now, but they might run me out of town if this continues for a few more days. 

Meanwhile, I "moved" into my temporary home at the University of Innsbruck.  This might be the most spectacular setting for a mountain meteorology program in the world.  Below is the view looking eastward down the Inn Valley from my office. 


Although we are chomping at the bit, Andrea and I have not been able to ski yet.  More on why perhaps in a future post. 

Thursday, January 17, 2019

The Stoke Is High

Andrea and I arrived in Innsbruck yesterday for the start of my Fulbright Professorship at the University of Innsbruck.  The stoke was high as we flew into Munich and then shuttled to Innsbruck, which allowed us to start in the plains and proceed into the Alps in spectacular fashion.  Thanks to recent storms, the mountains were pasted white and we had about as much fun as you can have crammed into a shuttle bus.

Approaching Innsbruck from the east
We were very pleased to find the apartment we rented site unseen exceeds expectations.  It was recommended by a previous Fulbright professor, but I think he undersold it.  It is surprisingly spacious and has a nice Tirolian flair, especially in the bedroom where there are beautiful wooden built-in cabinets and beams.  We also have some nice vistas from the windows and balcony. 

Looking south at the Patscherkofel ski area, where Franz Klammer famously won the Olympic downhill gold medal in 1976.  North facing, I've watched it as we've run errands today and it's been continuously in the shade all day.  It must be a cold place to ski!  Also evident at right is the Bergisel ski jump, which is a beautiful structure built right in town.  
Looking north toward the Nordkette and Karwendel Alps


Tired and jet lagged, we enjoyed an evening walk into the old town for dinner.  Sadly the photo below doesn't do the evening light justice.      

Nordkette and the Karwendel Alps
We've been running errands and doing a little work today.  We had planned to ski tomorrow (Friday), but Delta sent our ski bags to Amsterdam instead of Munich.  No word yet on when we will receive them.   

Rumors are that the stoke is high in Utah as well with another storm underway.  Enjoy the powder.

Monday, January 14, 2019

Contrasts between Persistent and Diurnal Cold Pools

Great examples of persistent and diurnal cold pools exist presently over northern Utah.

The persistent cold pool exists over the Great Salt Lake Basin, including the Salt Lake Valley, where widespread fog and stratus are present, as illustrated by yesterday afternoons modis imagery.  It is sometimes difficult to discern fog and stratus from snow in visible imagery, but the smooth nature of the coverage and the inability to see the Great Salt Lake are dead giveaways. 

Modis Imagery 13 January 2019
One can also use multiple satellite channels to detect fog and stratus, as is done in the image below for 0915 UTC (0215 MST) this morning.  Note the area of white covering the Great Salt Lake Basin, as well as the Uinta Basin to the east. 

Source: NWS Aviation Weather Center
The sounding from the Salt Lake City International Airport shows a relatively deep cold pool extending from the surface to 814 mb (6250 ft).  The temperature then increases 6ºC in a sharp inversion layer (indicated by orange).  Above that level, the atmosphere is quite dry throughout the remainder of the troposphere (green). 

Sounding source: SPC
The low clouds over the Salt Lake Valley sit right at and below the base of the inversion, resulting in a sea of stratus covering the Salt Lake Valley, as can be seen from the Snowbird Prism Cam.

Source: Snowbird
Below the stratus, a dreary, dark scene exists, with cloud base somewhat poorly defined.  The photo below was taken looking south from the upper Avenues. 


As we have discussed previously, although it looks dark and dreary, the reality is that a deep cold pool of this type, capped by stratus, results in mixing through a deeper layer than when the inversion is based right at the valley floor.  As a result, while there is still pollution, the concentration levels along the valley floor are not as bad as in periods when the inversion is lower.  Note, for example, how PM2.5 concentrations over the past couple of days have been lower than they were on the 10th and the 11th. 

Source: Utah Division of Air Quality
In contrast, a diurnal cold pool exists this morning in the Snyderville Basin near Park City.  There, with clear skies overnight, temperatures plummeted and at 15:16 UTC (0816 MST) were -8ºF at Silver Junction and Kimball Junction.  It was also 2ºF at the Park City Golf Course.   In contrast, it was in the mid 20s mid mountain at Park City Mountain Resort. 


Although the persistent cold pool present over the Salt Lake Valley doesn't burn off during the day, the cold pool in the Snyderville Basin is diurnal.  It forms at night and burns off during the day. 

Compare, for example, the temperature traces (red line) at the Salt Lake City airport and Silver Creek Junction (note scale change).  There is practically no diurnal (daily) temperature cycle at the Salt Lake City International airport.  Instead, there is a gradual decline in temperature during the period.  This reflects the presence of low clouds, which reduce incoming solar radiation received at the ground as well as the overnight cooling.  We remain capped by an elevated inversion all day long. 


In contrast, there is a huge diurnal cycle at Silver Creek.  Temperatures last night and the previous night fell to below zero, but yesterday afternoon, the high was 30ºF.  Here, a shallow cold pool forms under clear skies each night, and then burns off during the day. 

