.author-name { display: none; }
CODOS Update Feb 5, 2018: Snow School, Jan Recap, Delayed D1

CODOS Update Feb 5, 2018: Snow School, Jan Recap, Delayed D1

Greetings from Silverton,

February is well underway and the forecast to bring us out of our drought is not showing anything encouraging or productive in the near-term particularity in southern Colorado.  The current system moving through the Central Mountains may bring 8-12" to favored locations, while the Southern Mountains may see just a few inches.  The models are trying to decide what, if any, mountain precipitation we might see this Friday - Saturday.  

The plot below shows the number of storms we have received so far this winter season (red line) at Senator Beck.  Having received only 3 Storms so far marks a new low for our period of record (a storm is defined as at least 12 mm precip with no break in precip greater than 12 hours).  This is half the number of storms we experienced this time in WY2015 which was a dry year until 5 storms during May resulted in a huge recovery.  On average for this time of year we have already received 12 winter storms.  As winter progresses our chances of receiving the amount of storms necessary to bring us closer to a more normal dry year is diminishing.  Also too, it is not uncommon for just a few, very productive storms (or lack thereof) to make or break a snow season, but nonetheless these storms if we are going to receive them, are going to need to be more and more productive as the season progresses.            

Dust Event #1: After noting an intermittent dirty basal layer in the snowpack at certain locations for a few weeks now, we decided to log Dust Event #1 (D1) as occurring on December 20.  This is the likely date where we experienced sustained high winds out of the S-SW that preceded a precipitation event arriving December 21.  This faint dust has slowly shown itself not so much at Swamp Angel but other locations as noted by CSAS staff as well as observations from Colorado Avalanche Information Center.  Even though we have added our first dust event of the season to the record books this intermittent and diffuse dust, located at the very base of the snowpack, will have zero influence on spring snowmelt.  

Snow School: This is the last notice for "Snow School for Water Professionals" being offered Feb 28 - March 2.  There are still a few seats available for this combination classroom and field learning professional development opportunity.  Don't let the low snowpack scare you away, there are many unique and informative aspects to this snow season.  Please contact Jeff Derry or see our webpage https://snowstudies.org/field-education-workshops/

January Recap:  On Friday we posted a recap of our observations at Senator Beck Study Basin.  You can view the recap along with photographs and images on our Storm Reports page:  https://snowstudies.org/winter-storm-data/.  If you would like to receive email updates when these Storm Reports are issued please let me know.  In addition to our update the below links will take you to a number of other recently released weather and water supply updates:   

http://www.weather.gov/pub/climate2018WaterYear2018Comparison

http://www.weather.gov/pub/climate2018JanuaryReviewFebruaryPreview

https://www.cbrfc.noaa.gov/wsup/pub2/discussion/current.pdf

cumulative storm graph.jpg

CODOS Update Jan 2, 2018: December Recap, Snow School

CODOS Update Jan 2, 2018: December Recap, Snow School

Greetings from Silverton,

Happy New Year from the Center for Snow and Avalanche Studies.  We hope you had a fun and relaxing holiday season.  

Snow School for Water Professionals:  As a reminder, we are offering "Snow School for Water Professionals" again this February 28 - March 2, 2018 in Silverton, CO.  Using a mixture of classroom discussion and hands-on field sessions, this workshop is designed to enhance understanding of snowpack processes, snowpack monitoring, and snowpack data.  Please see attached flyer containing more details, and don't hesitate to contact me for more information.

December Recap:  We published a recap of December weather and conditions so far this winter  The Update can be viewed on our Storm Report page located here: https://snowstudies.org/winter-storm-data/

New Employee:  CSAS has had a new seasonal employee for the last year.  Phil Straub, is a Prescott College graduate and soon to get his M.S. degree with a dust-on-snow related thesis.  He also teaches avalanche courses for Prescott and Kachina Peaks Avalanche Center.  There may be occasions when Phil will issue a CODOS Update.  Please include Phil's email address (pstraub@snowstudies.orgto your "safe" contacts in your email settings.  We post CODOS updates to our website (http://www.codos.org/#codos) but we always issue an email notice when an update has been published.  And please follow us on Facebook and Twitter for dust-on-snow updates and general news about what we are up to.  

