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Snow water content vs depth

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  • Chris
    I was checking out snow information on the CDEC web site and am somewhat unsure if my interpretation of the data is correct. For example the Bishop Pass site
    Message 1 of 14 , Apr 23, 2013
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      I was checking out snow information on the CDEC web site and am somewhat unsure if my interpretation of the data is correct. For example the Bishop Pass site (BSH) shows that snow depth has dropped from 14 inches since March 25th (from 34" to 20") yet the snow water content has increased from 14.20" to 16.40". My interpretation is that warm weather has turned soft fluffy snow into compacted slushy snow.

      Mr Ditti/Others - can you confirm?

      thanks, Chris
    • gkahn21
      Yes, your assumption is correct. When the snow melts it consolidates. Water content maxs out at about 50% of snow depth. This is something that happens every
      Message 2 of 14 , Apr 23, 2013
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        Yes, your assumption is correct. When the snow melts it consolidates. Water content maxs out at about 50% of snow depth. This is something that happens every year in the spring as the weather warms.

        Just checked now and the sensor says there is more water content than snow depth, which is impossible. Plus it would just be water at that point and run off or be a lake. Looked at last July's data to see what the value would be at null/no snow and water content was -13.03 inches so there might be something up with that sensor.

        --- In johnmuirtrail@yahoogroups.com, "Chris" <crhall41@...> wrote:
        >
        > I was checking out snow information on the CDEC web site and am somewhat unsure if my interpretation of the data is correct. For example the Bishop Pass site (BSH) shows that snow depth has dropped from 14 inches since March 25th (from 34" to 20") yet the snow water content has increased from 14.20" to 16.40". My interpretation is that warm weather has turned soft fluffy snow into compacted slushy snow.
        >
        > Mr Ditti/Others - can you confirm?
        >
        > thanks, Chris
        >
      • John Ladd
        I also think the sensor must be having a problem. 16 inches of water content in 20 inches of snow doesn t seem possible. John L
        Message 3 of 14 , Apr 23, 2013
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          I also think the sensor must be having a problem. 16 inches of water content in 20 inches of snow doesn't seem possible.

          John L

          On Tue, Apr 23, 2013 at 12:01 PM, Chris <crhall41@...> wrote:
           

          I was checking out snow information on the CDEC web site and am somewhat unsure if my interpretation of the data is correct. For example the Bishop Pass site (BSH) shows that snow depth has dropped from 14 inches since March 25th (from 34" to 20") yet the snow water content has increased from 14.20" to 16.40". My interpretation is that warm weather has turned soft fluffy snow into compacted slushy snow.

          Mr Ditti/Others - can you confirm?

          thanks, Chris


        • Ned Tibbits
          You got it right, Chris! What this will translate to (for all you snow-hikers) is that the pack is settling and consolidating and becoming more stable as the
          Message 4 of 14 , Apr 23, 2013
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            You got it right, Chris!
             
            What this will translate to (for all you snow-hikers) is that the pack is settling and consolidating and becoming more stable as the days grow longer and hotter, thus safer to walk on! Watch the nighttime temps. When they stop freezing, the creeks will dramatically rise as the pack melts out rapidly. Get your snow-hiking done early in the mornings and get off the pack before it becomes so soft that you start post-holing.
             
            Prepare for wet, creek-like trails below the snowline and mud most everywhere else. If the nights are still freezing, the creek crossing will be better, lower, but you’d better bring hiking crampons for those early starts on slippery snow/ice!
             
             
            Ned Tibbits, Director
            Mountain Education
            www.mountaineducation.org
             
            From: Chris
            Sent: Tuesday, April 23, 2013 12:01 PM
            Subject: [John Muir Trail] Snow water content vs depth
             
             

            I was checking out snow information on the CDEC web site and am somewhat unsure if my interpretation of the data is correct. For example the Bishop Pass site (BSH) shows that snow depth has dropped from 14 inches since March 25th (from 34" to 20") yet the snow water content has increased from 14.20" to 16.40". My interpretation is that warm weather has turned soft fluffy snow into compacted slushy snow.

