Terpeast

Commanders are so back

Still nothing. Don’t think it’ll happen. Rt 15 looks like a wall

Nothing yet in Ashburn, hoping this band pushes east of 15

12z Euro starting to latch onto a 500mb s/w on 12/7-8. Decent vort pass over us. Nothing on the surface yet, but it's a change from the last run. After that, the 12/11 system cuts to the lakes.

Hard to say. Some members still show a dec 8 wave, at which time we have the cold air to support snow. But how strong it is, and whether it’s even going to play out or get swallowed up by stronger energy out west, is still TBD. Unfortunately it’s been trending the wrong way for several days now. The stronger system could potentially be a Midwest low, with coastal redevelopment. Best to hope for with that system is we have enough cold air damming to keep up the potential for a front end thump before changeover. Not loving the ice storm scenario, though.

I noticed the GFS ensembles trended weaker with the SW energy and this is becoming a wave almost purely driven by the NS. New run: Old run from 3 days ago:

Yep. It seems the models, esp the GFS, are completely lost as to handling the dec 8-11 system (we can’t even nail it down to a calendar day). Until we see multiple models converging onto a similar solution, nothing is off the table.

Either way, low confidence. It’s not going to be as clear cut as we thought it would be even a month ago when it looked like another record warm winter through and through. It’s looking more like there will be a couple of surprise curveballs along the way. Not saying it’ll be a BN winter/AN snowfall in the east, I’m sticking with my AN temps and BN snow outlook, but probably not as bad as we thought.

I think that is a low confidence outlook given that the AAM’s weakening is forecast to only be temporary. Although the Dec 10 “moderation” coincides with the AAM going neutral, the CFS is projecting the +AAM to restrengthen after mid-Dec.

it may be speeding up just a little… IIRC previous runs showed it still in 5 until the 11th or so

I can see that playing out if the MJO goes into 7-8-1 and the AAM stays positive. Even a +1 C won’t be prohibitive for snowfall in the MA.

They could be trying to revert to a standard La Nina pattern, except they keep maintaining -EPO. But two weeks ago, they were depicting a torch around this time and that was a huge miss. Maybe it’s just a one-off, but with the continued +AAM and the MJO going into 7 and 8 later this month into January makes me think otherwise. The new Cansips seems to have shifted in that direction, too.

All ensemble models show cold air reloading in W Canada while maintaining -EPO at the end of their runs, so any mid-month moderation may be short lived (a week, maybe 2).

All ensembles show cold air reloading in W Canada while maintaining -EPO at the end of their runs, so any moderation may be short lived (a week, maybe 2) Still having trouble resolving the dec 8-11 threat(s). Need another couple of days to converge on the most likely solution

20.3 for the low

21.6

Yeah that’s a chilly look. Flow is fast, though. +nao keeps things moving along, but that in combination with the -epo also “fixes” the PV on our side of the globe (as opposed to the other side)

26 and dropping fast

Don’t look now, but new Cansips now predict a NN DJF for our sub. Previous run was a torch. Source: Eric webb’s tweet Old runs from TT:

Yeah, even the ensembles are shifting. Too chaotic to get a good read on it.

Your contest numbers are slightly more bullish than my own…

Agree. More like U40s/L50s for the highs and lows around freezing or just below. Sometimes we can snow with that if well timed. End of GEFS run shows cold source developing even when we go mild. Wouldn’t take that long to get back into a colder pattern especially if it coincides with the MJO going into 7 and 8.

Only 36 for the high

To add to this, even if we go milder after 12/10, we still have a ridge over AK which should maintain our source of cold air. It's not as if the pac jet will ape and wipe out all cold air from the entire NA continent, like it did early last December and we had to wait 4-5 weeks until it finally reloaded.

I'm sticking with my guesses. No changes...