I'm not going to call this one a "Storm Update" although that's what it really is, it's just not the type of storm we're looking for with both r@!n and wind, and the back end snow looks like barely a booby prize. On the crap weather scale of 1 to 10 this one only scores a 5 and you can find dry weather and non-held lifts both days at dozens of ski areas.
This update is really an addendum to the Weekend Outlook that was published yesterday. I have better guidance for the timing of the r@!n, and also some wind holds to look forward to on Monday that will mostly correspond with the r@!n. As always we'll start out with the wide view to set this up, this time from the ECMWF covering all of Sunday and Monday.
We've had a pretty good December as things go and the holiday so far has offered above average amounts of terrain for this time of year and even natural terrain open at quite a few ski areas, though that terrain is primarily too thin to survive much of a challenge. As Northeasterners are certainly used to the ups and downs and we will soon get another up. It looks like some will recover by the following weekend with the next storm similar to what happened earlier in the month with potentially days of back end snow! I'll put out something on that system later today.
I'll go over the Precipitation Forecast and break down the the timing of the r@!n on both Sunday and Monday to help you plan or dodge, and then in the Wind Hold Forecast I'll cover the impacts that are expected Monday.
Precipitation Forecast
Snowfall Forecast
We'll start off with the updated snowfall map. The snow shield has continued to condense, and as always there will be greater variability on the northern and southern edges of notable snow where a shift of just 25 miles with a storm so tight can either double or halve the amount of snow at a given location.
literally no two models agree and the NAM3K notoriously wobbles all over the place from run to run and when you have a mixing situation no other model lays a hand on it for precipitation types. I feel pretty good about this forecast except for one thing, how fluffy the snow is (SWE ratios). If I'm expecting 10:1 and it comes in at 8:1, it's still the same amount of water, but it will fall short of my estimates. I have about 6" for instance forecasted at Sugarbush and 6" forecasted at Okemo, but Okemo should get about double the amount of water in that snow and the difference is how fluffy it is. Ratios are a major factor in forecasting snow and it is not an exact science. They're literally still studying how to best calculate this.
After yesterday's update NWS offices pulled much closer in line with my forecast after bumping some, but unfortunately some areas took a turn for the worse and the NWS is now also trimming and they are generally below my own forecast once again. Here's the 5AM update from the NWS.
We'll see who gets this one right I guess, but I feel pretty good about my forecast as it stands. NWS offices are in at least some cases treating this as an elevation storm, and they forecast accumulating snow, some of which will melt and settle after falling on bare ground, but I forecast for the top 2/3 of ski areas for what falls on top of snowpack. Those are two different types of treatment, but mixing those two different treatments together is pretty difficult and gives me an edge by only forecasting for ski areas. I also make other sorts of manual adjustments; call them judgement calls.
Wind Hold Forecast
We'll start off with the forecast map, then there will be a loop showing gusts from 8AM through 4PM and then there will be a discussion regarding timing and scope.
This is a bit better than what it looked like from longer-range, but part of this is due to the fact that wind will increase through the ski day and keep increasing beyond it, so we're going to miss some of the worst winds.
Here's the loop showing wind gusts on Wednesday by hour. Every ski area is different based on many factors. Some can tolerate up to 50 mph as modeled here, while at the other extreme some can only tolerate up to 30 mph, but only from certain directions. Generally in Northern New England the danger zone though starts at 40mph.
Timing and Driving Windows
Here's a timestamped simulated radar from the NAM3K showing 7AM today through 7PM on Monday. This run shifted much warmer in Southern New England but I'm not completely buying that. The pinks and purples are freezing rain and sleet I don't really expect any freezing rain issues at open ski areas though, and sleet skis just fine, but it stings without something protecting your face is all.
Do not take the totals literally as this model overestimates snowfall on higher peaks especially above 15F. Treat this like a ratio.
I don't expect any issues in NY and VT at open, though Jay Peak starts getting into the danger zone shortly thereafter. NH and ME are a different story. Wildcat, Sunday River, and Sugarloaf are borderline in danger at about open and it will grow.
Knowledge Is Powder!
-- Matt