            Mr Ditti/Others - can you confirm?

            thanks, Chris

          • Chris
            gkahn21, thanks for the info -should be useful in verifying the accuracy of the readings for a given site. Along this line I was surprised to see Sawmill Pass
            Message 5 of 14 , Apr 24, 2013
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              gkahn21, thanks for the info -should be useful in verifying the accuracy of the readings for a given site.

              Along this line I was surprised to see Sawmill Pass at zero snow depth. Is this site a good indicator for nearby passes on the JMT such as Pinchot and Glen?

              Chris

              --- In johnmuirtrail@yahoogroups.com, gkahn21 <no_reply@...> wrote:
              >
              > Yes, your assumption is correct. When the snow melts it consolidates. Water content maxs out at about 50% of snow depth. This is something that happens every year in the spring as the weather warms.
              >
              > Just checked now and the sensor says there is more water content than snow depth, which is impossible. Plus it would just be water at that point and run off or be a lake. Looked at last July's data to see what the value would be at null/no snow and water content was -13.03 inches so there might be something up with that sensor.
              >
              > --- In johnmuirtrail@yahoogroups.com, "Chris" <crhall41@> wrote:
              > >
              > > I was checking out snow information on the CDEC web site and am somewhat unsure if my interpretation of the data is correct. For example the Bishop Pass site (BSH) shows that snow depth has dropped from 14 inches since March 25th (from 34" to 20") yet the snow water content has increased from 14.20" to 16.40". My interpretation is that warm weather has turned soft fluffy snow into compacted slushy snow.
              > >
              > > Mr Ditti/Others - can you confirm?
              > >
              > > thanks, Chris
              > >
              >
            • richard long
              Is that Sawmill Lake or Sawmill Pass you are looking at? I can t see a station for Sawmill Pass, but there is one for Sawmill Lake.  In any case, I don t
              Message 6 of 14 , Apr 24, 2013
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              Is that Sawmill Lake or Sawmill Pass you are looking at? I can't see a station for Sawmill Pass, but there is one for Sawmill Lake.  In any case, I don't believe Sawmill Pass is really an equivalent indicator for Glen Pass, which is about 12K, and more of a west side Sierra pass that holds snow longer than Sawmill on the main crest.  I am attaching a photo from Lone Pine Lake(10K- Whitney trail) taken this past weekend. Snow levels are low for this time of year south of Forester, but there is still some snow.
              Regards,

              Richard Long
            • Chris
              Richard - it was Sawmill Pass. I believe the CDEC acronym is SWM. Nice photo btw - looking forward to seeing similar scenery in person in a couple months.
              Message 7 of 14 , Apr 24, 2013
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                Richard - it was Sawmill Pass. I believe the CDEC acronym is SWM. Nice photo btw - looking forward to seeing similar scenery in person in a couple months.

                Chris

                --- In johnmuirtrail@yahoogroups.com, richard long <rcarllong@...> wrote:
                >
                > Is that Sawmill Lake or Sawmill Pass you are looking at? I can't see a station for Sawmill Pass, but there is one for Sawmill Lake.  In any case, I don't believe Sawmill Pass is really an equivalent indicator for Glen Pass, which is about 12K, and more of a west side Sierra pass that holds snow longer than Sawmill on the main crest.  I am attaching a photo from Lone Pine Lake(10K- Whitney trail) taken this past weekend. Snow levels are low for this time of year south of Forester, but there is still some snow.
                > Regards,
                >
                > Richard Long
                >
              • richard long
                Interesting that the SWM sensor elevation is stated as 10,200 on the site. Sawmill Pass is about 11,400 . I don t recall seeing the sensor while I was there,
                Message 8 of 14 , Apr 25, 2013
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                  Interesting that the SWM sensor elevation is stated as 10,200' on the site. Sawmill Pass is about 11,400'. I don't recall seeing the sensor while I was there, but I always assumed it was closer to the lake, which is about 10000'. Please pass on the info if you get there this year and see the sensor, I like that area, and keep an eye on that reading.  In regards to the original question about crampons, if you are going in a couple of months, I believe it is highly unlikely that you would need crampons this year, unless there are some late storms. The last 500' before the pass narrows and has more shade, and  tends to hold some snow, but I doubt there will be much if any there in late June  this year. But that is just my opinion.

                  Richard Long
                • nedtibbits
                  Hey, just to add... Mountain Education will be on the JMT between Crabtree and Kearsarge May 13th to the 16th. We will let everyone know what the on-trail
                  Message 9 of 14 , Apr 25, 2013
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                    Hey, just to add...
                     
