Come See the Doppler on Wheels this Saturday!

Lessons in Boundary Layer Meteorology

The boundary layer is the lower portion of the atmosphere that is affected by friction and the transfer of heat from the earth's surface into the atmosphere.  It's depth varies depending on the time of day, the environmental conditions, and the local land surface and topographic characteristics.

Typically the evolution of the boundary layer is conceptualized as shown below.  During the morning, sunlight heats the Earth's surface, resulting in a transfer of heat into the atmosphere.  This erodes the shallow stable layer that typically forms overnight from radiational cooling.  The boundary layer then continues to grow, eventually reaching maximum depth later in the day (the time varies depending on conditions).  Within the boundary layer, turbulence driven by wind shear and surface heating results in considerable mixing.  Concentrations of gasses like water vapor and carbon dioxide are often nearly constant with height in the boundary layer.  Hence, the "mixed layer" label in the schematic.  Often there is a stable layer or inversion at the top of the mixed layer. 

Source: COMET/METED

Near and after sunset, the Earth's surface cools rapidly.  Heat is transferred from the atmosphere, which cools rapidly near the Earth's surface.  This forms a shallow nocturnal stable boundary layer, that may be tens or perhaps one or two hundred meters deep.  Above this layer, the old remnants of the boundary layer remain.  This layer is called the residual layer.

In quiescent weather conditions, this pattern repeats itself daily: 1. The sun rises;  2. The nocturnal stable boundary layer is "burned off";  3. The boundary layer grows rapidly into the residual layer and constituents (including pollutants) are mixed through its depth;  4. The sun sets and the nocturnal boundary layer forms and strengthens, leaving a residual layer aloft.

Evidence of these processes was very apparent on my ride above Ensign Peak this morning.  At the time, the top of the pollution layer was perhaps 1 km above the valley floor.  There was a very clear discontinuity in the pollution at that level.  It was early enough that I suspect that discontinuity did not mark the top of today's boundary layer, but instead the top of the residual layer, which was loaded with pollutants from emissions from yesterday.

I've added by eye yesterday's sounding (red=temperature, green=dewpoint) from the airport.  In this case, the temperature or dewpoint decrease if the line slopes to the left and increase if it slopes to the right.  The top of the residual layer was very near the elevation of an inversion in yesterday's sounding, as one might expect.  Below that inversion, the atmosphere yesterday afternoon was relatively well mixed.  For example, temperature decreased rapidly with height at a rate of about 10ºC per kilometer, which is consistent the density being constant with height.  Dewpoint decreased with height at a rate close to that expected if the concentration of water vapor is constant with height.  However, the decrease with height near the surface was more rapid than one might expect if the atmosphere is well mixed.  This isn't unusual as the turbulence typically can't mix the atmosphere fast enough right near the ground to make the water vapor concentration constant with height if there is evaporation or transpiration occurring.

Expect views like this most days this week due to the presence of high pressure.  Note that the sharp top of the residual layer is most apparent in the morning and evening if you are at an elevation somewhat above the valley floor and you face somewhat toward the sun (but perhaps not right at it).  This is an optical effect related to how pollution scatters sunlight.

Announcement

I'm pleased to announce that we will be exhibiting the Doppler on Wheels mobile radar (pictured below) at the Natural History Museum of Utah this coming Saturday, November 4, from 10–5 PM.  Bring yourself, the family, and friends.  The exhibit is also one of their Behind the Scenes days when they open the place up for a public viewing of their collections.  Come and geek out!

Important Reading for Faculty and Students

Source: Nature

A short article appeared in Nature this week entitled Graduate survey: A love–hurt relationship.  I'm not a fan of the title, but the article is important reading for prospective graduate students, current graduate students, and university faculty. 

