Any compulsive weather addicts know how tricky it is to forecast weather for a region-most people say the forecasters are “wrong”. A better interpretation would probably be to say they aren’t accurate, and Vermont is a great example of why. The National Weather Service has various offices, and ours is in Burlington at the airport. They cover a large area, from Lake Placid to Montpelier, and from the Canadian Border to Killington. The only way to accurately forecast an area this large is to break it into regions. For example, our region is number 9, Western Addison, including the cities of Vergennes and Middlebury. And here lies the problem with forecasting, particularly in the winter. Middlebury campus is under the same forecast as Lake Champlain, and Vergennes shares the forecast with Brandon. It’s a huge geographical area, and one forecast for such a space is bound to lose accuracy across the region. Addison may get an 1″ of snow, low in the valley, while East Middlebury may be getting hammered with 6 times that, under the same forecast.

The Weather Underground has been taking the National Weather Service forecast, and re-packaging it on their website, along with access to some great radar maps, blogs, photos, etc. Recently, however, they’ve starting forecasting themselves, called Best Forecast, and what makes this different is the data, not only from all of the NWS weather stations, but all of the personal weather stations such as ours. Slate just wrote a great article explaining this. Suffice it to say that Best Forecast is now taking into account microclimates, so when pulling up a Middlebury forecast on the WU, we are getting a Middlebury campus forecast.

How accurate? We’ll find out tonight and tomorrow. The NWS is forecasting a dusting to 2″ of snow tonight, with an additional 3-5″ possible tomorrow before it changes to rain. Temperatures mid 20′s tonight, mid 30′s tomorrow. Best Forecast? Lows of 28 tonight, 50% chance of snow or rain, high of 45 tomorrow, snow than rain in the afternoon, snow accumulations of 1″ possible. I’m not placing bets on who is correct here, but the Best Forecast feels right to me. I’ll post an update when all is said and done.

UPDATE 4PM: The NWS issues forecasts at fairly regular times, 3 PM or so being fairly regular. Their update for the western addison zone has changed slightly, 2-4″ during the day tomorrow, changing to rain in the afternoon, back to snow Friday night with an additional 1-3″. Mid 30′s tomorrow, mid 20′s tomorrow night. Best Forecast has changed little-snow and rain tomorrow, accumulation 1″, chance of ice pellets, snow and rain friday night, only 60% chance, no accumulation mentioned.

UPDATE 12 NOON FRIDAY: The NWS has changed their forecast, as the storm seems to have slowed down from the west. No snow last night, and only light snow now at noon, not accumulating. So do we call this a win for Best Forecast? Both forecasts now are in line with each other for snowfall tonight, 4-6″, but Best Forecast is calling for temps today around 45, with the NWS saying mid 30′s, which it is now. I’d be surprised if temps rise today.

I was introduced to this my first winter at Middlebury, during the Valentine’s day storm of 2007. The roads were impassable- I’d tried with a friend in a four wheel drive truck, and we’d turned around and went back to the college to spend the night. This was no ordinary storm, but a a blizzard, so strong we couldn’t keep up with it, either by shovel, tractor, or plow. The most important work of the night remained, though, so we broke into teams of two or three, shovels and putty knives in hand, and trudged from building to building, closing doors.

A plumber told me Middlebury has 110 buildings. I asked him how many exterior doors were on campus, and got a look like I’d lost my mind. Fire codes dictate at least two per building, and some many, many more, so let’s say there is 500. Most of these buildings are heated centrally with steam, from the Service Building. The operators in there work wonders, 24/7, heating the entire campus. Ever had snow block your main door at your house, preventing it from closing? Even if you don’t notice immediately, I bet you quickly figure it out as the draft quickly goes through the house. Some storms seem block doors better than others. Now imagine if even a couple of doors on campus are like that. The magicians in the heating plant notice. Now imagine those storms where even 10% of the doors are stuck part way open. The steam can’t compete,alarms in the plant go off, and precious steam and heat literally goes out the door.

So we go out, putty knives in hand, cleaning door thresholds, making sure the door is re-sealed against the building. The knives scrape the snow from the threshold, and from the underside of the door. It builds up against the door frame as well. If you’re really unfortunate, or in the right storm, hot air from the building is melting the snow in the way, and it re-freezes to rock hard ice.

We’ll gladly do the shoveling, plowing, and salting. Save us some time, though, and close the door behind you. What, did you grow up in a barn? Snow stuck in the threshold? Grab a knife from the dining hall if you have to, I won’t tell Aunt Des.

Luther reports 11 snow events so far this year, a snow event being one all of facilities needs to respond to. An average winter contains 18 snow events in total. He also states 19 of the last 20 days in January has seen some snow, and 24 of the 31 days in December.