                    Mountain Education will be on the JMT between Crabtree and Kearsarge May 13th to the 16th. We will let everyone know what the on-trail conditions are like when we get back!
                     
                     
                    Ned Tibbits, Director
                    Mountain Education
                    www.mountaineducation.org
                     
                    Sent: Thursday, April 25, 2013 9:27 AM
                    Subject: [John Muir Trail] Re: Snow water content vs depth
                     
                     

                    Interesting that the SWM sensor elevation is stated as 10,200' on the site. Sawmill Pass is about 11,400'. I don't recall seeing the sensor while I was there, but I always assumed it was closer to the lake, which is about 10000'. Please pass on the info if you get there this year and see the sensor, I like that area, and keep an eye on that reading.  In regards to the original question about crampons, if you are going in a couple of months, I believe it is highly unlikely that you would need crampons this year, unless there are some late storms. The last 500' before the pass narrows and has more shade, and  tends to hold some snow, but I doubt there will be much if any there in late June  this year. But that is just my opinion.

                    Richard Long

                  • Chris
                    I received this personal email from someone in our group (did not provide a name) which seems very informative so I thought it would be good to share with the
                    Message 10 of 14 , Apr 25, 2013
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                      I received this personal email from someone in our group (did not provide a name) which seems very informative so I thought it would be good to share with the JMT group as a whole.

                      Chris

                      * * *

                      Chris, actually there are a few things going on to think about when looking at snow depth and snow water content. Yes, snow consolidates (becomes more dense) over time due to self weight of the snow above, freeze/thaw cycles, and other processes. Consolidation will compact the snow and therefore reduce the depth of snow depth, but consolidation does not affect the equivalent water content in the snow. The water content is set once the snow accumulates on the ground, it is what it is. The water content of the snow can only change by getting more precipitation or by melting enough to cause runoff. The snow blanket sensors on the internet can be misleading, especially as to depth. But in your example, since the water content increased, it indicates more precip occurred during the time frame you looked at. Since the depth decreased, the precip was probably rain, which helped consolidate the snow pack. Whether or not it turned to fluffy slush or icy crust depends on the local conditions (direct sun, evening temps etc).

                      The daily temp cycle in the Sierra's typically goes above and below freezing most days, which increases consolidation leading to "Sierra Cement." During the cold winter, the melting doesn't actually runoff, it just refreezes deeper in the snow. As the days warm up and get much longer than the nights, melting gets vigorous enough to start running off from the pack along the ground and increases rapidly as the air temps rise.

                      Most hikers are generally more concerned about snow coverage moreso than water content, or even depth. By spring hiking season, it will usually be well consolidated Sierra Cement - firm in the morning, softening in the afternoon, especially in the sun. It really doesn't matter how much water is in the snow you are walking on. If it's more than a foot deep, than it might as well be 20 ft deep, you can only sink so much. The question is how much of the trail has snow - and the snow depth data is better to gauge that. There is also satellite data to help assess general conditions.

                      Lastly, the depth of a creek or river varies throughout the day, depending on the path that the water takes on it's way down from the center of the snowpack (high on the mountain) to where you are crossing. As Ned wrote, creek stage (depth) is typically low in the early morning, but the lowest depth of the day can occur later in the day. It can be surprising in some places. The end of the day and early evening is typically the deepest, with maximum afternoon melt over and some time available for the water to arrive.

                      If I sound like a know-it-all, I apologize. I'm a professional in the water resources business, but I still might write something misleading.

                      --- In johnmuirtrail@yahoogroups.com, "Chris" <crhall41@...> wrote:
                      >
                      > I was checking out snow information on the CDEC web site and am somewhat unsure if my interpretation of the data is correct. For example the Bishop Pass site (BSH) shows that snow depth has dropped from 14 inches since March 25th (from 34" to 20") yet the snow water content has increased from 14.20" to 16.40". My interpretation is that warm weather has turned soft fluffy snow into compacted slushy snow.
                      >
                      > Mr Ditti/Others - can you confirm?
                      >
                      > thanks, Chris
                      >
                    • Chris
                      Richard, John Ditti responded to me via email and confirmed your suspicion. The SawmIll site is not Sawmill pass rather is actually located north and
                      Message 11 of 14 , Apr 25, 2013
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                        Richard,
                        John Ditti responded to me via email and confirmed your suspicion. The SawmIll site is not Sawmill pass rather is actually located north and downslope of Bishop Pass. It is at 10,200 ft elevation but is on the dryer east side of Sierra Nevada range thus the lack of snow. John also mentioned that the snow depth measurements are to be believed more than the water content measurements (as provided by the remote sensors).