May your 2018 be peaceful and wet.

More Soon,

Jeff Derry   

CODOS WY2018: Snow School, DIA Exhibit, etc.

CODOS WY2018: Snow School, DIA Exhibit, etc.

Greetings from Silverton,

After another busy summer we are looking forward to the snow season to begin, hopefully sooner than later.  At Senator Beck Study Basin we define the start of winter as having at least 50% persistent snowcover.  Once the season kicks off expect the usual CODOS Updates and Storm Report Updates.  If you or your colleagues would like to be added to either of these e-mail update subscription lists, please contact me.  Otherwise you can view the updates at our websites,  http://www.codos.org/#codos and http://www.snowstudies.org/storms.html

Snow School For Water Professionals:  Once again we are offering Snow School for Water Professionals this year from February 28 - March 2, 21018.  This combination classroom and field course will begin on Wednesday morning at our office in Silverton and end on Friday afternoon.  This class is perfect for anyone wanting to learn more about the role of snow and our mountain systems as it pertains to water resources.  Attached is a flyer, please post in your workplace and please do not hesitate to contact me with questions.    

Denver International Airport Exhibit:  Yesterday I spent the day at DIA installing four informational display cases focused on CSAS, dust-on-snow, and the science we support at Senator Beck.  This three month long display is part of the Colorado Snow & Ice Exhibit and can be seen in the walkway towards Terminal A before you get to security.  If you walk from the Main Terminal toward Terminal A, you will soon see the display cases, so even if you intend to go through the main security gate, and have time, the display is still easy to view.  As part of the DIA effort, Christi Bode with Moxicran Media, made a 2-minute promotional video.  You will soon be able to view this video on the main page of the snowstudies website.  

Upgraded Website:  Within a few days we will have a new snowstudies.org website go live.  Initially, you will see pretty much the same content but with a new flare, but we have a number of improvements and new tools in the works that I will share with you as they become available.  

More Soon,

Jeff Derry   

WY 2017 Season Summary

WY 2017 Season Summary

SUMMARY

After a worrisome October and November when Colorado received very little precipitation and experienced very warm temperatures, winter finally kicked into action and Colorado started receiving abundant snowfall, building the snowpack rapidly during the months of December, January, and into February.  One of the big stories this winter season is the atmospheric rivers that fueled these productive storms, which were record breaking in some locations.  On the other end of the spectrum, one of the other big stories this winter is the observed warmest March on record.  The effects of this hot month (preceded by a very warm February) was a rapid warming of the snowpack and snowmelt at lower elevations and valleys, resulting in most stream gauges observed a 2-3 week bump in stream flow in mid-March thru the first part of April.  However, Colorado recovered from the hot/dry spell with a long stretch of regular precipitation beginning around March 23 – April 4.  A dry spell was again repeated April 5-19.  And, starting the latter part of April regular precipitation (however sparse) was observed steadily but intermittently until June 1.     

At the Center for Snow and Avalanche Studies’ (CSAS) Senator Beck Basin Study Area (SBB) at Red Mountain Pass, the primary Colorado Dust-on-Snow Program (CODOS) monitoring site, WY2017 produced a total of four separate dust-on-snow events, on the light side of a typical dust loading season based on observations going back to WY2005.  Dust season began relatively late in the season.  With the abundant moisture in the dust source area, the Southern Colorado Plateau, dust mobilization was kept in check until March when soils started drying out.  Dust-on-snow events March 5, 23, 31 and on April 9 were documented.  Surprisingly no dust events were observed the rest of April and May, although a couple haze events were noted.  On June 12 a big dust storm in the desert southwest was observed with the USGS dust cameras, additional dust on any remaining snow in the Colorado Mountains was not observed at lower elevations, but it is possible some higher elevation snow cover could have received additional dust from this event. Of the four documented dust events, two of these events were pretty heavy in their severity.  The end result, even though total mass loading of dust was light, with the location of the dust in the snowpack (i.e. upper portion) and its consequential role in snowmelt, we classified dust severity as “Average”, albeit the lighter side of average at SBB.  Northern and some Central CODOS sample sites in Colorado were classified as “Minimum” dust severity.  The transition from “Average” to “Minimum” severity took place in Central Colorado, thus some Central and all Southern CODOS sites were classified as “Average”.