The article summarizes the findings of a survey of 5700 doctoral students worldwide.  Perhaps not surprisingly, the responses "uncovered a strong, perhaps crucial, connection between a well-matched PhD adviser and the student's success."  In my experience, it is often the adviser–student relationship that determines student success, rather than the graduate program.  If you are a student, chose your adviser carefully.  Make your choice of adviser a higher priority than your choice of program if you are in a fortunate position to have such a choice before entering graduate school.  If you are an adviser, recognize that student success equates to your success.  One size doesn't fit all.  Recognize that students have varied abilities and goals and adapt your mentoring accordingly. 

One of the more important topics covered was student anxiety and success.  I was surprised to read that anxiety and depression are prevalent in graduate student life.  More than a quarter of the respondents listed mental health as an area of concern and 45% had sought help for anxiety or depression caused by their doctoral studies.  Of these students, only 35% felt they had helpful resources at their institution and 20% said they didn't feel supported. 

I am now more than 20 years out of graduate school.  I remember anxious times in graduate school, but I've largely forgotten those issues and tend to remember the good times.  Thus, seeing those numbers was eye opening for me and an important reminder of the challenges facing our graduate students. 

There are may other nuggets in the article that should be helpful for students and faculty.  It's well worth the quick read. 

National Park Entrance Fees

Nobody goes there anymore, it's too crowded.

–Anonymous

Some things are a shame, others are a damn shame.  The overcrowding, overuse, and underfunded nature of our natural parks fall squarely in the latter category.

Delicate Arch, an icon of the Utah landscape.  Arches National Park.

According to an article published this week in the Salt Lake Tribune, the maintenance backlog in America's National Parks now totals $11.3 billion, including $278 million for Utah's parks.  

To address this backlog, as well as to "improve facilities, infrastructure, and visitor services, the National Park Service is now proposing to raise entrance fees seasonally in 17 national parks to $70 per vehicle, including Arches, Bryce Canyon, Canyonlands and Zion.  Public comment regarding this proposal is now being accepted at http://parkplanning.nps.gov/commercialtourrequirements. 

Chronic underfunding of the National Park Service and controversy over visitor fees appears to be nearly as old as the National Parks themselves, the first of which was established by the Yellowstone National Park Protection Act signed by Ulysses S. Grant on March 1, 1872.  In fact, an entire book has been written on the subject, Visitor Fees in the National Park System: A Legislative and Administrative History, by Barry Mackintosh. 

In an ideal world, these National Parks would be adequately funded by Congress.  Park visits would be attainable for all Americans.  A $70 entry fee is unaffordable for some families.  Yes, an annual pass would still be only $80, but not everyone visits multiple parks on multiple days.  For some, a one day visit to a national park is the trip of a lifetime, and a $70 entrance fee is an impediment to such an experience.

Meanwhile,  many parks are under great pressure from visitation.  In 2012, Zion National Park set an all-time record with 2,973,607 visitors.  By 2016, they hit 4,295,127 visitors.  Overcrowding and overuse are further stressing the parks and degrading the park experience.  

I don't have any solutions for these problems.  I haven't sat on my bar stool long enough.  I wish Congress better funded the National Park System.   I could live live with a reservation system for entering some National Park areas.  I hope, however, that park fees are not levied in a way that visits become unaffordable for some American families.  I'm disgusted that such a proposal is being floated.  

Birdbrained Meteorology

A recent study published in the International Journal of Biometeorology by Augusta Williams and Neil Laird (unfortunately paywalled, including from campus) uses data from the National Weather Service Radar on Promontory Point (KMTX) to examine the migration of eared grebes near the Great Salt Lake.

Source: audubon.org

The backstory behind the paper is an interesting one.  Neil Laird is a professor at Hobart and William Smith College in western New York who studies lake-effect snowstorms.  He and a group of students were examining radar imagery from the Great Salt Lake when they started seeing some unusual patterns that were clearly non-meteorological and desired an explanation.  As illustrated by one event presented in the paper, these patterns feature an elongated reflectivity maximum that develops near the south shore of the Great Salt Lake and grows southward, covering the Tooele Valley and Rush Valley.  At times, there is a weaker but similar feature in the Skull Valley.  

