ORH_wxman

No pattern change to see here

Here's a good visual....you can see early on how there are still above normal heights in the south while we are BN..... Then you will note how late in the period at the end, the heights are below normal across all of the east including the southeast with the ridging pushed back toward western plains and rockies.

I think the velocity issue will probably be present early on in the blocking pattern because it is still fighting the SE ridge a little, but it seems to really relax after the first week of the pattern or so....at least it's implied by the models. We retro some of the ridging back toward the Rockies and that really loosens the gradient between Quebec and the SE US. We'll see if it plays out that way....but regardless, we'll still likely see threats either way....but if we're fishing for the Big Dog, we'd obviously want to see that relaxation in the south.

Yes we can see the posts.

That's a good thing in that it keeps us in the game when the PAC goes kind of ugly...then ideally, you'd have the PAC go more favorable as the block finally breaks down (ala January 2011 when kept the fun going all month into early Feb after the block broke down during the 1/12/11 event)

The flow does get a bit zonal on ensemble guidance for a few days but the biggest effect is out in the plains. We keep colder due to huge NAO block and the plains mini-ridge looks like it retrogrades back toward the Rockies after a few days. As long as we have that block, we’re fair game for something.

For your ‘hood, it was prob 1945. For northern part of SNE N of the pike, could be 1970. ORH is actually 1992 but that’s a bit deceptive since it’s almost all from that one storm.

Orientation of the block would have to change pretty dramatically to set up a semi-perma ridge over the east that links up with the NAO block. We get the eastern ridge temporarily as the block is just starting to set up shop, but it quickly goes away because that block is oriented from like Iceland back into Davis strait which isn’t the way to blow up an eastern ridge. It forces PV lobes underneath when it’s oriented like that. It’s possible the orientation changes but that’s pretty doubtful considering the consistency and cross-guidance agreement.

12/6-7 kind of looks like that. That’ll send many into a bit of a tirade I’m sure regardless of how good it looks going forward.

Here’s the progression. You can see the initial cold dump west…but those low heights get forced under the NAO block as it migrates eastward. When we have a +NAO, it often will just swing up into Baffin/Davis Strait and keep us in a perpetual ridge situation….but not here. Dec 5th Dec 8th Dec 12th:

I’m not really getting “PV into the western US while we stay warm” vibes from this look…but whatever urgent panic floats your boat is fine, just at least support it with something. The initial cold dumps west…no disputing that, but it doesn’t maintain that look.

Even in 2010, the pattern flipped around 12/5….but we then whiffed on a snow chance a day or two later and then we had a torching cutter on 12/12/10 within that favorable pattern. The retro storm on 12/21-22 was our first accumulating snow in the pattern and it was only a big deal on the Cape. Boxing Day finally happened a few days later.

Yes I know it would be. That’s why we’re posting it so that you can re-adjust your expectations. Sometimes we get a snow event right at the beginning of the pattern change, but sometimes we don’t and we have to wait a week-plus.

There’s a pretty reasonable chance we don’t get any snow events through 12/13. That’s like a week (maybe not even) into the pattern change. I’d be surprised though if we made it to 12/20 without one.

Some people should prob log off for about a week and then check back in. There’s very likely going to be no threat to track until at least that point.

Yep. If people want to quibble about the colder look being Dec 8-9th vs Dec 6-7th…ok that’s fine. Not sure why anyone would care about that difference 2 weeks out, but it certainly never looked like a cold pattern locked in by Dec 1-3. In fact, it’s looked quite mild during that period on like 90% of the runs in the last 7+ days.

When was the good pattern supposed to lock in Dec 1? That’s been in the crap period almost the entire time. There was a very brief couple runs over a week ago that sort of muted the mild pattern in the first few days of Dec but it quickly reverted back to mild. It’s been very consistent on post-Dec 5th.

Retro storm that crushed the Cape. They had over a foot in some spots there. It was an otherwise frustrating winter on the Cape but they got smoked in that one. It did snow like 2-3” though around BOS. We even had a couple inches back in ORH which gave us a White Christmas.

That was Jan 2015….but same point nonetheless.

Hard to say…rarer if you start 40 or 50 years ago as your baseline. There were a bunch of snowy Novembers in the 1980s…ironic considering the winters were mostly shit for snow. But really prior to the 1970s isn’t impressive. 2” or more Novembers in BOS by decade: 2010s: 1 2000s: 2 1990s: 2 1980s: 5 1970s: 3 1960s: 1 1950s: 1 1940s: 2 1930s: 3 1920s: 1 1910s: 1 1900s: 0

Late Dec 2010 to first half of Jan 2011 vibes. That doesn’t mean weenies should start expecting the same results because it’s not exactly the same and snowfall involves a lot of nuances anyway….but the large scale features are very similar.

Yeah i think roughly 12/7ish would be our first shot at anything significant. But there’s likely to be many more chances after that with that type of blocking present. I posted the 5 day mean h5 but even on the snapshot of the last panel, that blocking is going to town which would imply having favorable setups well into mid-month

I started posting on December in the December thread…November almost done and unlikely to see anything of significance the rest of the month

Model guidance continues to be consistent in showing the more interesting pattern after 12/5 Very good agreement between EPS and GEFS.

You must’ve had 6-8” in that one? Had 6” on winter hill. I remember driving up to Killington two days later and snow was still plastered to all the trees north of Sterling. All along rt 2 from Leominster through Athol was pasted.