Friday, November 21, 2014
We have a bad habit of making a big deal out of the white stuff in Seattle, and it seems to get worse with each passing ‘blizzard.’ It’s all too predictable; the chains on buses strike sparks with the ground as the snow that was seemingly ‘promised’ by the forecasters never came, schools close due to uncertain snow forecasts (this actually happened in 2008; Seattle Public Schools had a snow day when not a flake of snow fell), and suddenly, snow is the only thing in the world that matters. The last thing is actually nice for a change, but the hysteria that commences in the city is downright laughable.
But my favorite part of the Seattle snow rush is how it gets hyped up by the media. I don’t know if it’s because the writing staff have decided that their ratings will go up if they are in ‘winter storm coverage’ days leading up to the event, or if the newscasters just have a competition to see who can more effectively convince the populace that a winter storm of cataclysmic proportions is heading our way. Here’s how things usually go down in the newsroom.
Anchorman: “People are scared, and they should be. Snowstorms in Seattle are not only deadly, but dangerous too. The upcoming storm could be the worst we’ve seen in many, many years.”
Anchorwoman: “Flakes were spotted up earlier at Capitol Hill, and although it looks sunny right now, experts say that millions, nay, trillions of additional flakes are on their way.”
Anchorman: “People all over Twitter have been talking about the impending storm. iLikeClams says “my pulse is quickening, I hope my increased metabolism doesn’t create extra heat to melt any snow coming our way,” while No_Umbrellas says “I hate snow, I hope it ends up being rain so I can run in it naked.” Lastly, SubaruGurl4Lyfe tweets “I can’t wait for the snow! With my Subaru, I’m more prepared than anybody else in Western Washington who doesn’t own a Subaru!” Clearly a variety of opinions out there with regards to the snow.”
Anchorwoman: “There certainly are! But while opinions are great, we want the facts. With that, let’s take it back to our weather center, where our weatherman, Voice Reason, is standing by. So, tell us Voice, how much extra firewood do we need to buy?”
Voice Reason (shaking nervously): “Well, the truth is, there could be snow, or there could not be snow. Most models haven’t been showing snow at all, but there is one that has been consistently showing three to six inches of snow over our area sometime tomorrow. It’s really hard to know.”
Anchorman: “Thank you for that, Mr. Reason. It truly sounds like we are in for a catastrophic event. Hang in there folks, and button down the hatches. And don’t die.”
In Buffalo, that last sentence would actually hold true.
Buffalo and suburbs to the south are now recovering from the most severe lake-effect snowstorm in memory. 13 people have died. Dozens of roofs have caved in. Parts of the region picked up over 80 inches this week, and even more incredibly, most of that snow fell in one day. A suburb to the south of Buffalo picked up 66 inches (5 1/2 feet) of snow on Tuesday. If you average that over 24 hours, you get an average rate of 2.75 inches per hour, which is hard for me to fathom. There were reportedly times where thundersnow occurred with rates exceeding 5 inches per hour, which is absolutely shocking. For those of you who prefer the metric system, that’s slightly over a centimeter of snow every 5 minutes.
Any unprecedented event begs the question: “how on earth did this happen?” Well, as I mentioned before, this snowstorm was of the “lake-effect” variety. But what is lake-effect snow? And how did we get a pattern so conducive to it in the first place?
|Bering Sea cyclone on November 8 at its peak intensity. Credit: NASA|
Well, do you remember that Bering Sea superstorm that formed out of the remnants of supertyphoon Nuri? That was also a storm of unprecedented strength; it was the strongest extratropical cyclone on record in the Pacific. But this storm did more than cause hurricane-force winds and 50-foot waves, it actually was responsible for pushing a tongue of cold, arctic air into the lower 48, giving the contiguous U.S. its first “polar vortex” of the 2014 winter season. In fact, take a look at what I said from this blog post two weeks ago.
“This storm is so big that it will actually force a pool of arctic air down into the states this week. Yup, that’s right. An early-November polar vortex. And you can bet that will be covered, both in the media and on this blog.
Excellent weather forecaster, or supernatural meteorological prophet? I’ll let the reader decide.
I actually explained how polar vortices work in my previous blog post, so if you are interested on the physics of those, just read that blog. But now that we’ve got all that straightened out, let’s define lake-effect snow.
Lake-effect snow is snow formed when cold, dry air flows over a relatively warm body of water, picking up moisture and creating clouds and snow downwind as a result. These bodies of water are generally lakes, but lake effect snow has been known to occur over inland seas such as the Caspian Sea, and sometimes it can even occur over the ocean if the winds are aligned correctly. In fact, sometimes Sequim will actually get “Strait-effect snow” when we get especially strong arctic outbreaks as air picks up moisture as it crosses the Strait of Juan de Fuca and runs into the northeast side of the Olympics, rising and creating snowfall as a a result. The bodies of water have to be quite large; your standard holding pond isn’t big enough to create any sort of snow. If it were, you can bet that kids all over the midwest would collaborate to build ponds upwind of the superintendent’s house.
|Lake-effect snow formation. Credit: NOAA Earth Sciences Laboratory.|
The air flowing over the lake obtains heat via two methods: sensible and latent heating. Sensible heating is the heating we are all familiar with; if you have a stove top above a column of air, it will warm the air above it. Latent heat, on the other hand, is a function of water. It takes energy to evaporate water from the lake, so when this water vapor turns back into its liquid phase (i.e. where the clouds form), the energy inherent in the water vapor is then re-released, warming the atmosphere.
These two processes combine to make strikingly beautiful “cloud streets” such as the ones shown in the satellite picture below, which was taken on Tuesday the 18th at the height of the lake-effect snow-storm. Notice how it is clear upwind of the lakes, yet clouds form as soon as the air flows over them. Additionally, the flow is nearly parallel to lakes Erie and Ontario, meaning that a ton of moisture was able to have been suctioned up by this cold air. This, combined with relatively warm temperatures due to the early-season nature of this event and an extremely persistent, stationary flow, was responsible for the historic snow amounts witnessed in Buffalo.
|Cloud streets over the Great Lakes on November 18, 2014. Source: NOAA|
Buffalo is forecast to experience springtime warmth over the next week. While this may seem welcome after such snowfall amounts, it’s actually the last thing they need, as the warm temperatures will quickly melt snow. Roofs have already collapsed due to the immense weight of the snow on top, and this melting make the snow more dense and compound the problem. With five feet of snow turning to water, you can definitely expect a lot of ponding and flooding in regions that were particularly hard hit.
I’ll leave you guys with some pictures of the snowmageddon to gawk at. Brace yourselves.
|I think it’s going to be a long day. Credit: Empire State College|
|And the Buffalo Bills actually thought they were going to play here this Sunday. Credit: Buffalo Bills|
|I don’t even know what these things are. The Spectrum – University of Buffalo’s Student Newspaper|
And of course…
|If you’ve ever wanted to build one of these guys, now’s the time.|