Wasatch Weather Weenies

Based on visible satellite imagery, the West Desert was the big producer today.  As is often the case, just a few wispy clouds can complicate dust detection and that was the case today.  Nevertheless, I've highlighted below a few areas where on can see evidence of plume initiation in the late-day satellite imagery. There's also a very nice image MODIS that shows the plumes over the West Desert this afternoon.  Click to enlarge and you can also see a plume extending from the Skull Valley over the Great Salt Lake.  If you look really carefully, there seems to be some dust over the Tooele Valley that may be related to strong winds over and downstream of South Mountain. 2020 UTC 31 Mar 2012 Aqua/MODIS image The origin of the dust over the Salt Lake Valley is a bit more of a mystery.  There's not an easily identifiable plume that we can trace upstream.  There may be a number of smaller point sources, as suggested in the top satellite image above. ...

It appears we've at least tied if not broken the all-time record high for March at the Salt Lake City International Airport.  It was 78ºF until today.  It appears we've reached 79ºF so far. I'd say wow, but after seeing what happened in the east a couple of weeks ago, this seems pretty tame.  Further, over the next few decades, we'll leave this in the dust. Speaking of dust, things are just starting to get interesting.  I can't see the Oquirrhs anymore and the Wasatch are starting to look a titch fainter. I suspect the entire valley will be enveloped eventually as the large-scale flow should gradually shift to southwesterly and put us in the dust-plume cross hairs. On a weekend like this, the Wasatch Weather Weenies are like pigs in slop. Source: amarkonmywall.wordpress.com

Click on the above for a higher res version, but what a beautiful loop of the frontal cloud shield penetrating across the Sierra-Cascade ranges and dust in the southerly and southwesterly flow ahead of the front. I've indicated with boxes a few areas where plumes are visible, the most impressive being the Carson Sink of western Nevada which is absolutely lit up right now.

Thusfar, the central Wasatch have escaped the wrath of the dust, but that's not the case in the western Salt Lake Valley and southern Oquirrh Mountains, as evident in the image above, which was taken facing south from the Avenues.  Note the obscuration in the right half of the image. One of the most prominent plumes thusfar today is to our west, appears to originate in the Skull Valley (near the diamond I've annotated), and blows off downstream over the Great Salt Lake. There's a chance this is smoke and not dust, but I can't imagine anyone would be burning anything today with so much lead time for the high winds.  The UDOT cameras also suggest it is dust. Thusfar, we've had a wind gusts over 50 miles per hour at several stations in the lowlands of northern Utah, with a maximum of 62 miles per hour out in Dugway Proving Grounds.  I think we'll see higher gusts over the next few hours as the storm intensifies.

Looks like a hot and dusty day is in store for today.  The day has dawned with a mostly clear, remarkably dry airmass in place over the Intermountain West. Source: NCAR/RAL The NAM time-height section for Salt Lake City (time increases to the left) shows dry air (relative humidity < 30%) aloft and in the lower troposphere (<70%, including near 30% at the surface).   NAM relative humidity (color fill), wind, and equivalent potential temperature analysis (contours) Actual surface relative humidities will likely be even lower than indicated by the NAM.  And, the NAM forecast for this afternoon shows strong southwesterly flow over Utah. All of this adds up to a hot dusty day.  Hot in this instance is relative to climatology.  The all-time record high for March is 78ºF and we'll make a run at that today.  I think something close to that is likely.  Some have called for a high in the 80s.  While that's not impossible, I thin...

Source: ESPN Given that it is Final Four weekend, I'm naming our pending storm "One and Done," as in  one monsterous airmass change . The latest GFS calls for tomorrow to be warm and windy.  Crest level (700-mb) temperatures tomorrow are forecast to be near +6C at Salt Lake City, which would be the warmest airmass we've seen thusfar this Spring. We'll probably see a high temperature at the Salt Lake City airport near 78ºF, which is the all-time record high temperature for the month of March.  Time will tell if we go into uncharted territory.  Blowing dust is likely, although we'll have to see if the trajectory is right for Salt Lake and the central Wasatch to get hit. The GFS brings the surface front between midnight and 6 am on Sunday.  Should that verify the temperature change will likely still be impressive, but not as large as it would be if it came through in the afternoon.  You can't have everything! By noon Saturday, the forecast cres...