Source: Williams and Laird (2017).

It turns out the odd pattern is produced by the migration of eared grebes, a waterfowl species that find a home on the Great Salt Lake during fall and early winter to feed on brine shrimp.  Estimates suggest there are 1 to 1.5 million of these grebes on the lake during this period.  

Augusta and Neil went through 15 winters of radar data, ultimately showing that there are an average of 19 radar-detected eared-grebe migrations each winter, although there is quite a bit of variability from year to year.  Migrations typically occur under clear skies and high pressure and become detectable by the radar 30–90 minutes after sunset.  Once leaving the Great Salt Lake, the grebes go to wintering habits in Mexico and southern California.  They show an example of one event where the grebes are detectable in multiple radars from northern Utah to Yuma, Arizona.

Source: Williams and Laird (2017)

My interest in the paper was especially high because we will have a Doppler on Wheels (DOW) radar here in November as part of the Outreach and Radar Education in Orography (OREO) field campaign.

The newly unveiled OREO logo

Thus, I'm looking for uses of the radar during periods of benign weather.  Birds are effective scatterers of radar signals.  For meteorologists, they are a contaminant, but ornithologists can use radars to study bird behavior.  I know nothing about the latter, but during periods of benign weather, bird "hunting" with the radar might be fun.  We could look for eared grebes, or maybe other waterfowl species.  If it flies in flocks, we will probably be able to see it.  An advantage of the DOW is that we will be able to scan just above lake level (the lowest tilt of the National Weather Service radar is 3000–5000 feet above the lake and nearby valley floors), perhaps enabling the initial detection of the migration.  Our ability to configure the DOW scanning pattern may also allow us to better target and track some of the flocks.  

I'll call this birdbrained meteorology.  Good work if you can get it.  

Typhoon Lan Has It In for Utah Skiers

Typhoon Lan has been rampaging in the western Pacific, reaching a maximum intensity of category 4 on the Saffir-Simpson scale.  It made landfall early Monday morning (local time) in Japan, southwest of Tokyo.  Some spectacular photos of LAN were taken from the International Space Station.

#TyphoonLan headed towards #Japan as seen from our Cupola windows. Stay Safe! #VITAmission pic.twitter.com/hk0Mpln2Ji

— Paolo Nespoli (@astro_paolo) October 21, 2017

Although half a world away, Lan will have some dramatic influences on the upper-level flow and unfortunately has it in for Utah skiers.

The image below shows the situation at 1200 UTC 21 October (0600 MDT Saturday) when LAN was still south of Japan.  Sea level pressure contours are colored (cooler colors indicate lower pressure) and 500 mb (upper-level) height contours black.  At this time, the upper-level flow over the mid-latitude north Pacific was primarily zonal, meaning from west to east, with a broad trough over the high-latitude North Pacific and Bering Sea. 

Lan struck its first blow for Utah skiers as it moved northward and across Japan.  During this period, the northward transport of tropical warmth and moisture, combined with condensational warming near and ahead of the system, built a ridge over the western pacific and perturbed the midlatitude flow, which quickly broke down across the entire Pacific basin.  At 0000 UTC 23 October (1800 MDT Sunday), a broad ridge was amplifying upstream of Utah, deflecting Pacific moisture to our north with just a few high clouds spilling across our area. 

Blow two comes as Lan undergoes extratropical transition and explosively develops as a midlaitude cyclone off the Kamchatka Peninsula.  This encourages further amplification of the large scale flow, which by 0600 UTC 24 October (0000 MDT Tuesday) features a high-amplitude trough along the entire US west coast. 

Thus, the beautiful fall weather we will experience in Utah this week comes from Russia with love.  Beware in California, however, as Diablo and Santa Ana winds are possible.

