Wasatch Weather Weenies

Most of what you read about Utah snow is entirely bogus and makes little sense meteorologically.  Yet another example of Zombie meteorology that needs to die is an article by Jeff Layton in the latest Alaska Airlines Magazine entitled Lake Effect : It’s almost unfair that Salt Lake City has so much excellent skiing at its doorstep, but there is a scientific explanation, my friend Andy Mars told us the next day as we rode one of Brighton’s lifts. The Wasatch mountain rise up from the east edge of town, and the massive Great Salt Lake flanks the city to the west. Winter storms extract moisture from the lake - which doesn’t freeze. The salinity of the lake water gives the snowflakes unique powdery properties, and they pike up in totals that regularly exceed 500 inches per season.   While it is true that Salt Lake City has a lot of excellent skiing at its doorstep, and the average snowfall in portions of upper Little Cottonwood and Big Cottonwood exceeds 500 inches, just ab...

Wasangelas and the Oquirrh Mountains.  Tuesday November 27, 2013 I was curious how the Thanksgiving day holiday would affect air quality in the Salt Lake Valley.  Answer: Not much.  PM2.5 levels continued to climb yesterday, with hourly averages peaking at 42 ug/m3 late yesterday and 24-h averages continuing to climb to 27 ug/m3.   Source: Utah Division of Air Quality Thus, Black Friday is aptly named this year.  There is a weak trough pushing into northern Utah for the weekend.  Hopefully it will stir things up a bit and provide some relief for the valley before the holiday weekend comes to a conclusion.  If not, there's always the mountains.   Personally, I feel fortunate to be out of town and breathing the cleanest air on Earth in southeast Alaska.  It is the rainy season here, but the car-wash-like conditions let up just enough to allow us to take a beautiful hike before overindulging on turkey and trimmings.  Happy be...

There will be no snow in Utah on Thanksgiving Day.  That's good news for everyone driving to Grandmama's house.  Right now, the first part of Thanksgiving weekend (Thursday and Friday) looks pretty benign meteorologically, but with some degraded air quality in the urban valleys.  There's a chance of some valley rain and mountain snow showers later in the weekend, but right now it doesn't look like it is going to add up to much.  Nevertheless, keep an eye on the forecast if you are traveling. For skiers, I'm sorry to say that this looks to be a weekend with snow primarily from hoses not heaven.  Natural snowpack in the upper elevations of the Wasatch presently sits at 50-85% of average.  At SNOTEL sites, Snowbird has the most robust snowpack with 4.4 inches of snow water equivalent (green line below).  That's actually right on the median for this time of year, meaning that half of the years have more, half have less.  Of course, by the time we ge...

With all quiet on northern Utah's eastern and western front this morning, and generally benign weather expected the first few days of Thanksgiving week, our gaze turns eastward to upstate New York and the Tug Hill Plateau where we are now gearing up for the National Science Foundation sponsored Ontario Winter Lake-effect Systems (OWLeS) project (see also The OWLeS Field Program: Adventures on the Tug Hill Plateau ). Although there have been some lake effect rain and "slush" events during the past couple of weeks, The Tug Hill just had its first significant, widespread dumpage, so our excitement level is rising. Source: northernchateau.com In addition, the National Science Foundation issued a press release on our activities on November 18, so we are not only busy with equipment preparations, but are starting to field calls from reporters. Source: NSF I suspect most Utahns won't bother making the trip (ha ha), but I know we have some upstate New York r...

Continuing with the living dead theme of the previous post, this is starting to turn into the zombie downslope windstorm.  It just won't die.  The UDOT portable tripod along SR-89 near Lagoon just had a wind gust to 67 miles per hour. Source: MesoWest Strong winds also persist from Olympus Cove to the University of Utah along the east bench of the Salt Lake Valley. Source: MesoWest Such winds aren't as strong as observed on Thursday night, but I'm sure they are getting annoying for those living in affected areas.