CODOS Update June 17: Images of Dust Storm, Snow Gone at SBSP

CODOS Update June 17: Images of Dust Storm, Snow Gone at SBSP

Greetings from Silverton,

Snow cover at Senator Beck Study Plot (elevation 12,200') is gone as of today, June 17.  Remaining snow is mainly at higher elevations, northern aspects, and drift accumulation areas.  The Study Basin is now less than 50% snow covered, which translates, in our definition, to winter season 2016/17 officially coming to a close at Senator Beck.    Please see snow/streamflow/albedo plots below.  

On June 12 a major wind event hit eastern Utah and northern Arizona, and then western Colorado.  The dust that was kicked up was impressive.  With the wind/dust pulse coming in mostly in the evening and little snow at lower elevations, and the dust surface already being dirty in the San Juans, any new dust deposition was not immediately apparent, but a portion undoubtedly made its way to Colorado.  So maybe we can call it a "dust-on-remaining-snow-event" of little consequence.  We collected dust samples for USGS analysis following the event from the remaining sparse snow drifts.   

Please see attached photos from the USGS dust webcams (http://eldesierto.org/photoarch_index.html).  These cameras are maintained by Harland Goldstein and Frank Urban, which is a challenge under drastic budget constraints.  The CODOS Program is also grateful that Harland and his colleagues are willing/able to process our dust samples with no supporting funds to do so.  

Expect to see our Season Summary here in a few weeks.

AND HAVE A GREAT SUMMER!

CODOS Update June 12: SBB Conditions Update

CODOS Update June 12: SBB Conditions Update

There is still patchy snow around SASP, northerly aspects are still holding onto snow, but on June 9 snow was all gone under the snow depth sensor at SASP.  Red Mountain SNOTEL still shows 2.2" of SWE remaining.  With a day here and there of overcast conditions (June 3 & 7) seems to have taken the edge off the potential higher peak discharge rates at SBB that we saw last year.  And, yesterday, between 6am-11am average hourly flows were 14.6 cfs, and today they are 13.7 cfs.  So as of right now we are on track for less average daily Q than yesterday.   

I am guess-timating SWE at SBSP right now is around 12".  The snow sensor is showing 16" snow depth, but our study plot is more likely around 32" of snow depth.  There is less snow this year than at this time last year at SBSP - going by sensor snow depth data.  But, even so there is still a good amount of snow at higher elevations, I went on a hike above treeline over the weekend and appears there is decent snowcover and large snowfields above treeline.  

The tight gradient ahead of the approaching cold front is bringing windy conditions to eastern Utah, northern Arizona, and western Colorado.  Some desert webcams are showing hazy/dusty conditions indicating we might see some dust with this wind.  Fortunately, with the bulk of snowmelt behind us it will not be much of a factor as far as influencing snowmelt should we see it deposited in the mountains.  It might be slightly cooler today and over the next couple days, but it will remain warm and there is no stormy or overcast conditions in the forecast. 

CODOS Tour, Hot/Dry in Forecast

CODOS Tour, Hot/Dry in Forecast

Greetings from Silverton, 

The forecast last week called for mostly dry/warm conditions with potential storm activity in the mountains.  We have seen this play out at Senator Beck with a storm event (defined as 12 mm or more precipitation) late in the evening on June 1, and warm/sunny conditions dominating the last week of May and continuing to the present.  With average air temperatures increasing sharply so have minimum air temperatures, staying above freezing since May 29.  Consequently streamflows are near their peak snowmelt discharge levels, with recent discharge rates for some rivers being well above median levels (Animas, Rio Grande, Gunnison 1,000-1,500cfs above median.  Dolores ~500cfs.  Uncompahgre, San Juan, Lake Fork, Snake ~100-300cfs above median).          

We recently visited a handful of CODOS sites; Berthoud Pass, Loveland Pass, Hoosier Pass, and Wolf Creek Pass.  We documented current state of the snowpack and collected all-layers-merged dust samples for USGS analysis.  General observations are that as expected SNOTELS are near melt out, but above the elevation band that SNOTELS are located, the general landscape still has a good amount of snow left to melt.  And, looking at SBSP (12,186’) there is still 32” (80 cm) of snow depth and an estimated 17” of SWE.  Please see pictures below.

