Killington Snow Report, Pre-Dumpage Summary
H 17° / L 6°
January 18 Update From Braatencast: Scroll down for older models.
Significant Snowstorm To Bury the Green Mountains This Weekend
The models continue to point to a significant snowstorm the Greens and while there are still some small details to work out, the consistency of the model guidance at this point is hard to ignore. It’s actually very impressive that this was modeled over a week out and despite some slight shifts here or there, it has largely held serve. If this works out in the end, it very well may be one of the best modeled storms I’ve seen in years.
This storm will be fast moving and quick hitting, with snow breaking out across VT late Saturday evening and becoming moderate to heavy snow overnight through Sunday morning. The models are speeding up the storm system, so most of the accumulating snow could be out of the area by late Sunday afternoon. Overall, we are looking at a quick 12-18 hour punch of snow that should drop a general 10-18″ of dry snow across the state with some local variance due to banding. Chances for mixing with sleet in S.VT seem to be quite diminished.
Normally with a storm having such sort residence time in our area wouldn’t have me forecasting amounts this high, but rich Gulf of Mexico moisture is going to have a battle royale over New England with a very cold arctic air mass. As the storm system tracks from the Ohio Valley to the southern New England coastline, strong southerly winds aloft will lift this rich moist air up and over the cold dome. This should produce a fluffy snow and for this forecast I went with snow ratios around 13-15:1.
Right now the southern stream energy is crossing the western United States and is becoming well sampled by the weather models. The remaining questions surround Arctic stream energy in northern Canada that still is in a data-sparse region. Certain models like the NAM have been tracking the storm further south over the past few runs because it is flatter with this energy, not letting it dig south like the ECMWF. The flatter that northern wave is, the less phasing and downstream pumping of heights, causing a flatter solution off the East Coast. This piece will need to be monitored.
While that arctic energy could cause a slightly further south track, I also think there could be a near-term tick north with the track in the final 12-24 hours once the Gulf of Mexico opens up for business. Often times with these, strong convection down south will release copious amounts of latent heat into the atmosphere and that can serve to pump the ridge a bit more ahead of the system. The models have a hard time handling that convection and that can often result in a brief near-term tick north with the surface low in a moist dynamic situation like this.
Overall, I’m going with a blend that would include 0.6″ (far NW VT) to 1.5″ (SVT) across the state though most locations will likely fall into a 0.8-1.3″ water range. Applying 13-15:1 ratios to that yields the shown snowfall. Now, this water may be a bit less than some model guidance but I still think with an open wave at the mid-levels preventing good easterly moisture transport that QPF amounts could end up slightly below current model values.
The other caveat will be mid-level banding as the models are showing good 700-850mb frontogenic forcing between the warm air coming in from the south and arctic air to the north. That battle zone looks to run from the southern Adirondacks through Killington area and into central NH/ME. That’s where we could see localized rates of 2-3″/hr and someone could rack up a lot of snow in a short period of time as that stronger banding punches the snow growth zone. Very fluffy snow can stack awfully quickly in those situations. I may need to amend the location of that band as the near term guidance continues to fine tune the location. Some models, like the ECMWF lift that band further north into C/N VT but climatology tells me it often sets up further south in VT in lows that track along the southern New England coastline.
After snow tapers off later Sunday afternoon, we’ll see off and on snow showers in the mountains into Monday with maybe another inch or two of accumulation but you won’t be able to find it. The winds are going to get fierce behind this storm on Sunday night and Monday with brutally cold temperatures. Mountain temperatures on Monday won’t sniff zero degrees and serious wind chills will be present in the upper mountain elevations. Dress warmly if planning to enjoy the powder and exercise patience with Lift Ops teams as those winds on Monday will likely be problematic.
Enjoy the storm and I’ll update as I feel is necessary.
As I left for work this morning my thermometer read 4 Degrees Fahrenheit. Yes, that’s cold- but after last seasons -20 everything feels warm. That being said, everyone has been chattering about this weekends storm. Rental reservations are up, hotel bookings are up, and the local’s are brushing the dust off their powder sticks. But what is really supposed to happen this weekend? Like most weather predictions it’s incredibly hard to predict storms like this. The fact of the matter is that we’ll see some snow. It could be 8″ it could be 18″ but it will be some sort of a powder day. So what are should we expect? I again reference Scott Braaten, Stowe Snow Report, and Weather Pattern Geek. Scott’s Braatencast on Facebook is a great reference for winter weather predictions.
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.
Written January 15, 2019
January 16th Update (Scott Braaten):
Decent shift south last night in the model Ensembles, better news for SVT/Berkshires/SNH. Still great snows up here though. The pressing cold from the NW is trying to shunt it south and east. It’ll be a battle…
If you don’t make it up for MLK Weekend, long term forecasts look good too. So the snow will be sticking around for a while. Just remember to layer up and be safe!
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