But, Lan isn't finished yet.  Although she weakens weakens, she continues to drift eastward across the Aleutians where the southward flow ahead of her can link up with that associated with a closed low further south and north of Hawaii. 

This ultimately leads to a new tap of tropical warmth and moisture that connects well into the tropics and reinforces the west coast ridge. 

Here's the whole thing in motion.

So, what does this all mean?  Well, it means we won't be seeing any significant snow around here through the end of October.  It means the start of ski season is officially on hold until November.  And it means you should get that bike tune up you've been putting off because you will be spinning instead of skinning. 

Is this unusual?  Nope.  Disruptions of the midlatitude flow by tropical cyclones are common in the fall. 

Lessons from Orographic "Cumulus Patheticus"

After yesterday's dustpocalypse, the weather this morning seems relatively benign, but there's always something to be learned. 

Overnight and early this morning, orographically (i.e., mountain) forced cumulus clouds developed over the Wasatch Range. 

The unofficial name for such shallow cumulus clouds is "cumulus patheticus" as they are pretty wimpy compared to their cumulonimbus (towering clouds associated with rain and thunderstorms) brethren. 

Officially, they are stratocumulus clouds.  In this instance, lifting by the mountains appears to have been essential for their formation.  The GOES 16 satellite image for 1512 UTC (0912 MDT) showed the clouds were confined primarily to very near and downstream of the Wasatch Range, with lee waves generating wave-like clouds further downstream. 

This morning's satellite imagery shows that the clouds were confined to a layer between about 750 mb (about 8000 feet) and 550 mb (about 16,000 feet).  A pronounced stable layer with a base at 550 mb (16,000 feet) prevented penetration to greater heights. 

Source: SPC

The cumulus patheticus did produce some small snow pellets in the Avenues overnight.  I suspect there were a few snow showers in the central Wasatch as well.  

Shallow cumulus clouds like these can produce prolific mountain snowfalls under the right circumstances.  This morning, we appeared to be moisture limited given the large difference between the temperature and the dewpoint at low levels.  This, combined with the stable layer aloft, limited cloud depth and updraft strength.  More moisture at low levels would have likely enabled deeper clouds, stronger updrafts, and more rapid growth of ice crystals.   

Under such a scenario, snowfall rates of two ore three inches an hour are possible if the cloud exists at temperatures favoring the growth of dendrites, those wonderful 6-armed snowflakes that we all love.  

Orographic clouds do not necessarily need to be deep to be prolific snowfall producers, but they do need the right ingredients. 

Think of this the next time you're skiing, it's snowing hard, and yet you can make out the sun when you look up.  

Postfrontal Dustpocalypse!

A strong cold front raced across northwest Utah this morning, reaching Salt Lake City around noon bringing a blast of moderately strong pre- and post-frontal winds, the latter accompanied by blowing dust.

Dustpocalypse Now!

Observations collected every minute from the William Browning Building (WBB) on the University of Utah campus show a wind shift from SW to WNW from 1153 to 1155 MDT.  Winds continue to turn through NW at 1200 MDT.  From 1153 to 1200 MDT, temperatures fell 10.3ºF.  Pre-frontal wind gusts reached as high as 42 mph a couple hours ahead of the front and peaked at 49 mph at 1209 MDT, just behind the front.

Adding to the story was the post-frontal blowing dust.  At Wendover in far western Utah, the post-frontal visibility dropped to as low as 4 miles, likely due to blowing dust.  However, at the Salt Lake City International Airport, minimum visibilities reached 1 mile, suggesting that dust emissions from the area surrounding the Great Salt Lake and the west desert contributed.

The dust made the cold front very apparent as it entered the Salt Lake Valley (h/t to @UteWeather for tweeting the image below, taken facing from the U toward downtown Salt Lake City).  One can see the classic frontal "nose" to the left of the photo, with friction resulting in a slight forward tilt of the front with height in the lowest one or two hundred meters, above which the front slopes back over the cold air.