The Intergovernmental Panel on Climate Change (IPCC) has just released a Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (a.k.a. SREX).  The Summary for Policy Makers and Full Report are available here .  Ignore the press coverage and go straight to the source.   I haven't had a chance to fully peruse the report, which is more than 500 pages long (surely you will all consume and digest this by tonight).  However, since we have been talking the past week about heat waves and snow records, I thought I would summarize some of the key findings with regards to trends in extreme events:  "There is evidence in observations gathered 1950 of change in some extremes. Confidence in observed changes in extremes depends on the quality and quantity of data and the availability of studies analyzing these data, which vary across regions and for different extremes." "It is very likely that there has b...

Source: calypsocom.com Following up on the previous post  and comments, I'm now a full-blown skeptic when it comes to the Tamarack, CA seasonal snow depth record of 451 inches, as recognized by the National Climate Extremes Committee .   When I say I'm a skeptic, I'm not dismissing it, I'm just saying that I'd like to see stronger evidence as the data available online from the National Climatic Data Center (NCDC) simply does not support such an extreme number, especially if it is supposed to represent the settled snow depth on level ground in a wind-sheltered area.  Ditto for other records from Tamarack. What we need is an ambitious weather historian to follow the paper trail and possibly do some additional analysis of all the available data from the Sierra Nevada, including the historical archives from that era (e.g., newspaper, etc.).  Sorry kids, but you can't do all this on the Internet, which is precisely why I'm going back to running my computer...

Sounds like an easy question, but the answer isn't so simple.   I figured I'd go to the National Climatic Data Center, and sure enough, I found a web page for "National Snowfall and Snow Depth Extremes."  Ah, an answer. Source: NCDC But, years of wasting time reading about snow caused me to scratch my head about the numbers above.  I seemed to recall that California had some prodigious snowfalls.  Indeed, it's easy to find web sites with conflicting numbers from California.  In particular, many claim that the monthly snowfall record is actually 390 inches at Tamarack, CA in March  January 1911 and the single storm snowfall record is 189" at Mount Shasta Ski Bowl from Feb 13–19 1959.   I'm not sure why the difference in the monthly snowfall record, especially since it appears the NCDC data above includes an analysis of March 1911.  Perhaps the March 1911 data was deemed suspect?  I also wonder if the Mount Shasta record mi...

The medium range forecast models suggest we could see an April Fools' Day dump.  The GFS forecast looks especially nice. I'm tempering my excitement given that this is a 5-day forecast, but I'm also thinking I'm going to be keeping the skis waxed and ready.  When it comes to powder, I'm no fool...

Gorgeous stuff being generated over Lone Peak and environs in the large-scale southwesterly flow. 

On average, April is the wettest month of the year at the Salt Lake City International Airport and, although it is only March 26, it sure feels like the beginning of the "rainy season" today.  It's dark out, windy, and the rain is pelting the windows of my office, which face south.   I also think I saw a flash of lightning produced by the cells that were located in the eastern Salt Lake Valley earlier this morning. Temperatures dropped like a rock at the University of Utah this morning.  After holding near 56ºF for much of the night, we're now at 37ºF. There was a 51 mph wind gust at 8:15 too. Yup, the rainy season is officially here.  Enjoy.

To followup on our discussions of the heat wave in the eastern US, Stefan Rahmstorf and Dim Coumou have just posted a discussion of linkages between global warming at heat waves at RealClimate .  They have a recent paper on this topic , although it's cost-for-access.  Those on the University of Utah campus should be able to access it for free due to our campus license.