CODOS Update June 1: Snowmelt Continues, Warming Expected Into Next Week

CODOS Update June 1: Snowmelt Continues, Warming Expected Into Next Week

After D1-4 resurfaced across the majority of the landscape on May 26, and a start to the weekend of variable weather bringing a little precipitation, cooler temps and cloud cover, the last few days have seen sunnier/warmer temperatures, further degradation of snowpack albedo, and slight to significant increases in streamflows across the state.        

Many streams are near their median peak time-frame and, for this time of year, there is still a good amount of snow to melt.  With D1-4 now at the surface, where it exists (please see May CODOS report for spatial coverage of dust events http://www.codos.org/codosupdates/may92017), it is unlikely we will receive enough additional precipitation in the form of snow to cover dust for more than a day.  With the season's accumulated dust now persistently at the snow surface, we can expect continued albedo degradation enhancing snowmelt due to increased absorption of solar radiation.  That said, weather the remainder of the snowmelt season will be a determining factor in how streamflows play out.  Overcast conditions will slow melt rates, which there are chances of in most mountainous regions over the next few days.

CODOS Update May 26: D1-D4 Resurfaced at Senator Beck, Elsewhere

CODOS Update May 26: D1-D4 Resurfaced at Senator Beck, Elsewhere

On May 21 we reported 1' of new snow accumulation with 1.7" additional SWE at Senator Beck Basin (SBB) - with Colorado as a whole benefiting from a productive weather system May 16-18.  Over the last few days the merged dust layer consisting of D1-D4 has slowly showed itself in certain areas of the landscape.  And, this morning at Swamp Angel Study Plot (SASP), we observed D1-D4 to once again be located just slightly beneath the snow surface from ~2 cm new snow accumulation last night, but will most definitely be fully exposed later this afternoon at SASP as well as essentially all of the surrounding landscape with the exception of high elevation north facing terrain. Observed SWE at SASP is 20.4", down 1.2" from our last observation on May 19.   

After Colorado experiencing a warmer than normal February, the warmest March on record, and an overall warmer April, it was reasonable to assume we would be in for an early snowmelt.  But, in a fashion very similar to May 2016, May 2017 is shaping up to be cooler than normal with greater than average precipitation.  Much like May 2016, we have experienced a number of stormy periods that brought decreased air temperatures, overcast conditions, and additional snow which provided additional SWE as well as albedo re-sets to the snowpack by temporarily burying the concentrated dust layer.  Last year, stormy periods temporarily buried concentrated dust layers until May 31 when we reported full dust exposure in all dust impacted areas of Colorado.  With this dust exposed, along with persistent very warm/sunny weather, streamflows surged and we observed peak discharge (record peak) at SBB on June 6, as did many streams around Colorado.  At this point in time Senator Beck SWE conditions are very near where they were this time last year, as is streamflow, and dust conditions are classification the same as last year (average) - although this year is more on the lighter side of average.  Statewide, streamflow dropped last week to below median values with the addition of new snow in all mountain ranges.  This past weeks' warm temperatures have brought flows up to near or median values again in nearly all basins in Colorado, and with the weather in the forecast we can expect that steady rise to continue, especially after this weekend.  Even though the forecast is calling for periods of rain/snow over the next few days, it sure is starting to feel like summer.  The plot of streamflow and SWE may provide some plausible indication of how the remainder of snowmelt will unfold at SBB and elsewhere.     

CODOS Update, May 21: Dust Covered by 1' of Snow. 1.7" Additional SWE at SBB

CODOS Update, May 21: Dust Covered by 1' of Snow. 1.7" Additional SWE at SBB

Colorado is now solidly in the melt season with decreases in SWE in most parts of the state. Recent significant snowfall has slowed snowmelt driven runoff, but most CODOS sites statewide are well past peak SWE for the season, and it is likely that snowpack is increasing only at the very highest altitudes. In the Senator Beck Basin we are seeing losses in total SWE up to above 12,000 ft., even with this most recent snowfall.

In the last few days much of the state received significant snowfall as a large low-pressure system moved through the region. Here in the Senator Beck Basin we saw over a foot of snow with 1.4 inches of water, and similar values for precipitation are seen statewide.