The post-frontal air was nasty.  PM2.5 concentrations spiked to 120 ug/m3 on campus immediately following frontal passage.

I guess if you're not going to have much snow, weather excitement like this is better than nothing.

Addendum @1235 MDT:

Shortly after writing this post, the PM2.5 at our mountain met lab topped out over 200 ug/m3 (note scale change from graph above). 

There's some uncertainty in these measurements, so perhaps we should be cautious about the absolute values.  That being said, the air was pretty nasty out there and remains so as I write this at 1235 MDT.

Another Waste of a Trough

Ordinarily, a satellite image like this mornings (below) would get me excited.  There's a cold front over the Pacific Northwest, a deep upper-level trough over the eastern Pacific, and plenty of convection over the eastern Pacific, indicative of cold air. 

Unfortunately, the system has three things going against it.  One is it's moving into the ridge that is parked over the North American interior.  Two is that it's a fast moving system.  And third, there isn't much of a snowpack currently in the Wasatch, so a refresher doesn't do us much good. 

The loop below from the GFS summarizes the first two issues quite well.  Note the weakening of the trough as it moves into the western US and the associated precipitation falls apart and moves quickly across northern Utah. 

Our downscaled SREF forecasts for Alta show most members generating under 0.3" of water tomorrow (Friday) and tomorrow night.  0.7" is the upper end.  Most of this precipitation will fall as snow above 8000 feet, but that's still only an inch or two for about half the SREF members, with perhaps up to 6 or 7 inches for the wettest.  I suspect the wet members bring the trough in a little stronger and a bit further south. 

So, this will be another waste of a trough for the Wasatch, not providing enough for turns. 

If you need to feed the habit with a tour, the Grand Targhee SNOTEL appears to have the highest snowpack water equivalent of any SNOTEL site in the contiguous US with 5.4".  The base of the resort looks thin, but the summit web cam looks inviting.  They also look to do much better than us out of this storm.

Last Half of October Looking "Ridgy"

The period from mid September to mid October was relatively cool in northern Utah, ranking as the 12th coldest on record at the Salt Lake City International Airport and the coldest since 1986. 

Source: NOAA Regional Climate Centers

The period also brought a bit of snow to the mountains, which continues to linger on shady upper-elevation slopes.

However, the pattern is shifting for the latter half of October.  Although we have a cold front moving through the area on Friday, bringing a temporary cool down for the first half of the weekend, the extended range forecasts are strongly hinting that the next 10 days or more will be dominated by ridging over our area.  Below are GEFS forecasts valid 6 AM Monday and Wednesday mornings, showing the jet either to our north on Monday, raking the area along the US-Canadian Border, and high amplitude ridging over our area on Wednesday.  

Source: Penn State e-wall 

Source: Penn State e-wall 

A strong tendency for ridging is also suggested by most members of the GEFS for late next week. 

Source: Penn State e-wall 

By and large, this is not a recipe for October skiing.  We might get a little snow with the front on Friday, and it's possible that something could "slip through the net" over the next 10 days, but by and large, these are pretty pessimistic forecasts for those looking for October turns.

On the other hand, that's not necessarily a bad thing.  Early snow often turns into weak snow (as is happening on the shady aspects where snow lingers) and if we have our druthers, a season that comes on strong in early November is preferred to one that comes in with a bit here and there in October.  The key is for this pattern to change in November, preferably early.  Let's hope that happens.  

Perplexing Probabilities

There are a host of challenges posed in the forecast communications business.  One that I thought of this morning as I surveyed the ensemble forecasts is the low probability, high impact weather event.

Fair weather looks to predominate over northern through Thursday, but on Friday, an upper-level trough moves across the northwest U.S. with the trailing cold front racing across Utah.  The NAM calls for precipitation accompanying the front to be relatively light.  Perhaps some valley rain showers and mountain snow showers, but nothing for skiers to get excited about.  