                        Chris

                        --- In johnmuirtrail@yahoogroups.com, richard long <rcarllong@...> wrote:
                        >
                        > Interesting that the SWM sensor elevation is stated as 10,200' on the site. Sawmill Pass is about 11,400'. I don't recall seeing the sensor while I was there, but I always assumed it was closer to the lake, which is about 10000'. Please pass on the info if you get there this year and see the sensor, I like that area, and keep an eye on that reading.  In regards to the original question about crampons, if you are going in a couple of months, I believe it is highly unlikely that you would need crampons this year, unless there are some late storms. The last 500' before the pass narrows and has more shade, and  tends to hold some snow, but I doubt there will be much if any there in late June  this year. But that is just my opinion.
                        >
                        > Richard Long
                        >
                      • k2poohtri
                        Hello Ned, I will be highly interested in your findings as I m planning on starting my SOBO at Tuoloumne on May, 31 (I know, the area your in is about 2 weeks
                        Message 12 of 14 , Apr 29, 2013
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                          Hello Ned, I will be highly interested in your findings as I'm planning on starting my SOBO at Tuoloumne on May, 31 (I know, the area your in is about 2 weeks out from when I start but any knowledge will help). I know it's a low snow year, but there's still snow and the still snow melt, hence high water flow.

                          If you could please email me the trail conditions I would greatly appreciate it. k2pooh15@...

                          Thanks,
                          Korina

                          --- In johnmuirtrail@yahoogroups.com, <ned@...> wrote:
                          >
                          > Hey, just to add...
                          >
                          > Mountain Education will be on the JMT between Crabtree and Kearsarge May 13th to the 16th. We will let everyone know what the on-trail conditions are like when we get back!
                          >
                          >
                          > Ned Tibbits, Director
                          > Mountain Education
                          > www.mountaineducation.org
                          >
                          > From: richard long
                          > Sent: Thursday, April 25, 2013 9:27 AM
                          > To: johnmuirtrail@yahoogroups.com
                          > Subject: [John Muir Trail] Re: Snow water content vs depth
                          >
                          >
                          > Interesting that the SWM sensor elevation is stated as 10,200' on the site. Sawmill Pass is about 11,400'. I don't recall seeing the sensor while I was there, but I always assumed it was closer to the lake, which is about 10000'. Please pass on the info if you get there this year and see the sensor, I like that area, and keep an eye on that reading. In regards to the original question about crampons, if you are going in a couple of months, I believe it is highly unlikely that you would need crampons this year, unless there are some late storms. The last 500' before the pass narrows and has more shade, and tends to hold some snow, but I doubt there will be much if any there in late June this year. But that is just my opinion.
                          >
                          > Richard Long
                          >
                        • Ned Tibbits
                          No problems, Korina, but would you email me again after I get back from our SAC trip to remind me of your need? Since we’ll be leaving in a week after the
                          Message 13 of 14 , Apr 29, 2013
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                            No problems, Korina, but would you email me again after I get back from our SAC trip to remind me of your need? Since we’ll be leaving in a week after the SAC to do a one-week SIC, things get a bit busy in the turn-around!
                             
                             
                            Ned Tibbits, Director
                            Mountain Education
                            www.mountaineducation.org
                             
                            From: k2poohtri
                            Sent: Monday, April 29, 2013 1:22 PM
                            Subject: [John Muir Trail] Re: Snow water content vs depth
                             
                             


                            Hello Ned, I will be highly interested in your findings as I'm planning on starting my SOBO at Tuoloumne on May, 31 (I know, the area your in is about 2 weeks out from when I start but any knowledge will help). I know it's a low snow year, but there's still snow and the still snow melt, hence high water flow.

