I Melt With You

2018-01-16 16:37:26.000 – Ryan Knapp, Weather Observer/Staff Meteorologist


Last weekend we posted an image (posted below) to our social media about our recent melt-out and since then it has been making the rounds on various media pages and online groups. Skimming the comments and replying to various emails, messages, comments, I have come across three things that I feel need a bit more emphasis.
Snow melt comparisonSnow melt between Jan 10 and Jan 13, 2018
Issue 1: People blaming one cause for the melt-out like the warm temperatures or rainfall
Unfortunately it isn’t so clean cut as blaming a single factor for the meltout. When it comes to melting, those in the field of hydrology look at several factors including, but not limited to, solar radiation, albedo of the snow, sun angle, dirt present on/around the snowpack, age of the snow, air temperature, humidity of the air, condensation/evaporation/sublimation rates, water vapor present, water vapor pressure, the temperature of the snow, sensible and latent heat transfers, sensible and latent heat transfers under windy conditions, conduction of heat with the underlying surface, and density of the snowpack. All of these factors can then be plugged into long equations or models that can be used to examine rate of melting and its impacts on runoff, neighboring waterways, groundwater supplies, or loss to the atmosphere. So a lot of things factor into it, to say the least.
When looking at our melt-out in particular, something one might overlook is fog (we were in the fog through most of the melting cycle). As my coworker touched upon in an earlier blog post, as water vapor condenses and becomes a liquid, energy is released in the form of latent heat of condensation. The latent heat then results in the snowpack either melting or evaporating. If it evaporates, it feeds back into the moisture present in the fog to later condense and repeat. Add in the winds and a fresh supply of moist air continuously condensing over the snow and it winds up becoming a repetitive cycle. And then you have the warm rain falling on the snow adding even more energy and moisture content to the equation. And all this time you have all these various phase changes occuring and feeding off each other and eating away the snow. And this feeds into some of the other factors I mentioned previously like the temperature of the snow, the density of the pack over time, and how it might be affecting surfaces below the snow.
And that is another factor overlooked – what was happening below the snow packs? As you may have seen in person or in pictures, the summit and surrounding peaks have a lot of rocks. These rocks are very large and piled several deep on top of each other (hence our nickname of “The Rockpile”). During the winter, snow early in the season works down into this porous surface filling the gaps until things level and then the snow piles on top. As snow melts, it starts to work down into the gaps of the rocks eventually leading to flowing water below the snow surface. As gaps open up, this then allows wind and fog to start penetrating beneath the snowpack in the porous network of the rocks. This causes various phase changes below the snowpack resulting in the snow to be undermined. Eventually this then leads to the snowpack being eaten away not only from above but from below speeding up the melt out even further.
Hydrology is not my major so I am painting a picture with broad strokes, but hopefully you get the picture that when it comes to the “why” behind our recent melt, it is not a simple x = y type situation; there’s a whole lot going on and it might not be as simple as the snow melting in your backyard.
Issue 2: People stating along the lines of, “Oh look, there’s no more snow. Guess I don’t need traction”
FALSE! You absolutely should pack traction of some sort – Microspikes, Yaktrax, Crampons, etc. While you might not need them from start to finish on the various trails of the White Mountains, they should still be packed as there are plenty of areas that still require them. While the summit cone of Mt Washington is melted out, looking down and around on the various peaks and trails we can see – both with the naked eye and with a telephoto lens, I can firmly say there is plenty of snow and ice around. In fact, there is more snow/ice below and around us then here at the station. And what melted off from up here is now refrozen below us either in the form of ice or once waterlogged snow that froze as temperatures plunged. The snow/ice conditions at lower elevations is also backed by reviewing the various trail conditions, trail reports (here and here), online forums, and Facebook Groups as well as talking with various hikers. They all state or conclude that you should have added traction with you. So don’t leave them at home, throw them in your bag as you will be glad you did.
Issue 3: People commenting along the lines of, “Guess the (ski, sledding, ice climbing, etc) season’s over”
FALSE! As I previously stated, below and around us have more snow/ice than we do – so our little snowless peak doesn’t equate to the entirety of the state. This is confirmed not only visually but through checking with surrounding weather spotters and consulting the various snowfall maps available. Checking SkiNH’s conditions page, resorts are still operating with plenty of lifts/runs available. I went out Monday afternoon to photograph a few of the ski resorts that were visible in the gaps of undercast to show what we can see – all of them look perfectly skiable from up here (see images below). Looking at snowmobiling conditions page, conditions vary across the state but still plenty of trails and terrain to play on. And various hiking trail conditions (linked previously) show that there is still plenty of snow to hike on.
Keep in mind that astronomical winter isn’t even halfway over yet (that falls on February 2nd). So there is still plenty of winter left. Was this a setback? You betcha! But I wouldn’t call winter over quite yet and I am being optimistic that it will turn around as I have seen it do here and elsewhere before. Winter 2014/2015 for Boston comes to mind. There was a point in January of that season where parts of Texas (like Amarillo) had received more seasonal snowfall than the Boston had over the same period. But then the snow-flood gates opened at the end of January and it dumped and dumped and dumped. I am not saying that will happen here, but it does show how things can still turn around in the second half of winter. Or if weather isn’t your thing, it would be the equivalent of walking away before the conclusion of the second quarter of Super Bowl LI and saying, “Well, Falcons won this one.” So, let’s let winter play out a bit more before we throw in the towel and draw conclusions.
Bretton Woods from Mt Washington summit 15 Jan 2018Bretton Woods on 15 Jan 2018
Wildcat from Mt Washington summitWildcat on 15 Jan 2018
Cranmore from Mt Washington summitCranmore on 15 Jan 2018
Attitash from Mt Washington summitAttitash on 15 Jan 2018
Loon Mountain from Mt Washington summitLoon Mountain on 15 Jan 2018


Ryan Knapp, Weather Observer/Staff Meteorologist

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