If we look at our downscaled forecasts for Alta based on the Short Range Ensemble Forecast System (SREF) we find that most members are producing very light accumulations of 0.25" of water equivalent or less through 6 PM Friday (0000 UTC 21 October).  Again, nothing to get excited about.  However, 2 of the 26 members are going bigger and putting out about 0.7" of water or so.  

If we look at our downscaled NAEFS forecasts for Alta, most members producing light accumulations, a few in the 0.4" to 0.7" range, but then two outliers that go absolutely huge, generating about 2.5 inches of water and around 25 inches of snow.  Skiing anyone?

Such outliers are unusual, but not unheard.  However, I don't know of any studies that have attempted to look specifically at the reliability of such low probability, high impact forecasts.  The NAEFS forecast above, if taken literally, would yield about a 10% chance of 20" of snow or more on Friday, but a 90% chance of 7 inches or less.  Is that a reasonable forecast of the probabilities?  In addition, if that was a reasonable forecast of the possible outcomes, how best to communicate that to the public and forecast customers?  "Well, we think that there will be some snow showers.  Odds are it won't add up to much, but there's a slight chance of 20."  That should go over well.

I don't have answers for these questions.  We need better validation studies of our ensembles and, as ensembles improve, better ways to both extract and communicate probabilistic forecast information in a way that is useful to the end user.  

Impacts of Post-Tropical Ophelia on Ireland

Following up on yesterday's post, here's a few tweets from Ireland showing the impacts of Ophelia.

Latest satellite image.
Recent gust of 139km/h at Roches Point Co. Cork#Ophelia pic.twitter.com/xwzxiWn2se

— Met Éireann (@MetEireann) October 16, 2017

Latest wind analysis.
Hurricane Force winds on the SW coast.
Recent gust of 156km/h at Roches Point.#Ophelia pic.twitter.com/5wKdvUNjJa

— Met Éireann (@MetEireann) October 16, 2017

The eye of the storm passed over Valentia Observatory in Co. Kerry.
Graphic of MSLP (pressure) below.
Central pressure was 959hPa#Ophelia pic.twitter.com/MTUIGKvsa8

— Met Éireann (@MetEireann) October 16, 2017

Roof of Cork City's football stadium blows off as Ophelia batters south of Ireland https://t.co/szvfgPnIWP pic.twitter.com/KdYvim9hcH

— Independent.ie (@Independent_ie) October 16, 2017

Dramatic footage of the roof being blown off #Douglas Community School's gym on southside of #Cork city #Ophelia #iestaff pic.twitter.com/0dSw5w1rTj

— Eoin English (@EoinBearla) October 16, 2017

Coastal defences completely breached at Salthill, Galway. The Atlantic now extends to the promenade. #Ophelia pic.twitter.com/qF9B47Ty3i

— David Blevins (@skydavidblevins) October 16, 2017

Irish Eyes Aren't Smiling

Hurricane Ophelia has had an unusual life cycle in the northeastern Atlantic Ocean and as of 11 AM AST this morning, was still a category 1 hurricane off the coast of Portugal. 

Source: National Hurricane Center

Over the next 24 hours, Ophelia is expected to undergo what is known as extratropical transition, the transformation from a tropical cyclone into an extratropical cyclone.  It is expected to track northeastward and bring strong winds to Ireland and Scotland on Monday. 

The GFS sea-level pressure and wind speed (meters per second) forecast from the GFS is below and it shows the storm strengthening and broadening just southeast of Ireland, before weakening just a bit prior to landfall. 

Nevertheless, the system is quite strong at landfall.  The areas in yellow feature sustained winds of 28 m/s (56 knots) and orange around 35 m/s (70 knots), the latter are hurricane force.  These areas are found over water.  Winds are weaker over land, but still quite strong. 

