Wasatch Weather Weenies

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, t...

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 ...

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 v...

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 fe...

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 ...

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 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...

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...

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 s...

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....

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 #Ophe...

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...

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...

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 ...

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.  

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.