Bob Chill

Just caught up with the overnight runs. My suspicion of the 12z Euro yesterday being too fast (unfortunately) appears to be the case. Plenty of lead time to watch things evolve and we won't even be back in the game until the prog'd cold front pushes through here mid next week.

Just so we're on the same page... Unless there's a transient 50/50 or a very lucky track, the general setup favors a west track by a good margin. Ops and ens are showing a pretty decent cold hp to the north and a decent cad signal. Get something to come at us from the TN valley with a departing HP to the north and it's one of the most common ways we get a light or moderate event but not all snow. Last 2 gefs runs support the general idea as does the eps. All we can do is discuss the potential in general terms. This is the best shot at winter wx I've seen so far. It's flawed and unlikely to be all snow if it snows at all. No reason to poo poo it or go all in yet.

The exact snapshot on the euro was a big storm look. Ens support the idea but they also support rain, mixed, or nothing at all. A lot has to happen first. Once the full latitude trough/front clears then any shortwave zipping along after has potential. We're 5 days min away from models focusing on a discrete shortwave that actually exists. Overall the setup is so-so but it's our next chance so it will get a lot of attention.

MSLP panels look pretty good. CAD sig in place and low pressure to the SW. I'd be perfectly fine with a west track front end thump. Whatever it takes to get on the board with something other than a T

Don't stress man. Odds strongly favor things not working out.

All in good fun being so far out but this would be an all frozen storm for most. Especially west of 95. No way this depth of CAD gets dislodged. ETA: Surface wind out of the N/NE all the way down to GA. Notice the little spin near Savannah GA? There's the jump. lol.

Just a hunch but my guess is the euro type scenario is too quick. It sure looks like the best chance of the season is setting up near mid month though.

CAD/block will win the battle here.

Euro/GFS look nearly the same with the EPO ridge closing off and creating a block. This is getting very interesting. Big storm potential at the end of the euro as well. Prob too fast but late next week in becoming increasingly intriguing.

GEFS is showing a decent threat window from the 15th-17th. The mean jumps from practically nothing to this in just a few days... QPF/MSLP panels also show a coastal track. This is the first time I've seen the GEFS latch onto a specific event. We have 12 days to over analyze and freak out.

GEFS looks as good as you can ask without a -NAO... Split flow, broad trough, nasty EPO ridge dumping arctic air, -AO building to keep the TPV from running away....

I'm digging how guidance is shifting towards a more broad conus trough down the line instead of a vertical ridge/trough setup. The broader the trough axis the more chances we get for a widespread event instead of praying for a perfectly timed shortwave to round the base and praying even harder that the 100 mile wide swath of precip makes it over our yards. Lets have a big drawn out overrunning event that plasters the TN valley and MA.

If the 12z gfs -EPO on HGH and steroids happens then we don't have to worry at all. A giant closed off upper level ridge in this area will continuously dump cold into the CONUS. Probably for weeks. lol Of course this is fantasyland stuff but the -EPO ridge builds within 5 days and just goes bonkers from there. Keeps looking blockier in the long range too. Like many here, I'm feeling good about the second half of Dec

I'd be good with that. Honestly, I'd be good with a repeat of any year that was decent in the high latitudes but ended up crappy because mid latitude stuff screwed it up. Conversely.... I wouldn't want to take my chances again with a 2013/14 pattern. That year was famously amazing but the way things happened defied a more typical outcome. Next time we get an -EPO/++AO/++NAO pattern I can almost guaranty nobody will be happy with the outcome. lol

I honestly don't worry about the MJO much unless it's an amplified wave in the crappy sectors. Since mid Nov it's been either a weak signal or in the COD. Ens have been agreeing on a weak trip in phase 2 and back to the COD and that's been going on for most of the last week although I don't check every day. Just a quick scan once in a while so my MJO obs could be flawed. The AO flip was well modeled by all ens and even ops. It's almost a lock that the east gets at least a brief warm period after the AO flips positive and that appears to be verifying over the next week or so. Back when the AO flip was first showing consensus it looked really ugly but thankfully that's backed off and the current +AO flip appears to be short lived and inconsequential in the bigger picture. The nPac appears to want to play nice and that's the best way to avoid a +AO shutout/torch.

Digging back through the last week or so of ens runs, one thing does stand out with the EPS. The EPS has had multiple false signals of having a trough dig into the GoA or west coast in the long range. The GEFS/GEPS have been more consistent in showing more of a +pna and/or -epo building. Could be the MJO forecasts or it could be some sort of inherent bias. Don't really know the whys but the GEFS/GEPS appear to be verifying better d10+ in the Npac versus the EPS. Something to keep in mind when comparing ens runs in the LR.

My father taught me the #1 rule... Guard your tool. Doesn't mean crap in wx but it's still a very good rule

I generally look at the height fields and not numerical indices but the graphs are telling us something... Every major teleconnection has been zig zagging (that's a technical term) since mid Nov. There is no stability or persistence with long wave features. You know what that tells me? It tells me not to make any fast decisions/predictions about anything. Looks like we have building consensus for a +pna/-epo/+nao period coming up. That's enough to keep us in the game but the game will be difficult to win. Beyond that? Good luck guessing.

Webb jumped on the ens too quick. That look was fleeting and sporadic and not a building signal. There were plenty of conflicting signals at the same time but Webb wanted to be first to call the torch.

18z gefs actually supports the ops idea. Unusual to see qpf panels like this 300 hours out.

Just be patient. Even though it looks like we go back to bn temps after a nice warm day or 2 next week, pulling an event out of the progressive flow with no block requires a lot of little things to work out. Most importantly tight spacing... Each airmass capable of producing snow will only be in a good spot for 2-3 days tops. Miss that window and the next event is likely rain. It does look like we're moving back into the game mid/late next week. Would be nice if the +pna pattern hangs on for 1-2 weeks so we can get more than one isolated chance at threading the needle

@MillvilleWx would get a foot of ice before me. That sucks. All I want is a cat 5 up the potomac and a foot of ice. 2 very simple things and I'm not getting any younger so it better happen soon

Imagine it? We've lived it more times than anyone wants to imagine or remember. Half a dusting kicks my yard's ass though. I have half a swamp so at least I got something

But you said the southern stream was dead

These types of setups are notorious for underperforming. The disjointed surface and upper level low aren't in sync. Not much heavy/banded precip. If the airmass was cold it would have been half decent almost everywhere but fighting marginal rates at 33+ degrees is always a bummer. We do that really well here at times. Lol