I never got around to posting this, but here’s a great satellite picture of the nor’easter that hit us on January 12. I’ve lost the name of the site it came from, but I remember it’s from the National Weather Service. We’re in a break from snow now, as the bottom seems to be dropping out of the thermometer. Some of the coldest arctic air we’ve seen in 2-3 years is plunging south, so stay warm.

The issue with snow and ice is always one of traction. Getting rid of most of the snow is relatively easy. Shovels, plows, snow blowers, brooms, even backpack blowers are all used, depending on conditions. The challenge in the winter is the last 1/4″ or so, the snow or ice remaining that doesn’t want to go anywhere. The problem is warmth, and the fact that the very first snow that falls on sidewalks or roads bonds to the surface, and can be very hard to scrape away and remove. This is what makes winter treacherous, and what makes walking and driving difficult.

In the past, Facilities Services has used sand, and a lot of it. Spread on top of this bonded snow/ice hard pack, the sand gives traction on top, making the walk or road a little less slippery. Most of the time. Sand comes with costs, though, some obvious, some not so much. Sand use in winter is linked to phosphorous loading in streams, sedimentation buildup in catch basins, retention ponds, and waterways, and even airborne pollution, as the cars and trucks driving across the sanded surface grind the particulates into finer particles and allow them to become airborne. But the worst part of sand? The carbon footprint, not only in spreading a heavy product, but repeated trips to refill, the continual scraping of the surface to try and remove the leftover hardpack repeated over days, and worst of all, the massive amount of work and fuel required in the spring to clean all the sand up. After all that work, there is still snow and ice left on the walk. The sand seems to disappear, moving off the hardpack to the edge, and the walks are slippery again.

The other solution to the ice problem is to get rid of it, frequently by melting it. In a bulk scale, this usually involves rock salt. Ever make homemade ice cream? Rock salt lower the freezing point of ice, so that it stays liquid at a colder temperature, allowing the milk to freeze. Applied to a road, the salt thaws the ice or snow hardpack, where it runs off as water, drying the road. This certainly has it’s problems too, not only in the carbon footprint to get salt across the country, but in effects both in water and soil of excessive salts. There are other ice melter products, from calcium chlorides to magnesium blends used on airport runways, but most bulk applications still rely on plain old salt.

Facilities wasn’t satisfied with sand, as anybody walking across our sidewalks in the past might attest to, but we weren’t sure about salt, not wanting to make an environmentally worse choice. (It’s neck and neck, actually, between sand and salt, if you actually take the time to weigh the pros and cons.) A couple of years ago we started using Ice Ban as a pretreatment. This liquid is the byproduct from food manufacturing (I believe our source is actually from beer), and sprayed on sidewalks and roads before a storm can prevent the dreaded bond from forming, allowing the snow to be completely removed. This is tricky, though, as conditions need to be perfect in order to apply, and this only seems to be about 2/3-3/4 of our snow events. Then we discovered magic.

Magic Salt is ordinary rock salt treated with ice ban, or an equiviant. This agricultural by-prodcut gets sprayed on the salt, turning it brown and giving it a somewhat funky smell. It makes the freezing point of water drop even lower, meaning less treated salt is needed to melt the equivalent amount of snow or ice. Some estimates claim 30-50% less. And much much less sand/salt mix, up to 3 times less. Less product=less carbon. And we’ve got cleaner sidewalks. This is our first year of trying Magic Salt, and so far we’re impressed. But don’t take my word for it, the proof is in the pictures.

Here’s a sidewalk treated conventionally with ordinary rock salt (not by the college). Yes, the sidewalk is clear, but note not only the chunks of excessive salt remaining, but the white residue of the salt on the walk. It’s very easy to over apply salt.

This is one of our walks, treated with Magic Salt. Very clear, but notice there is no excess salt on the surface, and no white buildup of salts on the sidewalk either.

One night this week it snowed on top of cleared sidewalks in the middle of the night, and night time temperatures were in the single digits. Temperatures this cold are below the effectiveness of straight salt, it just won’t melt the snow. The sidewalk above was treated with straight rock salt the day before, and you can see the bond that formed between the walk and the snow. There are footprints in the snow above. Compare it to the the picture below.

This sidewalk was treated with Magic Salt the day before, and, while it has received more foot traffic than the walk above, you can still see how there is no bond formed. Even walking on this sidewalk was more pleasent, and not as slippery as if the snow had bonded down. And with this type of surface we can…

Sweep the walk clear. A broom on one of our tractors came along and in no time at all discovered the bare surface again.