This post describes the Fairbanks melting season. Learn why how snow height already decreases when temperatures are still below the freezing point. Read what happens in stores, with the snow, in town, and the consequences for dressing when finally the daytime temperatures go above the freezing point.
- Snow in Interior Alaska and Its Impacts
- Weather Differs from Climatology
- Snow Vanishes Visibly in March without Snowmelt
- How Does Snow Height Drecrease without Melting?
- Snow Metamorphism Prior to Onset of Snow Melt
- Stores Switch Put Out Their Rubber Boots
- Meltwater Clogs the Drainage Systems
- Rubber Boots Are A Must-have
- The Snow Metamorphism and the Dirt
- Aftermath of the Fairbanks Melting Season to Remove the Waste
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Snow in Interior Alaska and Its Impacts
In winter, the Interior gets quite some snow. No wonder that in winter, the Steese Highway often is closed at Eagle Summit for some time. This closure cuts off the road access to Fairbanks to the people living north of this point. During that time, they depended on subsidence lifestyle, what they had in storage and supply flown in by small aircraft landing on skids.
In town (Fairbanks), the department of transportation works 24/7 to remove snow. Along the roads and streets the snow are man-high in some places. The DoT drives snow in trucks to places outside of the city limits. Out in college, where we live, the snow was about the height of the mailboxes. The big pile of snow that the snow plow piled up in our front yard is so high that one can barely see the driveway lights (see photo above). We even had to shovel a way to the tank as the pipe was totally hidden under the snow-pack.
Weather Differs from Climatology
The normal annual snowfall for the Fairbanks North Star Borough amounts 61.6 inches (156.464 cm). However, from a wildfire and hydrological point of view, it makes more sense to look at the water-year-to-date snowfall in the area. The water year starts October 1 and ends September 30 the following year. The dates are chosen with the idea that the soil is at its maximum moisture at that time a year. This water is assumed to be stored and available for the next vegetation season.
On March 19, 2017, the long-year normal water-year-to-date snowfall in the Fairbanks North Star Borough is 51.8 inches (131.572 cm). On that day, the area had already a water-year-to-date snowfall of 77.8 inches (197.612 cm) this year! This means 1.5 times the normal water-year-to-date snowfall!
In 2017, the average undisturbed snow-depth is 29 inches (73.66 cm) in the area. The maximum snow depth so far was reached on February 26 with 34.1 inches (86.614 cm).
Snow Vanishes Visibly in March without Snowmelt
No there was no snow-melt between February 26 and March 19. This March was particularly cold. It seemed like someone had glued the needle at -25.6F (-32oC) even late in the morning. Of course, it got warmer during the day, but still, one had to bundle up and wear some extra layers. This March took a good try at confirming the old 1959 Johnny Horton song “When it’s Springtime in Alaska, it’s Forty Below.” 😉
How Does Snow Height Drecrease without Melting?
The thickness of the snow-pack decreased by snow metamorphism. Some of it is related to settling due to gravity. Another part is due to water vapor transfer within the snow-pack. The saturation water vapor pressure over a concave surface is less than over a plain surface, which itself has a lower water vapor pressure at saturation than a convex surface. Thus, the sharp edges of snowflakes sublimate already at water vapor pressures that still allow water vapor to deposit on concave surfaces. Consequently, dendrite-like crystals morph into hexagonal plates and eventually, at the end of the snow season, into ice spheres of about two mm (~0.08 inches) in diameter. During this process the density of the snow increases for which its volume and hence depth decrease. Remember, density is mass per volume.
Snow Metamorphism Prior to Onset of Snow Melt
On days when the water vapor pressure is below the water vapor pressure of a concave surface, the thickness of the snow-pack decreases by sublimation of snow at the surface. This process, of course, increases the water vapor gradient within the snow-pack leading to water vapor fluxes, snow metamorphism in the snow-pack as well. Furthermore, water vapor is transferred to the atmosphere thereby increasing relative humidity. In cold calm nights, this process may lead to fog close to the snow surface. Looking at the above diagram, one sees that March’s relative humidity was low, which means sublimation of snow occurred.
Note that on climatological average, March is the driest month of the year in the Interior with respect to precipitation (see diagram above) and cloudiness. Thus, March provides the best chances to watch the aurora.
Stores Switch Put Out Their Rubber Boots
Stores put out their rubber boots for sale when the long-term weather forecast predicts above freezing temperatures. The gardening sections exchanged their display of snow blowers to lawn mowers despite green-up typically isn’t before mid May. In Alaska, greenup is like pushing a button. The first signs of spring even though temperatures were still in the negative double digits (less than -23.3oC)
Meltwater Clogs the Drainage Systems
When the temperatures finally are above the freezing point during daytime, snow-melt sets on. Since the drainage system is still at below freezing temperatures, the melt-water freezes upon flowing into the sinks. The results? The drainage system gets clogged with ice. Consequently, all further melt-water has no way to go. Huge puddles exist all over town. Of course, gutters have the same fate. Water drops from the roofs, sometimes building long icicles.
Streets and driveways that hadn’t been plowed after the last snow storm turn into a mix of snow and water. When they are dirt roads you have the perfect recipe for mud.
At night, temperatures go below freezing. Consequently, water freezes at the top of the puddles building areas of pure ice where the puddles are not deep. The water on wet streets freezes as well. You see little crystals reflecting the light of the beams of your head lights. It looks pretty, but the streets are worse than what you were used to during winter.
Rubber Boots Are A Must-have
Because of all the water, rubber boots are in order. However, they conduct heat very easily. Thus, your feet get cold in no time. People wear double sock and rubber boots with jeans and a light jacket during day time.
Alaskans who can afford it have It Xtratuf. These boots are insulated. Thus, they don’t have the problem to get into the boots with doubled socks. Some even come with steel toe cap. Of course, it must be the Legacy one. They are brown and about mid-calf height. Around the sole is a beige trim as well as around the opening. These boots are so It that brides even take their Xtratuf to their outdoor weddings.
Since the Alaska It rubber boots don’t come with a high heel, I don’t have a pair. You know I love to find statement heels shoes and scored a pair high-heel Hunter boots. I wear them with boot toppers during melting season. This means these boots get out for about a week each year.
The Snow Metamorphism and the Dirt
The piles of snow along the streets turn gray or even black from the dirt and gravel that remain in the snowpack when the water runs away.
I don’t like the melting season because it brings out all the dirt of winter. Not only gravel that was used to roughen the roads during winter or seeds and needles that fell off the trees. Once the snow goes away it gives sight to all the lost mittens, scarves, candy wraps, plastic shopping bags, trash bags fallen off from pickup trucks, and whatever people lost or disrespectfully threw away during winter.
Aftermath of the Fairbanks Melting Season to Remove the Waste
Typically, in May after the Fairbanks melting season, there is a clean-up day. On that weekend volunteers collect all the trash in yellow plastic packs. The DoT collects and transports the bags to the landfill. Wouldn’t it be so much nicer when one would bring the trash directly to where it should be?Did you know this about the Fairbanks melting season? Click To Tweet
Dingman, S.L. (2021) Physical Hydrology. 3rd edition. Prentice Hall.
Fröhlich,K., Mölders, N. (2002) Investigations on the impact of explicitly predicted snow metamorphism on the microclimate simulated by a meso-β/γ-scale non-hydrostatic model. Atmospheric Research, 62, 71-109, doi:10.1016/S0169-8095(2)900005-4.
Photos of me: G. Kramm
Photos of snow and diagrams: N. Mölders
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