An active week of weather is on tap for the Green Mountains, with the hype already building for a big MLK Weekend snowstorm. Prior to that we have a few smaller systems to contend with and a near term concern for some light icing in the mountains of central and northern Vermont tonight. I’ll break this post down by event, with discussion regarding the potential storm on Sunday saved for the end.
Today saw some light freezing drizzle across the northern Greens due to moisture trapped under an inversion just above the surface. The thick stratus deck produced a mix of light snow and light freezing drizzle, but from all accounts there was no impact to the snow surfaces except visibility was an issue this morning from goggles freezing up from the mist. We should see those conditions persist tonight and tomorrow morning in the high terrain until an arctic cold front moves through tomorrow afternoon. A light glaze is possible overnight inside the clouds that will reside above 2,000ft.
Tomorrow afternoon a decent arctic cold front will swing through towards the end of the ski day. With good surface convergence along the front coupled with upslope flow into the northern Green Mountains, a quick 1-3″ of snow is expected in snow squalls from Sugarbush to Jay Peak. Isolated amounts up to 4″ are possible in the highest elevations where any squall may linger. Winds will increase behind the front and it will get very cold for Thursday. In fact, Thursday will be the day to wear everything you’ve got as temperatures will stay below zero above 3,000ft with wind chills approaching -40F at times.
Another weak storm system will approach us Thursday night, bringing with it southwest flow aloft and warmer temperatures for Friday. The energy aloft driving this system is quite weak and the system will be moisture starved, but a fluffy 1-4″ snowfall looks like a decent bet on Friday morning across most of Vermont. Any remaining light snow showers should taper off by early Friday afternoon, followed by another shot of arctic air to start the weekend.
Saturday of MLK Weekend will see increasing clouds and cold temperatures, with highs in the single digits in the base areas and below zero at the summits. If heading to the mountains for the holiday weekend, dress warmly. It is late in the day on Saturday when things start to get interesting.
Now, I’ve seen a lot of mentions of possible accumulations already for the weekend but it is still 5 days away. That is an eternity in weather model land. If some models are even struggling with Friday’s weak storm system, how are they going to know what Sunday will do?
In fact, most of the players on the field responsible for the potential storm are still located over data sparse regions of the Pacific Ocean and northern Canada. The models right now are making a lot of “assumptions” based on satellite data. In my opinion it won’t be until Thursday when we really get a good feel for what will happen. By that point the energy involved will finally be adequately sampled and the models will have a much clearer picture of how this will shake out.
When talking about data sampling, it means that by that point the weather systems responsible for our storm will now be over portions of North America (such as the United States), passing over airports, radar sites, weather balloon launches, and even getting passed through by hundreds of commercial aircraft. All of those things collect data which then is fed into the supercomputers that the weather models run off of. The more complete a picture the models can get of the atmosphere at initialization, the more accurate the outcome will be. Right now the pieces of the puzzle are still over data sparse regions, so the models are making assumptions on variables that can have huge downstream effects.
Basically the bottom line is, there is great uncertainty in the sensible weather outcomes at this lead time. What is known is that a good sized storm is likely to form in the lee side of the Rockies, but where it tracks is still very much up for grabs.
The attached graphic includes the three possible tracks that seem most likely at this time. The furthest south track would include heavier snows in the Catskills, Berkshires and southern New England, with lighter snows north. The currently modeled track wants to cut the low pressure system near the south coast of New England or even inland a bit through southern New England. That would produce heavy snows for the Green Mountains and would likely also include at least some mixed precipitation into southern VT. The furthest north track would produce a snow to sleet/freezing rain type event across most of Vermont as warm air aloft punches northward.
My gut instinct is telling me most of Vermont will remain all snow and it will only be a question of how much. Very cold arctic air pressing down from the northwest should be enough to force this storm to track east and not over us. I’ve seen some comments tossing around very large amounts of snow, but this system looks to stay progressive as an open wave in the mid-levels. That would make widespread amounts of heavy accumulations (say 10-12″+) quite difficult to achieve in a fast moving system. The system will have copious amounts of moisture from the Gulf of Mexico, but without a closed mid-level center moving underneath us, we wouldn’t get that easterly flow of moisture advection off the Atlantic. That should serve to keep expectations in check until this becomes clearer in a few days.
Like I stated earlier, I think by later Thursday we should have a pretty good idea of how this will pan out but there are still plenty of options on the table. In the end, snow seems more likely than not at this point in time and I’m cautiously optimistic that we can finally get a snow event to coincide with a holiday weekend on the slopes.