Prior to this storm, merged dust events D1-4 were on the surface and notably lowering snow albedo. Additionally, snowpack in the Senator Beck Basin is mostly isothermal, meaning that higher elevation snowpack is beginning to contribute to runoff. For the time being, this new snow will cover the dust and raise the snow albedo again. This re-burying of the dust, along with cooler temperatures, is evident in hydrographs statewide, with discharge steadily decreasing across the region for the past few days. Currently discharge is slightly below median value for this date at nearly all locations in Colorado.
 

CODOS Update: May 17th

CODOS Update: May 17th

Greetings from Silverton,

Since our last CODOS update on May 9, streamflow at Senator Beck saw a 3 day down-tick (where we saw 1" of additional precipitation), followed by a 5 day up-tick when nicer weather returned.  As I write this Update, snow is lightly falling at Red Mountain Pass and in Silverton the sparse flakes do not accumulate and barely wet the ground.  However, the fresh snow and overcast, cooler temperatures, which is forecasted to intensify and continue the remainder of this week, will again slow snowmelt and consequently reduce streamflows temporarily.  The expected precipitation in northeast quadrant of the state is impressive, but the entire state looks to benefit from additional precipitation over the next few days.  Dry conditions are expected to return on Saturday as a warming trend takes hold for 2-3 days.  And encouragingly, the 1-month forecast calls for an increased chance of above normal precipitation.  SNOTEL data are showing major basins are still staying very near median values.

May 5-6 WY2017 CODOS Tour Update

May 5-6 WY2017 CODOS Tour Update

Summary

The CSAS team conducted another statewide CODOS tour May 5-6.  Fortunately we documented no new dust events over the last 4 weeks.  So far this season we have documented a total of 4 dust events, tying WY2015 for the least number of dust events observed.  However, it’s not so much the number of events that matter but the severity and timing of the events.  It just takes one moderate/severe event, deposited toward the end of the accumulation season to drastically effect snowmelt timing and rate for the remainder of the snow season.  So far this year, D3 (moderate) and D4 (upper end of moderate), occurred during this timeframe (March 31 and April 9), when maximum snow accumulation is largely reached in most watersheds, thereby allowing the dust to remain near or on the surface throughout ablation.  And as we like to mention often, spring conditions play a large role in determining when and how long the dust is exposed.  For example, since D3/D4 we have seen a number of stormy periods bringing additional snow accumulation, overcast and cooler temperatures, which temporarily cover the dust and slow snowpack warming and melt.  April is typically the month where we see the most dust events, then March, then May.  Even with April behind us, the dust-on-snow season is far from over.  Any dust events that were to happen now would immediately be exposed, or within a couple days, on the surface of the snowpack, adding to the dust presently on snow surface, further reducing albedo and increasing snowmelt rates.

Breaking News:  As of this writing a long duration dust event was observed in the Grand Junction area late afternoon on May 7th, the remnants of which have been noted in the Roaring Fork Valley.  Station data in the source area show sustained wind gusts from May 6-7, and webcams indicate dust in the Monticello region.  So, it looks possible dust event #5 has arrived in some locales (this morning observations at SBB reveal no new dust deposition), a day after the CODOS tour was completed (much like D4 on April 9).  Expect more information as to the severity and spatial extent of this potential dust event once field data and observations are collected.        

SNOTEL data indicate major Colorado basins are near their long term median SWE with streamflows, showing a spike from the hot weather these past 6 days, are still mostly considered within their median range.  The forecast is calling for more variable weather with plenty of chances of precipitation with cooler temperatures.  Please see streamflow and forecast discussion below.    