One of my favorite Seinfeld episodes is  The Opposite , in which George Costanza realizes that every instinct he has ever had is wrong, and vows to do the opposite, with grand results.  I often tell students, especially those who are used to the meteorology of the eastern United States, to take such advice to heart.  Often, the weather here works in ways that counter your every instinct.   Tonight and tomorrow offer a straightforward example.  The NAM forecast for midnight tonight shows that the flow over Utah is from the south at the surface and 700-mb.  Instinct says it must be bringing in warm air right? Wrong Costanza, do the opposite!  This is a situation where cold air pushed southward off the California coast the past couple of days and will swing into Utah from the southwest tonight and tomorrow.  As a result, that southerly flow is bringing in cold air.    And, it will give us a changeable day tomorrow with ...

My head is still spinning from the heat wave in the eastern United States (not to mention Canada).  The Weather Underground has a nice web page for examining weather extremes, including high temperatures, low temperatures, rainfall, and snowfall here , with an example of all-time monthly temperature records set on March 22nd shown below. Source: Weather Underground Enjoy a look at this extraordinary event.

Incredibly, even though the high temperature at the Salt Lake City International Airport was 71ºF yesterday and the weather station at the top of the Collins Chair at Alta (10,400 ft) reached 43ºF, there was still some settled powder to be found in the Wasatch Mountains this morning. Where?  Up very high on an aspect that faces due north.  I mean right on the north compass point.  Going even just a smidge off that compass point and you'll be dealing with a sun crust or manky snow depending on the time of day. How is it that powder can survive when the free air temperature is above freezing?  First, the air is very dry.  The dewpoint temperature at the top of the Collins Chair at Alta, which we'll use as roughly representative of the highest elevations in the Wasatch, has lingered in the mid teens for the past couple of days. As a result, while there is some heat flux from the atmosphere to the snow, there is also a net loss of energy because the s...

I've been looking at the heat in the northeast and it is truly mind boggling.  The Snowmiser has clearly seceded ground to Heatmiser. Yesterday's high temperatures are ridiculous. Source: Hamweather.com Burlington, Vermont hit 81.  Their old record for the date was 68.  Bangor, Maine reached 83!  83 in Maine in March, are you kidding me?   Their old record was 64.  Caribou, Maine made it to 73 compared to an old record of 57.  How about these ridiculous numbers from Michigan.  The high in Marquette was 81.  Their previous record high was 49 (although their climate period only goes back to 1961).  In fact, the minimum temperature in Marquette yesterday was higher than their record high temperature. Source: NWS Then there's some web cam photos from northeast ski areas.  First, Hunter Mountain, Snowmaking Capital of the World. Source: Hunter Mountain Killington, Vermont, where I once skied in June. Source: Ki...

Some wild stuff is happening back east.  Unbelievable temperatures in the northeast.  Burlington in northern Vermont hit 80ºF yesterday, the earliest occurrence of 80 degrees in the historical record, which dates back to 1883.  In fact, it breaks the old record by 9 days and is only the 6th 80 degree day ever observed in March.   Today will be the fourth consecutive day of "crazy warm" temperatures. In fact, as of 10:30 AM, the current temperature of 69F was already a record for the day. Win Smith, President and owner of Sugarbush ski area describes the situation well in his blog post from yesterday .  Actually, I found this post to be quite forthcoming and lacking the sort of candy coating that one often sees on ski area web sites.  Of course, New England skiers have always enjoyed whatever skiing they can get.  Kudos to them.

Here at the Wasatch Weather Weenies, our posts typically concentrate on the science of mountain weather and forecasting.  Although we often discuss the forecast, education and outreach is our primary mission and objective.   Looking for resort-specific forecasts for the Wasatch Mountains?  You might consider checking out UtahSkiWeather.com , a web site run by Atmospheric Sciences students at the University of Utah that provides forecasts for every resort in Utah as well as the Wasatch backcountry.  Have a look, but be sure to come back to the Wasatch Weather Weenies for the geeky stuff.   And, for you University of Utah snow geeks out there, Ned Bair of UC-Santa Barbara will be giving a seminar tomorrow (Wednesday) at 3 PM in 110 INSCC entitled "A Field Study on Failure of Storm Snow Slab Avalanches."  The seminar specifically examines the mechanisms of avalanches in new snow that has net yet undergone metamorphosis into faceted or rounded grai...

