WxUSAF

Lol look at these closed 500mb shortwaves tracking south of us on the GFS and just a rotten airmass. Please Jesus let that continue once we get even some marginal airmass.

I think we get teased in the Jan 7-15 time period. Maybe something does work out then. It wouldn’t shock me. The difference between “great” winters or periods of winters and “fine” are usually whether we luck our way into some marginal events. By many numeric indices (AO, etc) we’re going to underperform this December. For the folks north of the Fall Line, it’s going to be a “fine” December. But could have been better. We’ll see what January offers.

We score a solid storm in late Jan. Then pattern relaxes for two weeks. Great pattern returns around V-day, but we get fringed while NYC on north gets 2’. 80F by March 5.

Ggem suggests some follow up energy rotating through next Tuesday. Para GFS hints at it also. Maybe something to watch also.

The overnight D10 EPS pretty clearly answers the “just high heights” or a true ridge in the NAO domain. It’s the later. And as Webb showed, the EPS is also lessening the torch temps underneath that block. Something to watch going forward. Still makes things needle threaders, but maybe a bit more give available for the Jan 7-15 timeframe?

With that big block and possible 50/50 lows, I think we’re going to have some close calls Jan 7-15. At least to the point we probably get teased a few times. But going to be needle threaders if anything. After the 15th, I think we get busy. If the advertised pattern comes to fruition, I think odds are definitely higher than normal for KU type events. Especially considering it’s a moderate Nina.

Just as an example, but 18z GFS is the sort of evolution through the first 2 weeks of January that we want to see. -NAO/-AO rocks starting in a few days, and then PNA/EPO ridging starts to build around D11. Then by the end of the run, you’ve got 850 temps below normal for much of the CONUS. Actually the pattern is barking for a big dog at 384...

The H5 looks on all guidance are excellent by mid January. But 850 and 2m temps are still mild at that point. Going to take a bit of time to get some cold air moving south, but that much improved Pac will do that eventually.

GEFS has a cutter signal around the 11/12th. But it’s super warm ahead of it. We need that west coast ridging to pop and then wait a few days at least to start flushing the puke out of here before we get some legit threats IMO. Maybe there’s a needle to be threaded before that, but just no cold air to speak of. If the ensembles are correct, I think we’re in business after the 15th.

Anyone in NE MD get any snow this morning? Radar looked briefly impressive.

DT’s back on board

Agree, if we’re going to get things lined up in our favor, the last 10 days of January and first 10 days of February is an ideal time for it.

Yeah that’s a very nice look.

More the opposite. Often a series of cutters “carves” the baroclinic zone eastward progressively. That’s why follow up waves work for us sometimes. I’ll hold you to that

If you assume the GEFS is a similar evolution, and it looks to be, then you can see the end of the 18z GEFS has 850mb cold anomalies filling back in over the CONUS. 2m temps lag a bit, but generally the same idea. Once you cut off the PAC firehose and get some meridional flow from Canada, you’ll get BN temps eventually with that H5.

I’m 0.1” short of last winter Yeah, I think BWI was like 1.5” last winter and DCA was under 1”?

Next ~2 weeks aside (and there's still a chance of some frozen precip on Sunday/Monday), I think there are definitely more signs to be positive beyond that then negative. Doesn't mean this will end up being a memorable winter, but I don't see any signs that it's a repeat of last year/11-12/01-02/etc.

I think it's probably a situation where both are somewhat correct. In a smoothed ensemble mean, you often don't see sharp ridges or troughs due to orientation, timing, and other differences between each member. So even if all the members have a nice NAO ridge around a given time +/-, when you average them all together, it may just look like what you see in the long range ensemble mean or weeklies product. As @Ji said earlier, we actually haven't had a true NAO ridge yet. That can has definitely been kicked a bit, although it does seem like a real one will develop as we start January.

Basically, anticyclonic flow over a region is a ridge. When it's oriented in a way (east-west across Greenland and Baffin is ideal of a NAO for us) to disrupt the zonal flow it's a "block". @CoastalWx is talking about this in SNE also I see.

@tombo82685 was talking about that "NAO" block on twitter a bit. Specifically, high/AN heights in Greenland/Baffin vs. a true ridge in that area. Mostly what those weeklies maps show is high heights. Now that might mean there's a ridge there at times, but AN heights alone don't act as a "block". Here's the 18z GEFS showing a true NAO ridge: Now toward the end of the run is just AN heights through the Baffin Straight: Now to some degree, that's probably just the ensemble mean smoothing things out. A real NAO ridge will pulse and vary as waves break, etc, so that could be what ends up in the means at long range.

Saw it posted on another forum

Apparently that beautiful H5 look on the week 3 map gives us a +8F temp departure!? lol that’s pretty amazing

Nice. That week 3 map you posted is fantastic. I think week 3 has some skill per the metrics, although anything beyond that is pretty useless I think.

Apparently euro weeklies went straight weenie party today after being very Nina-ish up to this point the last 2 months.