Colorado Dust-on-Snow Conditions

Dust conditions around the state were mostly how we left it from our last CODOS tour April 7-9.  Colorado has not received any new dust events over the last month, albeit we possibly experienced one or two “haze” events in some locales, which, if any minor deposition occurred at all, it would be indistinguishable from the dust already on the surface of the snowpack.  To recap the four dust events this year; dust event #1 (D1) occurred on March 5, and D2 occurred on March 23, both of these events were very light and mostly unnoticeable for a few days after deposited until finally showing itself throughout the landscape.  D3 came in on March 31 and classified as moderate at SASP.  On April 9, the last day of our CODOS tour, a large part of Colorado received D4, which is considered to be in the upper end of moderate to lower end of severe category.  D4 was a “dry” event being transported and deposited without precipitation.  Dry events are characteristically deposited in preferential locations wherever the wind transports and releases the dust, such as depressions on the snow surface, leeward slopes, and treed depressions.  Some locales came out of the last 10 days of April with dust layers covered under a few inches of new snow, other areas like the Rio Grande basin did not see much, or any accumulation, so dust was already exposed when the warming trend over the last few days started.  Currently, at most CODOS sample sites, dust layers are now merged at the surface.           

Changes in dust conditions, however, were observed at Berthoud and Willow Creek where, either through receiving indistinguishable amounts of just one dust event or all four, over time with snowmelt has allowed this light dust to coalesce at the surface, making it visible across the landscape.  This dust does not change the “minimum” dust classification at these sites, but will play its usual role in reducing albedo and increasing the amount of solar energy absorbed into the snowpack.  In the table below we summarize snowpack and dust conditions as well as provide plausible prior year hydrographs, updated from what was reported last month, that might help shed light on what to expect the remainder of this snowmelt season.   Links to these hydrographs are available at the bottom of this report.  

CODOS Update

CODOS Update

Greetings from Silverton, 

The series of storm systems beginning April 24 that tapped the brakes on a rapid snowmelt, as well as added a bit more SWE to the snowpack, is due to phase out by Tuesday.  The last ten days of April precipitation favored the northern mountains, with Rabbit Ears SNOTEL seeing 3.6” SWE, Grizzly Peak near Loveland Pass gaining 1.2”, Scholfield 1.4”, Grand Mesa 0.6”, and Red Mountain Pass 1.0”.  Some locations saw a decrease in SWE, such as Park Cone (-0.9”) and Wolf Creek (-1.2”).      

CODOS Update April 24: Dust Conditions, Snowmelt Rates, & Unsettled Weather in Forecast

CODOS Update April 24: Dust Conditions, Snowmelt Rates, & Unsettled Weather in Forecast

As forecasted, the last ~19 days have been sunny, unseasonably warm, and mostly dry.  After a mostly warm March the snowpack statewide was 108% of normal.  Now, after a mostly warm/dry first two-thirds of April, average statewide snowpack conditions are 94% of normal.  When the heat was on the snowpack quickly responded.  In March, enthusiastic snowmelt was seen throughout the state and for a period it appeared most basins had seen peak SWE around March 1.  However a series of late March storms bumped SWE amounts creating a "double peak", with the second peak in most basins occurring around April 1.  Since April 1st we have seen rather high ablation rates.  Please see plots below investigating these warm conditions and increased snowmelt rates.    

No new dust events have occurred since the dry dust event (D4) on April 9. Dust layers D3/D4 have been exposed at the surface of the snowpack essentially since D4 was deposited. D4 was a dry event, occurring without accompanying precipitation. Dry dust events are more subject to preferential transport, meaning dust is deposited in thicker layers on lee aspects and in depressions in the snow surface such as old wind features. A haze event was observed April 14 but did not deposit a discernible amount of dust on the already exposed D3/D4 dust layers.  On April 20-21 we received a couple inches of new snow accumulation with 0.35" (9 mm) of precipitation.  This minor storm event provided an albedo reset and cooler temperatures over the last few days.  Now, at Red Mountain Pass D3/D4 is reemerged at the surface of the snowpack, and the patchier distribution of the dry D4 event along with the uniform distribution of D3 are both evident across the landscape.  Elsewhere around the state, with somewhat similar weather across mountain areas, conditions have likely unfolded in a similar manner where dust deposition was present (please see our April Tour Update http://www.codos.org/codosupdates/apr122017).   