The Irish Meteorological Service, Met Éireann, has issued a National Weather Warning and is expecting sustained winds of 80 km/h (43 knots) and gusts in excess of 130 km/h (70 knots) in the southern half of the country.

Source: Met Éireann, 9:30 MDT 15 Oct 2017

Much will depend on the precise track of the storm, but it looks like this will be a strong windstorm for Ireland, and perhaps Scotland and other portions of the UK. 

The Waiting Game Begins

Last night's trough passage brought a couple inches of snow to the upper elevations of the central Wasatch.

Source: Snowbird

Even at my place, there was a trace of snow. 

The waiting game now begins for the start of the ski season.  As things stand now, the next five days look dry.  Although cold today, we should see marvelous fall weather beginning tomorrow through at least Wednesday and probably Thursday as well.  

After that, we shall see.  The good news is that the GEFS is calling for troughiness over the western US late next week.  

However, snowfall in the Wasatch is greatly dependent on all sorts of factors that cannot be nailed down so far in advance.  Some of those solutions would probably give us a pretty good dump, others next to nothing.  

Thus, at this stage, it's best not to buy into any click bait based on extended range forecasts. 

Need a Recommendation

I've discovered some minor damage to my carbon fiber mountain bike frame.  Recommendations for affordable repair shops or individuals greatly appreciated. 

Abrupt Changes This Weekend

Mid October arrives on Sunday, meaning that I begin to take a closer interest in potential storms that could bring the start of ski season.  

The trough moving through tonight and tomorrow won't bring more than some light accumulations to the central Wasatch, so the ski watch continues, but it will bring some rapid changes in upper-elevation temperatures.

While we have fall-like weather today, by 1200 UTC  (6 AM) tomorrow morning, a fast moving upper-level trough ushers in some legitimately winter-like air, with 700-mb (10,000 ft) temperatures at or below -10ºC by tomorrow morning.  That's pretty frigid for October.

But by 1200 UTC (6 AM) Sunday morning, we've rebounded nicely to +2ºC. 

Here's the yo-yo as illustrated by our automated temperature forecast derived from the NAM for the summit of Mt. Baldy (11,000 feet).  Temperatures today in the low to mid 20s (the station currently shows 25ºF), but plummeting overnight to 8ºF by 8 AM.  Temperatures climb, however, as the trough moves out and the ridge moves in and by Sunday morning, they are pushing 40ºF.  

Bottom line: Tomorrow is good for sleeping in, enjoying brunch, and shopping for skis.  Save higher altitude adventures for Sunday.  Those adventures, however, won't involve skiing, at least in the central Wasatch.  

Sad Reminder that Early Snow Is Not Necessarily Safe Snow

It's very early in the ski season, yet a backcountry skier died in an avalanche on Imp Peak in the Madison Range of Montana on Saturday.

Source: Friends of the Gallatin National Forest Avalanche Center

Some basic information is available in this article from the Bozeman Daily Chronicle.

This is a sad reminder that early snow is not necessarily safe snow.  The central Wasatch has had early season fatalities in the past, including within resort terrain, which is de facto backcountry during the preseason.  Keep this in mind when we start to see snow piling up again.  

Cold Blast to Start Fall Break Week

Don't be fooled by today's mild temperatures.  A blast of cold air will move into Utah tomorrow and yield some unseasonably cool temperatures on Monday for the start of the U's Fall Break week. 

The NAM forecasts the dry surface front to be pushing through northern Utah early tomorrow morning, so tomorrow is a day during which temperatures will struggle to rise. 

By Monday morning, the upper level trough is centered near Vernal and 700-mb temperatures are dow to around -7ºC. 

Such a temperature wouldn't be a record based on historical upper-air soundings, but is well below average. 

And the NWS forecast shows how the bottom drops out after today. 

Monday looks to be a below average temperature day statewide.  Pity this system looks to only produce some snow showers and perhaps an inch or two of snow in the central Wasatch.