ORH_wxman

There was a pretty localized event in February 2015 in Boston I recall. I think it was maybe feb 11th or 12th. There was like an IVT with a streamer coming in off Boston Harbor. I rode the train into work that day...back then my office was on the seaport pretty close to Logan. There was sun shining in back bay and Fenway area, by the time I got to south station is was snowing steadily but pretty light. Prob like 3 mile vis. By the time I got to the seaport east of south station there was these perfect LES dendrites falling with like 1 mile vis. I think we ended up with 2 or 2.5” in about 4 hours there while even just north at Logan had about 1.5 and then back west around Fenway they had just a dusting. It was so weird. I think parts just south of where I was near Hull had at least 3”+ of pure 30 to 1 blower powder.

That clipper would have some real legs if we didn't have this offshore storm passing us tonight/early tomorrow. Kind of funny, that storm would have probably hit us if it weren't for Satruday's system, and now it's going to cause the clipper potential to be diminished. Wave-spacing 101. Still, if that vortmax is potent enough, we could see some decent snow showers.

Wow nice. Watatic still has a lot of very skiable trails visible on it. It's amazing how long they have lasted considering it hasn't been open in over 30 years.

Here is the look by day 8 on the EPS....even though the OP wasn't really interested in producing anything exciting, this ensemble look shows potential. You still have the block N of AK and a lot of cold loading into S Canada, so any disturbance coming out of the middle of the country should be watched....this is why I was thinking somewhere in that Dec 16-19 or Dec 15-20 range could be worthy of a threat. It seems there is a window of synoptic favorability there.

Fwiw, and it's not very much, but we could see a lot of snow showers around Wednesday afternoon/evening. That's a decent little shortwave that dives in from the lakes. Prob plenty of upslope posts from powderfreak, alex and phin which should get the juices flowing by the SNE posters. But even down here, there could be some snow showers. There's a little bit of a windexy sounding with TTs approaching 50, but we're lacking LL moisture to really get excited about much else other than flurries with some embedded snow showers mixed in....up in the orographic spots of NNE, it's a different story.

This is a really messy map below (96 hours on EPS and 120 hours respectively)...to agree with your point. I don't think we can write off even the weekend event as a total lost cause. Particularly for NNE. We'd need more help in SNE for obvious reasons, but you can see what is going on there....a block in the WPO region (building and rolling over into the EPO domain) with a pretty soft AO/NAO....almost a "ridge bridge" forming there. You also have split flow out west. Add it all up, and that's the type of look where you can get corrections to colder outcomes. If not enough in time to help this weekend, perhaps the event behind that one.

We saw this in Dec 2008....here is the 5-6 day forecast for 12/19/08...the last image was how it turned out. Doesn't alays work out like that of course. That was 12 years ago....but even now the models have a lot of toruble in Nina with blocking up near AK.

Almost looks like 12/16/07 with that high location. Maybe shove it southeast just a shade.

I dunno...the max snowfall for the eastern zones in MA was really like 4-8pm on the model guidance....I agree the models did seem to go on too long after that, but the core of the best stuff was forecasted mostly late afternoon and early evening....which from a rate standpoint, largely verified. Maybe we're having two different discussions here..... 1. Did downsloping affect things later on? Yes. The precip after 7-8pm did not really match model guidance which suggested perhaps 2-3 more inches for E MA even at modest 7 or 8 to 1 rations. 2. Was downsloping the main reason for the lack of snowfall accumulation between 4-7pm? No (IMHO). I think our cross sections are explaining that better with the "perfect storm" of toxic brew....as Chris said, the lower elevations needed either slightly more LL cold or for dendrites to overcome the lack thereof, and we couldn't get either. Places like BED and LWM were getting heavy white rain...slamming plenty of precip into the buckets, but just not accumulating it on the ground.

I think the lift location is more important than “shadowing” which implies a drying out of the atmosphere. The precipitation was pretty prolific still looking at LWM on the upper 495 belt pretty quickly. I see hourly bucket tips of 0.16, 0.18, 0.12 after 5pm. That is heavy stuff. They just couldn’t accumulate it. It was white rain.

It's pretty clear that Canada will have some cold....at least for most of the Dec 12-20 period. Less clear beyond that. Now if we can get some timing, then we'll certainly have a chance or two.

Yeah Jefferson is still way better than places like Lancaster and Whitefield, but they are on the "same side" of the terrain as them, so that's definitely why there is a notable difference between them and Randolph which is on the other side of those key terrain features. The snowfall seems to really increase once you get into the "curve to the east" part of Rt 2 about a couple miles east of downtown Jefferson.

It's not a great pattern but watch that block N of AK....that can sometimes wreak havoc on the modeling as arctic shortwaves dive down east of it and perhaps give us some colder solutions than guidance currently suggests. We've seen that plenty of times in the past....it's basically the opposite mechanism of how when there is a death vortex over AK, we often see things trend warmer the closer to verification we get. You can see the progression of the block N of AK...it eventually retrogrades and weakens, but it is something to watch because that type of block usually biases results a bit colder. Also watch the eastern NAO stuff as well.

The old Jefferson coops and the NORHC snow map archives showed a clear decrease of snowfall into Jefferson vs Randolph on the other side of Pilot/Pliny range.NE wind def downslopes them and they don't have the CAD capacity that further east does.

Probably the ugliest above average pack duration winter of all time up there. I wonder how many days it was a crusty 2 or 3”.

The only winter in the mid/late 1970s that came close where you were is prob 76-77 but even that winter had most of December with no pack after the late November snow was torched away by a cutter. Ditto ‘77-78 but even less close.

We actually have a pretty stout EPO ridge this week/weekend but we get a cutter with it (most likely). Shows the risk of EPO ridges at times. Theres probably a window behind the cutter to get something.

Yeah it should help at least keep some cold nearby. It’s going to be above average for that period but that look still gives a chance for something unlike the more classic Death Star pattern.

Looks a bit like the last 10 days of dec 2007 or so...there just enough WPO to push the lower heights further south into Canada and the western US. That was an above normal period for us but it did have some threats and a couple advisory events.

This crap was like slime and then froze overnight. Back in holliston we got about 4” of Italian ice. But the piles make it look like double that because of the water content.

If you want to hone in on a narrower range, I feel like the best period for us is probably like 12/16-12/19. That’s when there’s some cold established nearby (or hopefully over us) and could work with an imperfect synoptic setup.

They didn’t. Unless maybe you live in Norfolk.

Yeah you’re left with like these -5C needles falling into that deep 32-33F layer. Not a good combo for efficient accumulation is an understatement.

The lift was lowering throughout the event over E MA. There was prob more DGZ lift during the initial changeover than later on...maybe Chris or someone has easier access to the cross sections than I do at the moment, but I’m pretty sure i recall seeing the lift a bit deeper earlier in the event. Usually once you flip over to snow, keeping excellent DGZ isn’t a huge deal because your in the CCB and often advecting cold air into the system...but this was a unique system in which we were not so the issue ended up more glaring than it usually would be.

And the best zone that had decent lift in the DGZ was further west over ORH county into adjacent S NH...so they had the double advantage of better DGZ lift plus some elevation. It’s probably why you saw like 9-12 inches of snow there while Ray in Methuen was struggling to get 2”. You hardly ever see that type of gradient unless he was mostly raining which wasn’t the case.