Residents of the Summit Park area observe some remarkable temperature variations on days like this.  Note how it is -8ºF at Kimball Junction, -6ºF along Pinebrook Boulevard near I-80, 9˚F near the top of Pinebrook Road, and 21˚F across I-80 at the Parley's Summit SNOTEL.


My skate ski today, which will be my final ski of the season in Utah, will need to wait until afternoon when temperatures are more tolerable...

Sunday, January 13, 2019

Dumpage in the Northern Alps

It has been a remarkable start to 2019 in the northern Alps where snowfall has been frequent and heavy, including in low elevation areas in the Alpine foreland (i.e., foothills).  We'll focus here on the Loser-Altaussee ski area southeast of Salzburg and indicated by the red thumbnail below. 

Source: Google Maps
The lift-served terrain in the area extends from 850 to 1800 meters (2800 to 5900 feet).

Source: https://www.loser.at/
Snow depths being reported for the resort on bergfex.com this morning are 250 cm (100 inches) in the valley and 490 cm (nearly 200 inches) on the upper elevation.  I'm not sure how good those numbers are, so it is worth an eye test.  Here's a shot from the camera at the top of the resort as the sun set this afternoon.  Deep. 


The ski area is shut down due to high avalanche hazard.  Serious avalanche hazard. 

Source: https://www.loser.at
From a meteorological perspective, the driver of all this snow has been a persistent high amplitude flow pattern featuring ridging over the northeast Atlantic and troughing over eastern Europe.  This had led to the passage of troughs in northerly to northwesterly flow, with precipitation enhancement over the northern Alps.  Note that some of those troughs also produced heavy snowfall in southeastern Europe and central Italy, the latter due at least in part to sea effect generated over the Adriatic.  


Heavy snowfall continues in the northern Alps today.  The Météo France Arpege model forecast valid 0000 UTC (0100 Central European Time) Monday shows moist northwesterly flow impinging on the Alps with rainfall in the upstream lowlands and heavy snowfall in the northern Alps.  

Source: wxcharts.eu
I don't know how good the Arpege new-snow depth totals are, but significant totals (> 50 cm/20 inches) are predicted from France to eastern Austria with a maximum (128 cm/50 inches) in the Arlberg region of Austria.  

Source: wxcharts.eu
Equally remarkable to the snow totals in the northern Alps is how little snow there is in portions of the southern Alps, such as the Dolomites.  The image below was taken this afternoon above the Val di Fiemme southwest of Balzano, Italy.  

Source: https://www.dolomitisuperski.com
Will the Steenburgh effect put an end to this insanity?  We will find out soon enough as we arrive in Innsbruck on Wednesday.  

Saturday, January 12, 2019

An Elevated Inversion

It is worth a look at the intricacies of our current inversion event in which the inversion has lifted some, which brings with it some good news for valley residents and some bad news for bench residents. 

Note how in the morning sounding below, temperatures decrease from about 0ºC at the surface to -5.3˚C at 6400 ft (810 mb) where the inversion is based. 

Source: SPC
As a result, instead of pollutants being trapped in a very shallow layer close to the valley floor, they are actually mixing through a depth of about 2000 feet.  This means lower pollution concentrations on the valley floor.  Note, for example, how much lower PM2.5 concentrations are today compared to the previous day at Hawthorne Elementary (it's possible there was some flushing in of cleaner air in easterly flow too, but I suspect the raising of the inversion was also a contributor)

Source: DAQ
On the other hand, the deeper pollution layer means higher pollutant levels on the upper benches (compared to shallower events) and in some areas such as the lower canyons.  The photo below, taken looking north from upper Mill Creek Canyon, shows low clouds tonguing up Parleys Canyon, and with it air pollution.  Skate skiers at Mountain Dell, for example, are probably seeing moderate air quality levels this afternoon.  That might also be true in lower Mill Creek Canyon.  


The Snowbird Prism Cam also shows the sea of stratus over the Salt Lake Valley, with a tongue pushing up Little Cottonwood.  


I suspect the development of down valley flow tonight will cause a flushing of clean air into the lower canyons, which will be followed by a push of dirty air and stratus up the lower canyons tomorrow, as occurred today. 

Friday, January 11, 2019

Sixth Anniversary of the Avenues Whiteroom

This is a repost from 11 January 2013 just because it is fun to reminisce.

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The U closed today at 1 PM and we took full advantage by taking a tour in the Avenues Foothills.  There's an impressive snowpack at the top of Terrace Hills Drive (~5000 ft).


Good cover on the mountain bike trails.


We made a brief visit to the white room.  Yes folks, this was in the Avenues foothills.



The snowpack on the north aspect is quite scary.  Facets down low (very soft) and column failures with isolation at the old snow/new snow interface.  We kept slope angles low, which made it a bit challenging to keep momentum going given the depth of the new snow.  Better safe than sorry.  

 

In all honesty, the snow is too deep and too dry for good skiing.  I think the skiing will be better once things settle out some.  When's the last time you said that about skiing from town?