If you aren't skiing today, my advice is that you call in sick tomorrow.  Whatever humans haven't tracked and trashed today, Mother Nature is going to take care of the next couple of days. The GFS is calling for a rapid rebound in 700-mb (crest level) temperatures to -4ºC by late tomorrow afternoon and 0ºC by Wednesday afternoon. For the powder on all but shady upper-elevation northerly aspects, this means easy come, easy go.  Our brief flirtation with winter is almost over.  I'm heartbroken already, but it is better to have loved and lost than never to have loved at all.

Kevin Hammonds Finally!  A decent day of backcountry skiing.  In fact, it was probably my best day of the year as I missed the last decent run of powder thanks to a balky back.  Conditions were quite good above 9000 feet and not bad below that, although it got a tad stiff at elevations that were in the melting band during the snowfall late yesterday and overnight.  Even south aspects skied well thanks to the persistent cloud cover.   Most of our turns were at elevations above 8500 feet. Looks like about 23" now at Alta-Collins since yesterday afternoon.  I'd say more like 10-12" where we were today, but that was enough given the right-side-up density profile.

Sometimes I love when a forecast busts.  Sometimes I don't.  I'm not sure what to think of this one.  It's been a crazy night. The Utah Avalanche Center reports 13–16" in the Cottonwoods, 8–10" in the Park City mountains, and a trace–2" in the Ogden and Provo area mountains.  That distribution reflects the fact that beginning in the late afternoon yesterday, a persistent, localized band of precipitation setup and really hit the central Wasatch, as discussed in posts from yesterday. Temperatures and snow levels have been high, but are falling this morning.  Nevertheless, given how high they were for much of the night, there's a huge contrast in the snowfall as you move from about 7500 to 9500 feet.  Location and altitude dictated accumulations overnight. We stopped getting data from Alta-Collins at 5 am, but at that time, there was 14" of snow produced by 1.51" of water since things got going yesterday afternoon.  That is a lot of water wei...

As suggested in a comment from one of our readers, perhaps the luck of the Irish is shining on us tonight. There is still an area of precipitation sitting over the central Wasatch, Mount Timpanogos, and environs. Source: NCAR/RAL It's really quite remarkable.  The northern Wasatch, which sometimes does well in southwesterly flow, has been largely skunked.  Keep in mind that snow levels are still quite high, so accumulations are minimal below 8000 feet, but it's piling up in the higher elevations, with 8" since 2 PM at Alta-Collins with .94" of water.  Yeah, it's Cascade Concrete, but who are we to be choosers this year?

The dust is finally here, at least in the western Salt Lake Valley as the Oquirrhs are becoming obscured. And, good fortune continues to shine on the upper Cottonwoods and environs as that precip band is just locked in. It's pretty warm up there, 29F at Alta-Collins and 35F at the base.  The snow level must be near 8000 feet.  Nevertheless, we'll take it, and it never hurts to start a storm with some high-density stuff.

For the past couple of hours, there has been a persistent train of echos extending along the southwesterly flow from southern Utah County across Mount Timpanogos, the upper Cottonwoods, and the Park City ridge line. At times, things looked quite sinister from the Salt Lake Valley, with some mammatus for a brief period of time (photo below a bit fuzzy, sorry...). Alta is getting quite a thumping, with .29" of water equivalent recorded from 1-4 PM, including .21" in the past hour, with 2" of snow (ignore the snow depth in the data table below). You never know where bands like this are going to setup.  You can see another one to the west side of the radar loop that's also been fairly persistent (but not as broad).  It's good to be lucky!  Hopefully good luck will shine further on us tonight. Addendum @ 455 PM Altitude is everything.  During the period above, Alta gets the goods, downtown Park City the drips.