Bob Chill

Euro control on the weeklies yesterday has a white Christmas Eve and Day.

I'm pretty optimistic. I'll have to dig through the spreadsheets to get hard #s but going off memory, a strong blocking event in late Nov or early Dec is the more common "kickoff" to a -AO winter. 12z GEFS shows a way to avoid a shutout pattern while the pac goes to hell. Decent setup for confluence and high pressure to the north late in the panels. Won't be uber cold if that type of look verifies but just having a typical/marginal HP in a good spot can work in December.

Sort of. We need -1.25 monthly mean or lower for it to be significant. Data supports an 75%+/- chance at above normal snowfall and blocking to persist through Feb. The years that broke the wrong was had a terrible Pac though so it's not a slam dunk but certainly a good sign seeing a persistent -AO right now.

More notable improvement on the 12z GEFS for the d10-13 window. That's obviously the best shot considering it will have the deepest cold to work with. If we did squeeze out another couple inches of snow it will solidify a solid start to the season with 2 or more accum events before mid Dec.

BWI: 26 DCA: 16 IAD: 29 RIC: 14 Tiebreaker: SBY: 12

There's some minor EPS/GEFS support for the potential. 12z gefs moved ever so slightly better. We'll see what the euro/eps does shortly. At the very least the trend last few runs has been better instead of worse. We usually back into most of our events and a lot of time for things to move around.

Yea, when you see exceptionally strong anomalies at long leads like we are seeing now then it's prob going to happen. It's kinda dumb to get worried about something being persistent when 1) it hasn't happened yet 2) is counter-intuitive to enso 3) it's not even Dec yet. Just bringing up the point that it's one of the things that has spoiled winter in a big way in the past. If we're still staring at an AK blue ball around Christmas we can proceed to full blown panic as a bootleg/transient NAO sets up and it snows a foot in the worst possible pattern.

2 weeks

@frd I have no idea if it's just part of a rolling pattern or the deep AK trough/vortex is going to be a dominant theme. It's ruined winters before and that's why it's hard to look at. Brings up the conversation of how winter in the east half of the conus can be ruined. It will be a collective sigh of relief of weenies everywhere if it's transient.

The good news is the ens are showing just about the worst possible pattern for winter wx in the conus in early Dec so it can only get better from here. There are worse patterns for our region but that Pac setup... ooof. Hope it's wrong or hope it's transient.

Exactly. Weeklies were showing a very nice Dec pattern just a week or 2 ago. Now it sucks. So in another week or 2 it will be good again... and so forth and so on

Pretty nice cold shot before any mild period. 12z EPS looks better than the last 4 runs for a chance at something d8+

Pretty much a flood of pac air into the entire NA continent d11-15. Canada in particular. Too far down the line to get hung up on but it's not pretty to look at.

We'll most likely go through a "rough patch" during December but when don't we? lol. The last 10 days of the month is the beginning of our prime climo so if things are going to stink for a time then sooner the better. I'm not seeing the +EPO/GOA trough as any kind of ominous sign and thats if it even happens at all.

A trough in the GOA is highly unlikely to remain a constant feature so I'm not worried about it at all. I'm expecting the whole longwave pattern to roll forward over time and a +PNA (and hopefully a -EPO as well) to develop sometime near the middle or second half of Dec.

The "earn your turns" lifestyle was my favorite. Yes, I loved inbound lift access skiing but the "religious" experience was getting a small group of friends together loaded with proper gear (avalanche transceivers most importantly) and just going for it. We'd plan descents for days. Waiting for the right weather/avalanche conditions and then nervously going for it when things were right. Hiking above 13k' is on a whole new level of cardio. Your heart would pound in your ears for hours and you learn how to speed up and slow down your pace so you didn't need to stop and catch your breath every 10 minutes. Took 3 years to get in really good shape. I no longer needed to stop for anything after a while. The first few years I always thought I was going to have a heart attack or something. lol. The really weird thing is that below 13k isn't too bad. Almost easy in a way. Once you cross 13k the whole atmosphere changes. When dropping into the descent it was always heart in throat. We used to draw straws for who went first. Out of 100s of descents I only witnessed one serious avalanche and nobody was caught in it. It was a sympathetic release thankfully. We were pretty smart for dumb guys. We had the gear and we dug our pits and didn't take too many big chances but it was always on your mind...

This picture was taken yesterday from Arapahoe Basin in CO. Brought back a flood of memories of my years out there. I highlighted one of my favorite descents. Ridge access starts at the top of Loveland Pass. It's about a 1.5 hour hike from the pass to the circled face called No Name Peak. After skiing the peak you skin the lower ridge to the top of an amazing glade called No Name Trees. After skiing the trees your right back on highway 6 and hitchhike back to your truck on top of Loveland pass. The entire loop is about 4 hours and that includes plenty of sightseeing and goofing around in the backcountry. I did this circuit at least a dozen times when I lived out there. 20 years later and I still think about it frequently. I miss CO...

The repeating cold shot cycle is very encouraging. As long as that keeps up we'll probably just stumble into an event of some sort without needing the planets to align. Even though it's not snowing every 48 hours it does look like the first half of Dec will be the best we've had in the temp dept since 2013.

All the variations = the same outcome. Not ripe and not a disaster. Flow is loaded with shortwaves so anything interesting prob won't show up until the med range. Not expecting much personally but at least it will feel like early winter more often than not. We've had quite a bit of December warmth since 2014.

Euro op following up with the d10 -epo on the ens. This is a pretty good pattern for cold here (and most of the conus). Gefs and eps diverging with the Pac it seems. I'll hug the euro/eps for now...

Check out the d14 AO verification. Gefs is busting high in the long range. This is the exact opposite of the last 3-4 years. We're moving into prime time for the AO to be a meaningful long lead indicator. If the gefs keeps busting high then good things are probably about to start happening no too far in future. Like in 2 weeks...

@psuhoffman I've noticed the same with Cohen over the years. He's so fixated on the strat and treats it like a binary end all be all with winter wx in the mid latitudes. I don't get it. For every example that shows the correlation there's another that shows the exact opposite. Not saying the state of the pv isnt important though. When it's good it's really good and vice versa but that's only when the strat and trop act in unison. Which imho- is the minority of the time.

I could write a 10 page reply here but I'll give you a little tidbit to think about... The jet rides up and over ridges and rounds the base of troughs. When you have a trough around AK, the jet is rounding the base and heading inland. Meaning pac air floods Canada which is our source region for cold. A trough in the east favors below normal temps but when the airmass originated from the Pacific it's not very cold to start and then it modifies as it travels our way over several days. When the jet rides over the top of a ridge over AK it helps build cold high pressure just to the east of the ridge in western Canada. It also helps draw polar air southward in our source region of Canada. It makes a big difference too. Not just 5-10 degrees but as much as 30+ degrees between the two scenarios. Both our areas require below normal temps to snow in the heart of winter. We also require well below normal temps to snow early and late in the season. Areas like new England or the northern plains can get snow with just "normal" temps for those regions. That doesn't work here. We need deep cold air diving down from Canada to produce snowfall. One of the best ways to get that is to have a ridge over or near AK.

Beats cold and dry right? Much more common for a minor event to produce during the first half of Dec anyways. I don't even remember the last time we had a traditional coastal the first 2 weeks of Dec. Well... we've had some coastals but they are almost always rain. Ensembles are reminding me of Dec 09 right now. The pac jet was active during the first 2-3 weeks of Dec iirc before a more classic nino pattern set up later in the month.

I have to go back to SW CT from Dec 19th through the 24th. I'm rooting for miller b's and other MA screw jobs while I'm away.