 

Starting Monday, the forecast is calling for "unsettled weather" for the next ~6 days.  The result will be periods of showers, isolated thunderstorms, mountain snow, and at least cloudy conditions between storm systems.  Temperatures are expected to be below normal with the possibility of the snow line getting down to mountain bases.  With this expected precipitation it will be interesting what kind of third bump we'll see in the snowpack, the 7-day forecast calls for 1-2" of precipitation across Colorado, with northeast Colorado looking to finally receive some much needed precipitation .  It will also be interesting what sort of conditions May will bring, the last two years the month of May has been wet and cooler than normal, which was crucial not only in adding valuable SWE but also extending the snowmelt season to a near normal time-frame

CODOS Update: April 14 Haze, Chance of Precip in Forecast

CODOS Update: April 14 Haze, Chance of Precip in Forecast

Greetings from Silverton,

The past 6 days has seen an uptick in streamflow (some streams seeing close to double their median discharge) due to the warm/sunny conditions throughout most of Colorado with melt rates being exacerbated due to dust event D3 and/or D4 being located at the surface of the snowpack.  Around Red Mountain Pass, D3 and D4 are now merged in many locations and very close to merged at Swamp Angel.  During this time there have been a couple of windy days with gusts in the 20-30 mph range in the desert southwest, four corners region.  On Friday, April 14, these winds created enough disturbance to create a haze event in southwest Colorado.  Any dust that fell on the snow surface from this haze is likely negligible, as well as indecipherable with D3/D4 being located on the surface.  But, it is worth mentioning since these seemingly small events do incrementally add to the total dust load on the snow surface and contribute to further reduction of surface albedo.  

The forecast the next ~10 days is calling for a series of Pacific storms moving across the inter-mountain west.  Today winds will remain out of the southwest with strong gusts up north and lessening in the south, and warm temperatures continuing.  On Tuesday clouds will increase in the afternoon and bring chance of showers and maybe a few thunderstorms.  Snow levels could be in the 9,000' range Tuesday night.  Late Wednesday could see moderate accumulation in northern Colorado mountains and light accumulation in the central and southern mountains.  Another, slightly colder, system is due to move in Thursday thru Saturday continuing the chance of mountain snow and rain in the lower elevations.  All told, these systems are expected to bring periods with cloud cover and chance of precipitation, when these conditions occur will serve to lessen the solar energy input on the snowpack and possibly even cover the snow surface with clean, fresh snow, temporarily restoring high albedo to the snow surface.       

April 7-9 WY2017 CODOS Tour Update

April 7-9 WY2017 CODOS Tour Update

Summary

The CSAS team conducted the April CODOS tour April 7-9.  Dust event D3 is within the top 12” of the snowpack at the majority of CODOS sites, and as we were finishing the tour dust event D4, a dry deposition event that occurred April 9, was observed at Red Mt. Pass and Grande Mesa.  Judging by its intensity and the fact that it made it to Grande Mesa indicate chances are highly likely it is also at Wolf Creek, Spring Creek, Park Cone and McClure Pass.  Being the last storm system we received, and also being a mostly dry event, it is currently on the surface of the snowpack where it was deposited.   Locations that appeared to be dust free on April 9 are Willow Creek Pass and Berthoud Pass.  Loveland Pass received D1/D2 events but appears to not have received D3 or D4.  Hoosier Pass escaped D3 but it is uncertain if D4 reached that locale. 

At the onset of spring all of our CODOS sites boasted healthy above average snowpacks. Over our past two CODOS tours we have seen snowpack declines at many sites, with some significant losses in snow depth and snow water equivalent (SWE). Losses between the two CODOS tours were especially apparent at lower elevation sites and at sites with more dust deposition or dust at the surface of the snowpack.

We are posting the snow profiles collected and new photos on each CODOS site’s webpage, as well as hydrographs and SWE graphs.  Below you will also find a summary table and brief discussion for each CODOS location.  Using the Dust Enhanced Runoff Classification (DERC) approach, links to hydrographs of the CODOS sites from WY2006-2016 are collated and presented to help with ascertaining what this Spring runoff scenario might look like.  We anticipate at least one additional circuit of our ten CODOS sites this season as well as intensive monitoring at Senator Beck Basin (SBB).

CODOS Dust Alert: Event D4 WY2017

CODOS Dust Alert: Event D4 WY2017

Greetings from Silverton.

CSAS was on the road over this past weekend for our second CODOS tour of the season. We will be releasing a full report on this data collection trip in the next couple days, but for the time being we have received another dust event at our Senator Beck Basin Study Area in the San Juan Mountains.