We are currently in a "lull" with regards to the strength of the downslope winds, but the Big Bad Wolf is expected to regain his lung capacity with the winds expected to intensify later today.  The National Weather Service has thus extended the high wind warning to noon Saturday. Source: NWS Gusts yesterday fell short of those observed in the 1 December 2011 event, but nonetheless were impressive and caused problems for travel by high profile vehicles along the Legacy Parkway and I-15.  The highest gusts (80 mph) were observed in the Centerville–Farmington area.  The 62 mph gust at the University of Utah is quite impressive.  I can't recall what our record is (maybe ~70 mph), but I always use 60 mph as the threshold for a significant event. Source: NWS Strong easterly winds along the Wasatch Front come in two major varieties: Gap winds or thermally driven exit jets that emanate from deep canyons like Parley's and Weber.  These winds tend to be con...

The strongest wind gusts of the event thusfar are currently buffeting the I-15 corridor from Centerville to Farmington. Source: MesoWest From south to north, here are the current gusts, with the peak gust noted if different CENWWS: 73 mph @ 5 PM MST (along Legacy Parkway just west of Community Park, Centerville) CEN: 56 mph @ 5 PM MST (along Legacy Parkway near 2150 N Centerville) UTPR0: 74 mph @ 5:10 PM MST (75 @ 4:30 PM MST) (just north of Lagoon on SR-89) Addendum @ 645 PM MST: CENWWS had a gust to 80 mph @ 5:30 PM

Like Napoleon, meteorologists know that nothing good comes from the east.  Most of the time, our weather comes from the west, so when it comes from the east, the pattern is unusual and anomalous and strange things happen. Wasatch Front residents are all too aware of what often happens when our flow comes from the east: downslope winds.  Indeed, we will be seeing a downslope wind event develop later today and amplify tonight as the large-scale flow between a developing ridge over northwest North America and a closed low near southern California strengthens and becomes more easterly.  This easterly flow is quite apparent in the NAM forecast valid 8 am MDT tomorrow (Friday) morning (although I've elected to show tomorrow morning, strong easterlies expected tonight too). Source: weather.utah.edu A closeup of the corresponding NAM 850 mb (~6500 ft) wind and temperature forecast for 1500 UTC (0800 MDT) tomorrow that time shows a low-level flow of cold air from...

An extremely difficult forecast period is on tap for northern Utah meteorologists.  The large-scale pattern is forecast to undergo rapid amplification with a major ridge developing over the northeast Pacific and northwest North America while a closed low forms off the coast of California.  This can be seen in the forecast dynamic tropopause (jet-stream level analysis) in the top image of the loop below, which covers the period from 11 PM last night through 11 PM Friday. These patterns are often difficult to forecast since the models really need to nail both the amplitude and the position of the developing systems in order to allow for a skillful assessment of local weather. Potentially in play the next three days are two major forecast concerns.  The first is the mountain snowfall expected later today and tonight.  The challenge here is determining where the fragments of precipitation making it into the Great Basin will end up and the productivity of the fro...

Following up on yesterdays post, I wanted to point to a presentation given by University of Utah Research Associate Kerry Kelly that is available here  and discusses the significant impact of wood burning on pollution in the Salt Lake Valley.  The talk is based on Kelly et al. (2013) , published in the  Journal of the Air and Waste Management Association . Here are the key points: 1. Wood smoke (and possibly cooking smoke) is likely the largest direct contributor (i.e., emitted from a source) to PM2.5 on winter days with PM2.5 > 20 ug/m3.  Note that our PM2.5 comes from these direct emissions and from chemical reactions involving other gases generated by combustion (such as nitrogen oxide).  The latter are typically referred to as secondary PM2.5. 2. Wood burning emissions are highly variable depending on their design, operations, and fuel, but they are far filthier than heating with natural gas. Source: Kelly et al. (2013) presentation ...

