CAPE

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

Oh its coming.

In the long range all 3 global means have a very serviceable Pacific look with the mean trough and cold directed more into the central US- and with the advertised look it would also be colder in the east. The differences are up top/on the Atlantic side. GEFS maintains a -NAO, EPS looks neutral to somewhat positive, and the CMC ens is somewhat in between, but has a colder look for the east overall. Maybe we lose the blocking for a time, but it has not done much good with the raging NPAC ridge. With improvements there, we should see more cold chances via a neutral PNA/ -EPO. eta- one other thing of note is the PV looks somewhat perturbed/elongated in the LR, and the indication of southward displaced TPV lobes can be seen on the mean. Not a bad look for getting cold air excursions further south.

The Euro ens tracks the New Years storm well NW, then has a trailing wave along the advancing cold front Jan 2-3 timeframe. Verbatim it would be cold chasing rain but still a week out so plenty of uncertainty, and we just cant know- although most of us probably have an intuitive feel for how it might play out.

Looking through the GEFS members, about half imply a more amplified storm that would probably track a bit too far N/W for much of our area(for frozen) but there are others that are less amped/flatter and colder, and there are a few that imply a second wave tracking further south on the 3rd.

My understanding is an extended jet places the exit region further east, which favors a ridge over the western US. This is more common during a Nino, while jet retraction places an anomalous ridge further west over the N Pac, and is associated with a Nina (Chuck's beloved -PNA!) Simple explanation. Cheers!

Too bad they didn't protect Trace McSorley, eh?

It's Complicated. Firstly a -PNA isn't always a bad thing. Jet extensions occur more in Nino, while retractions are favored in a Nina. A poleward shift is more likely in a Nina. MJO phase can have an impact, however. Don't quote me, but I think jet extensions in general are favored during MJO phases 7 and 8, so if we are in fact seeing an extension of the Pac jet (during a Nina) it is probably related to the MJO. What a surprise! I am sipping on my first bourbon after a couple glasses of wine with dinner.