Folks, this one may be a near total miss, unless you ski far eastern Maine, but don't worry, it will still rain a bunch and be windy regardless... There was a lot of trepidation in Storm Update #1, but at 48 hours out we had to go with the most likely scenario and fully forecast it, but that scenario now has virtually no chance of confirming and this "storm" is effectively canceled. It is now only a light event for snow, though the wind will cause some notable issues both Friday and Saturday.
The snow from this storm won't appear until the the surface low tracks sufficiently north for the trough to phase with it. The more to the east the low tracks and of course the slower it progresses north, the longer it takes for the change to snow to happen and that pushes the snow further east. Tolerances are pretty tight so we can see big shifts to the snow with smaller shifts in the track of the low.
Let's look at the NAM3K from the last 4 runs at 8AM through the 6z run this morning. Pay attention to the low's location in each one. The last frame is from this morning's run and it shows virtually no snow for ski country! That run has the low further south and further east than the others.
Here's why I think this last run isn't a fluke. The GFS and ECMWF ensembles have shown movement to the east in the last 24 hours despite the NAM3K and other mesoscale models showing snow as far west as the edge of VT yesterday evening. The last run of the NAM3K is now a pretty close match for the GFS in fact and that right there is the icing on my cake as far as this storm goes.
The GFS and ECMWF head-faked this earlier, at least in the ensembles, but they started to correct before the NAM3K, NAM12K, FV3, and HRRR mesoscale models did. All of those mesoscale models are NOAA models and they get fed data from the same sources and have some similarities that can cause similar behaviors at times in how storms are modeled. So it makes sense that we could see all of the mesoscale models shift west while the medium-range models shifted east for a period of time as they aren't all perfectly independent of each other.
So what does the snow look like? Well, it presently doesn't look huntable I'm afraid.
It does however look like the only open ski area on Friday that will be rainy after open will be Pleasant Mountain (if they open Friday). Many in NH and ME though will be quite soggy, and there will be some snow on parts of the Whites and Longfellows after open instead of rain. There will also be wind issues Friday and Saturday, and those will be covered below the paywall.
I will update again this evening in a subscriber alert if there is a notable enough shift to affect some ski areas, but I do not expect notable changes with the wind modeling from here. A small shift could bring enough snow to matter for a few mountains, but chances of a deep powder day are generally very slim. We are pulling however for Big Moose to get enough snow to reopen and they are certainly far enough east for there to be a chance, and upper terrain at Sugarloaf and Saddleback are next on the list for the possibility of a meaningful upgrade but with the wind in that area it may be of little consequence.
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