With fresh snow on the ground and clear skies currently over the Salt Lake Valley, you might not be thinking much about air quality today, but there is something that has been nagging at me since last week.  Perhaps the photo below will jog your memory. Smog over the Salt Lake Valley @ 7:20 AM on Wednesday 13 November 2013 As far as Salt Lake air pollution events go, last week's wasn't a biggie, primarily because the inversion wasn't intense (lack of snow cover) or prolonged.  Nevertheless, PM2.5 concentrations climbed throughout the week, with hourly averages peaking at 34 ug/m3 on the 13th and 24-hour averages peaking at 25 ug/m3 early in the morning on the 14th.  The National Ambient Air Quality Standard (NAAQS) is a 24-hour average of 35 ug/m3.  Although we did not reach this level, PM2.5 concentrations remained near or above 30 ug/m3 for much of the day on the 13th.   Source: Utah Division of Air Quality Nevertheless, during the entire event we...

Yesterday's storm delivered as promised.  The Utah Avalanche Center reports 10-15 inches in the Ogden area mountains, 12-14 inches in the Park City Area Mountains, 18-20 inches in Big Cottonwood, and 15 inches in Little Cottonwood.  The Alta-Collins automated stations recorded about 14 inches with 0.83 inches of SWE.  This is in addition to the modest 2 inches that fell on Friday. That's all great news, but I feel like I'm in a bit of a ski purgatory.  Alta and Snowbird have closed for uphill skiing.  Much of the terrain that had snow on it prior to the storm now has considerable avalanche hazard.  Much of the lower angle terrain that I typically ski in such situations was snow free or nearly snow free prior to the storm, or requires access via routes that were previously snow free.  Bony conditions abound.  The Utah Avalanche Center notes that a couple of injured skiers were evacuated out of the Albion/Catharine's area yesterday. Put some ...

The storm is here and it is snowing in the mountains, but I'm "snowblind".  Why?  The KMTX radar is out! Source: NWS Apparently there has been a major hardware failure and it appears that we may be without radar for the entirety of the storm. Source: NWS This is a huge handicap for nowcasting.  There's only so much you can do with satellite data, web cams, and precipitation gauge observations.  The good news is that the returns thusfar are encouraging.  Through 9am this morning Snowbasin's Middle Bowl observing site has observed 0.31 inches of SWE (all in the form of snow) since midnight.  Alta-Collins 0.13 inches of SWE with ~3 inches of snow, which gives 5 inches since yesterday.  Web cams show a beautiful scene at Albion Basin. Source: Alta.com The models suggest that mountain snow will continue through the day and into the evening.  Let's hope it does as we could use a major dumpage.  Be careful out there...

I love hiking in the early stages of a storm as the snow just begins to coat the ground, as was the case on my crack-of-dawn hike this morning.  There's something therapeutic about being wrapped in a good hard shell, having good traction to keep up a vigorous pace, and having wet snowflakes tickle the face. This morning's appetizer storm is also producing a beautiful scene up in the mountains, at least in the Albion Basin web cam at Alta. Source: alta.com The main course will arrive late tonight and tomorrow.  The latest model runs are drier than yesterday.  This morning's 12-km NAM has a forecast total accumulation from this morning through Sunday morning of 8.6 inches in upper Little Cottonwood compared with 20+ yesterday.  The GFS is a bit drier as well.  A big reason for the decrease is that the models are calling for the trough to be weaker and faster moving, and this ultimately puts the brakes on the post-frontal snowfall on Saturday night. ...

Numerical weather prediction models that are run on computers form the backbone of modern weather forecasting.  Over the past few decades these models have improved dramatically as they have become increasingly sophisticated in terms of their formulation, ability to resolve smaller scale terrain and atmospheric effects, and use of satellite and other observational datasets. Thus, critical to all forecasts is the use and interpretation of numerical weather prediction model output. Most forecasters use something called the forecast funnel to do this.  The approach typically involves an assessment of the large scale atmospheric structure (such as the strength and movement of pressure systems and fronts) and then a funneling down through smaller scales until one is considering a very specific local forecast. For a storm like the one expected this weekend, a forecaster examines data from several forecast models, such as the GFS, NAM, and ECMWF, as well as ensemble modeling ...

