CAPE

Not looking great, but like I said yesterday, a 'good' outcome with this realistically is rain ending as snow with a coating or maybe a bit more, if there is a bit of a trailing wave. GEFS still suggests a period of snow is possible as the cold comes in, while the EPS has the trailing wave further southeast- best chance for the cold to catch the precip for a little snow as depicted is probably eastern VA. Still time for this to degrade into the usual case of cold chasing rain though lol.

Don't get me wrong, the historical data is clear about the importance of a -AO (and NAO) for cold and above avg snow in and around the DC area. I am happy with snowfall of any magnitude, but clearly bigger storms- which is almost always how we get above average snowfall- are favored when we have HL blocking. Now maybe that data isn't as reliable now and esp going forward due to a warming climate, but that is conjecture at this point.

This is certainly a colder look than we have seen should it verify. I guess we will see if clippers still exist, and if so, whether or not they can still track far enough south. But yeah not much help in the AO/NAO domain as advertised. Chilly and dry would at least make it feel more like winter. We really need the MJO to keep progressing into the better phases or this decent Pac look likely won't persist. If the forcing craps out in 7 or just as it gets to 8 then re-fires near the MC, the Pac ridge will retro and strengthen again and we will be back where we were, and maybe with no Atlantic help. I remain optimistic though. Intuition!

I see the optimistic half cycle of the weather weenie bipolar waveform has ended, and we are approaching the negative peak, 'gloom and doom'.

Getting snow with the colder air just coming in is a tough one. Really need a pretty healthy wave but not too amped and ofc timing. Always timing. A realistic 'good' outcome here is probably a few hours of snow on the tail end with a coating to a couple inches. That's probably just my intuitive thoughts on the situation though.

The signal is there on the GEFS, but suggestive of a progressive/weakish trailing wave, and a decent chance the precip exits before much cold can get involved. That said, there are 9 or 10 members that imply a coating to as much as a few inches for at least part of this region.

The southern energy hasn't come ashore yet. Not properly sampled.

Ensemble guidance in general suggesting a significantly -WPO, slightly -EPO, and slightly negative/neutral PNA in the LR. AO/NAO look generally neutral. Also seeing a possible southward displacement of TPV over Hudson Bay. That type of pattern should provide more cold air chances for the central and eastern US.

6z GFS is more amplified with the NS energy getting involved/phasing, but the depiction at the surface is a little odd based on the upper level look. Upshot is it's a NE snowstorm this run. 0z Euro/EPS has a much weaker wave tracking along the boundary and the cold air is late to the game. CMC leaning this way as well.

Looks like Truckee has a good 3 feet of snow otg.

Avg annual snowfall must be higher a couple hundred miles east of me. Baroclinic zone is foo far offshore during much of winter. Fish snow. Ji was wrong about me living in the ocean, but I probably should.

Ha they always fail, but half the fun of this silly hobby is just having something to track. A chance. After a prolonged period of 'nice' weather with really no shot, this probably is the first legit chance for a light, maybe moderate frozen event for at least part of this subforum outside the highlands.

As depicted this run, pretty textbook for a moderate snow event. Notice how the Highs and Lows are in all the right places.

CAPE storm is still alive.

Eh, a shake up in the pattern might be good. We are damn good at failure regardless. Let the Pacific drive and hope it's not cutters followed by cold/dry. Maybe we do a mini version of 2014.

+PNA

Next panel is better. Lewes/Rehoboth bullseye. It will probably happen as I will be heading in the other direction.

Sorry I don't do snow maps.

That vortex near the Sea of Okhotsk isn't weakening as much/as fast on recent GEFS runs. That would continue to enhance the strength/stability of the Aleutian ridge and delay the western US trough movement eastward.

A fixture in the +TNH is an EPAC ridge, same as a Nina. Flattening the SE ridge with the current background state likely requires favorable shifts in the configuration of the NPJ, and MJO (and continued help from the NAO). Seeing a much more serviceable Pac advertised on the means in the LR but no idea if it's real yet.

-PNA!! I start looking at op runs when we have an identifiable threat inside 7 days. Why look at advertised longwave pattern stuff on an op 10+ days out when it dramatically changes run to run. Looks less scary on the GEFS.

This upcoming period has consistently looked to feature a transient eastern trough with a ridge building right behind it on the means as the trough(temporarily) re-digs out west. The window is brief and pretty much centered on a wave forming along the boundary. Too soon to know if it will be weak, shredded, too warm,(insert other failure mode), etc, but the idea is still there on today's 12z GEFS.

At least I can say I have observed a few minutes of frozen in December, to go along with the few mins of flakes in November.

Sleeting in Easton.

Chuck! +PNA