Our fourth dust event of the year was a moderate dry event, lasting approximately 21 hours. The majority of the dust was likely deposited toward the end of this period. Currently dust is most apparent on North and East facing slopes in leeward areas where air tends to recirculate when wind blows over the landscape. The dust is also highly visible in other small surface features such as old ski tracks and tree wells.

CODOS Dust Alert: Event D3 WY2017

CODOS Dust Alert: Event D3 WY2017

Winter storm #22 is now at its end and it was evident at the onset of the storm that this precipitation was accompanied by our third dust event of the season.

D3 was a “wet” event (occurring with precipitation) that began March 30th at 1500 and lasted 15 hours, ending at 0500 on March 31st.  The dust is pinkish-red in color was deposited in a very visible layer that is diffuse in the lower 2-3 cm of snow from winter storm #22. Winds during the event were largely from the south and southwest. This is our most visible dust event so far this season, and likely our largest by mass load as well.

CODOS Update: Event D2, Snowpack at Swamp Angel Isothermal

CODOS Update: Event D2, Snowpack at Swamp Angel Isothermal

The set-up of the storm currently passing through Colorado was perfect for bringing dust to the Colorado snowpack.  Dust event #2 (D2) hit the San Juan Mountains near Red Mountain Pass yesterday, March 23.  Like D1, this event came with snowfall and is difficult to currently see, being diffuse in the new snow accumulation.  The wonderfully productive storm that brought dust also deposited 18" of snow containing 1.5" water at SASP.  We will elaborate on this dust event as conditions unfold and ascertain the spatial extent during out next CODOS tour in mid-April.  Since the majority of the dust likely came at the beginning of the storm, it won't take long to blend with D1 once the snow warms and consolidates.  And fortunately for the time-being we have 18" of new snow covering D1 and most of D2.  Eventually, the dust will become more prominent and concentrated at the surface when sunny conditions return.

Along with this dust event, finally, we are seeing a reprieve from the dry, warm, and sunny stretch of weather we have been experiencing since the last storm (and dust event) March 5-6.  Even though we have only logged one moderate dust event prior to today,  when the dust is exposed on the surface of the snowpack like D1, it only serves to increase the absorption of solar radiation that contributes to warming/melting the snowpack.  This is the time of year when we play the "albedo reset" game, where we pray for new snowfall to cover dust accumulated at the surface of the snowpack, to keep the albedo (or reflectance) of the snow surface high, thereby slowing warming and subsequent melting of the snowpack.  At the least we are grateful to see cloudy, overcast conditions that limit the amount of incoming solar radiation.    

CODOS Update

CODOS Update

SUMMARY

A storm on March 5th brought Colorado’s first dust-on-snow event of WY2017 (D1-WY2017).  Winds up to 100 mph were recorded in the San Juan Mountains.  The preceding months experienced a large number of high wind events, but the March 5th event contained the right elements to mobilize dust in the source area and transport it to the Colorado Mountains.  From March 13-14 CODOS personnel toured our 11 samples sites around the state documenting the presence/absence of dust.  Dust was observed at 7 CODOS sites, following a general south to north gradient of moderate intensity at SASP, Wolf Cr., Spring Cr., Park Cone, McClure Pass, Hoosier Pass, and Loveland Pass.  Dust was not apparent at Grand Mesa, Rabbit Ears Pass, Willow Cr. Pass, and Berthoud Pass.  With the continuous dry, warm, and sunny conditions since March 5th, and the forecast indicating more of the same, combined with D1 being located on the surface of the snowpack increasing the absorption of solar radiation, sets up the conditions where the snowpack has experienced accelerated warming and melt, which will continue until the next chances of precipitation and cooler weather arrive.  SNOTEL station snow water equivalent (SWE) data indicate major basins in Colorado are still in the “High” category, as defined by the CODOS Dust Enhanced Runoff Classification (DERC “Average” equals day median +/- 10%).  For gauging stations that are active this time of year, streamflow is showing an early season uptick in response to the last ten days of sunny/warm conditions.  In the southern part of Colorado some streams are running double their median discharge for this time of year, with two stations (Dolores at Dolores, San Juan at Pagosa) showing flows close to 4 times their normal rate.