The model forecasts just seem to get better each day for this weekend's storm (with some mountain snow showers on Friday too).  Let's hope that they aren't just teasing us and that Mother Nature will ultimately deliver. Our potential savior system is an upper-level short-wave trough currently located just to the east of the Kamchatka Peninsula (X below).  It is expected to roll over the long-wave ridge and then dig into the northwest United States. The models have disagreed the past few days, but as things stand now, it appears that the GFS, NAM, and ECMWF agree that we will be seeing a storm on Saturday and possibly Saturday night (depending on how productive the post-frontal environment and lake effect prove to be).  Further, this is an event that looks cold enough to bring snow to the valley floor. It is a bit early to be thinking about snowfall amounts as a shift in the track of the upper-level trough could really screw things up (and perhaps the more excited...

One of the best ways to ensure a storm is to forecast dry weather, as done in the previous post ( Snow(Making) in Forecast ).  I came in this morning, pulled up the latest GFS, and lo-and-behold, the forecast for this weekend had changed.  Dramatically.   Here's the GFS forecast for Saturday afternoon that I used yesterday.  We are in the wake of a dry trough passage.   And here's the GFS forecast from this morning for Saturday afternoon. Yup, quite a change.  Keep your fingers crossed we get something.  Anything would make me happy at this point.  

Mild weather remains in the forecast through tomorrow (Tuesday) when the warmest air of the current dry spell is expected to move over northern Utah and 700-mb (10,000 ft) temperatures over the Salt Lake Valley peak at about +5ºC.  Tomorrow will be a good day for a foothill hike.   The past few days have been a serious setback for the snowpack.  It's now a do over for the south-facing aspects, which are snow free.  Snowmaking at the resorts has been limited or impossible.  Fortunately the sun angle is low enough that upper-elevation north-facing aspects are retaining most of their snow.   Forecasts for the next seven days show a shift in the pattern after Tuesday with Utah under the influence of cooler northwesterly flow.  The resorts should be able to get back to snowmaking, and I suspect they will be firing all the guns in their arsenals by later in the week when 700-mb temperatures are forecast to drop to near -7ºC.   I wish ...

My son and I got out for our first day of skiing today, opting for a "combat ski tour" at Alta where snow-covered (natural and artificial) north facing aspects were easily accessible.  Instead of first tracks and chin ticklers, we experienced first scratches and bone rattlers, but any day that my back allows me to enjoy snow, sun, and turns with my son is priceless right now. People in the snow business know that aspect is everything and that's very apparent right now.  Even with the warm weather, there's little if any snowmelt on upper-elevation north facing aspects, but the south-facing aspects across from Alta are nearly snow free.    Think more snow! 

With the Sochi Games coming up this winter, I recently dug out my slides from the Nagano Games and did some reminiscing.  The Salt Lake Olympic Committee (SLOC) sent me to Nagano to scope out weather observing and forecasting needs for the 2002 Olympics.  Being a pre-911 Olympics, I had credentials that provided unfettered access to the venues and a first-hand look at the events and weather needs for four jet-lagged days.  Most observation days involved a group visit and tour of a venue, watching an event, and then meeting with the venue meteorologist.  At a few venues, I met with former Olympians, coaches, or other support individuals to discuss the impacts of weather on the competitions.  Given the "boring" weather in place over Utah right now, I thought I'd share a few photos and perspectives. Enjoying a sunny day with Wasatch touring legend Dave Hanscom at the Snow Harp cross country venue in the Hakuba Valley.  The Japanese Alps rise more than 200...

Many people don't realize that the Great Salt Lake is a divided body of water, with each half operating almost independently from the other. This is not the natural state of affairs.  For centurys, water in the Great Salt Lake could move freely and without restriction.  Then, in the late 1950s, the railroad built an earthen causeway across the lake.  Although a couple of culverts were added to enable some mixing between the two haves, they have remained only loosely connected for many years and their chemical composition is dramatically different.  Most of the freshwater inflow to the Great Salt Lake enters the south half, so the salinity is lower (typically 9–12%) than found in the north half (typically ~28%).  This leads to differences in algeal and bacterial and water color between the two halves that can clearly be seen from space and the ground. The Great Salt Lake from space.  Source: NASA S135-E-006466. The Salt Lake Tribune reports this morn...