                            If you could please email me the trail conditions I would greatly appreciate it. mailto:k2pooh15%40gmail.com

                            Thanks,
                            Korina

                            --- In mailto:johnmuirtrail%40yahoogroups.com, <ned@...> wrote:

                            >
                            > Hey, just to add...
                            >
                            >
                            Mountain Education will be on the JMT between Crabtree and Kearsarge May 13th to the 16th. We will let everyone know what the on-trail conditions are like when we get back!
                            >
                            >
                            > Ned Tibbits, Director
                            > Mountain
                            Education
                            > www.mountaineducation.org
                            >
                            > From: richard long
                            > Sent: Thursday, April 25, 2013 9:27 AM
                            > To:
                            href="mailto:johnmuirtrail%40yahoogroups.com">mailto:johnmuirtrail%40yahoogroups.com
                            > Subject: [John Muir Trail] Re: Snow water content vs depth
                            >
                            >
                            > Interesting that the SWM sensor elevation is stated as 10,200'
                            on the site. Sawmill Pass is about 11,400'. I don't recall seeing the sensor while I was there, but I always assumed it was closer to the lake, which is about 10000'. Please pass on the info if you get there this year and see the sensor, I like that area, and keep an eye on that reading. In regards to the original question about crampons, if you are going in a couple of months, I believe it is highly unlikely that you would need crampons this year, unless there are some late storms. The last 500' before the pass narrows and has more shade, and tends to hold some snow, but I doubt there will be much if any there in late June this year. But that is just my opinion.
                            >
                            > Richard
                            Long
                            >

                          • K2pooh15
                            Hello Ned, absolutely. Enjoy the trips and good luck with the short turn-around. :-) Korina Sent from my iPad ... Hello Ned, absolutely. Enjoy the trips and
                            Message 14 of 14 , Apr 29, 2013
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                              Hello Ned, absolutely. Enjoy the trips and good luck with the short turn-around. :-)

                              Korina
                              Sent from my iPad

                              On Apr 29, 2013, at 4:12 PM, "Ned Tibbits" <ned@...> wrote:

                               

                              No problems, Korina, but would you email me again after I get back from our SAC trip to remind me of your need? Since we’ll be leaving in a week after the SAC to do a one-week SIC, things get a bit busy in the turn-around!
                               
                               
                              Ned Tibbits, Director
                              Mountain Education
                              www.mountaineducation.org
                               
                              From: k2poohtri
                              Sent: Monday, April 29, 2013 1:22 PM
                              Subject: [John Muir Trail] Re: Snow water content vs depth
                               
                               


                              Hello Ned, I will be highly interested in your findings as I'm planning on starting my SOBO at Tuoloumne on May, 31 (I know, the area your in is about 2 weeks out from when I start but any knowledge will help). I know it's a low snow year, but there's still snow and the still snow melt, hence high water flow.

                              If you could please email me the trail conditions I would greatly appreciate it. mailto:k2pooh15%40gmail.com

                              Thanks,
                              Korina

                              --- In mailto:johnmuirtrail%40yahoogroups.com, <ned@...> wrote:
                              >
                              > Hey, just to add...
                              >
                              > Mountain Education will be on the JMT between Crabtree and Kearsarge May 13th to the 16th. We will let everyone know what the on-trail conditions are like when we get back!
                              >
                              >
                              > Ned Tibbits, Director
                              > Mountain Education
                              > www.mountaineducation.org
                              >
                              > From: richard long
                              > Sent: Thursday, April 25, 2013 9:27 AM
                              > To: mailto:johnmuirtrail%40yahoogroups.com
                              > Subject: [John Muir Trail] Re: Snow water content vs depth
                              >
                              >
                              > Interesting that the SWM sensor elevation is stated as 10,200' on the site. Sawmill Pass is about 11,400'. I don't recall seeing the sensor while I was there, but I always assumed it was closer to the lake, which is about 10000'. Please pass on the info if you get there this year and see the sensor, I like that area, and keep an eye on that reading. In regards to the original question about crampons, if you are going in a couple of months, I believe it is highly unlikely that you would need crampons this year, unless there are some late storms. The last 500' before the pass narrows and has more shade, and tends to hold some snow, but I doubt there will be much if any there in late June this year. But that is just my opinion.
                              >
                              > Richard Long
                              >

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