csnavywx

Agreed on the big dog. We're waiting until the 12Z runs tomorrow at the office. Should have the main players mostly nailed down at that point. I'm personally kinda split between a solid 12-16" or a 9-13" w/some trailing mix.

More like orange at this point. All systems go for red tomorrow if this holds.

The floor is rising. 18Z runs are no longer slowing down the southern stream and we have some buffer room if it decides to come more north. GFS is no longer the odd man out. I do expect the NBM means to peak right around now as some of the extreme tails get clipped (and there aren't that many duds left to fill in). So don't be surprised if that comes down a hair. Should be able to do a first guess map by tomorrow at this rate.

AI-GFS considerably north of 12Z run. ~0.8 QPF for DC; ~1.1 for SoMD.

Yes.

Short range errors on the southern stream cutoff are still pretty damn high. Still have a full day until that thing cuts off under the ridge, so we may not be rid of trends related to it until that occurs (tomorrow's 12Z runs, in other words).

Getting sold on at least a very solid front-end thump. I had some concerns with the slowing trend in the southern stream. 6Z GFS finally flipping away from holding the cutoff back makes me think that failure mode is sliding off the table. It was an outlier ofc, but if even the outlier is moving away from that scenario, it makes it less of a threat. The TPV has trended slow enough that the eastern lobe of that cAk high pressure will be solidly in place to prevent the incipient low from moving west of the mountains. So the question is now how clean of a coastal transfer we get and how far north that occurs. A phase between the cutoff and the trailing N/S wave would cause the WCB/warm nose to advance further north and perhaps cut into totals here. A partial phase or a simple kick probably still doesn't. But something to look out for on the latter part of the storm.

Depends on how the trailing northern stream vort goes. A phase there makes it more likely. But, usually, in order to get the biggest totals, you need to smell the sleet.

Good thing about the 6Z GFS coming into line is that this lessens the risk from the southern stream/cutoff. It was consistently the slowest and most guidance has trended slower and stronger with it over time. Gives some confidence in it not getting stuck or coming out too piecemeal. We have other potential issues, like interaction with the trailing NS wave, but the big failure modes are getting crossed off first.

Still want one more day of runs before I start barking. Time enough to let the SW cutoff and northern stream settle down.

If we're doing verbatim, quite a bit of mixing on the southern half of the 12Z run whereas virtually none on the 18Z and surface temps in the teens and low 20s. Anywhere near 1" of liquid in those conditions is gold.

Remember to use "max temp in profile" maps where possible or take a look at 700mb even if the 850mb-SFC maps are all below freezing. Warm nose can get pretty elevated in these scenarios.

The one nitpick I have is that the lead TPV lobe is slowing over time, strengthening the eastern lobe of the Arctic high. If it were sliding nicely off the coast, I'd agree more with him. Probably aborts the cut and forces a transfer earlier than the 06Z AIFS. The 12Z runs came back down to earth a bit.

Normally we lose out in these CAD-type storms. This one looking different. Northern stream looks strong and suppressive and the subtropical jet is finally coming back from the dead.

Low key had a lot of 1995 analogs pop when I did my seasonal for the office this winter. It was strong enough that I've got a wager going for a 20+" seasonal here. Doesn't mean we're getting the nutty 50+ that season had, but not at all surprising that this stuff is starting to pop off now that WPac warm pool forcing is strengthening and Nina forcing is waning.

Agree. Hard to get a better large scale pattern than this for us.

Yeah ended with a little less than a quarter inch here. Quite a bit more on the ground about 10 miles north. We get another shot coming up this next weekend. Hoping the TPV and the NEPac cutoff low decide to play ball here. The floor and ceiling are pretty high on this if both cooperate.

Still going to be a day or two until the cutoff underneath the western ridge (that opens up and serves as the trigger) is well resolved. Good to great setup for it as long as the TPV doesn't overwhelm and the wave actually opens up in a timely fashion.

Correct

Well after this dud, we've got another shot this weekend. Finally a decent slider track. Boundary layer temps are super marginal and I expect we "waste" some liquid to cool the column via diabatic cooling. It's also during the middle of the day, but that's a little less of a showstopper in mid-Jan. The trough orientation isn't the best, so there's still a chance of a whiff, but there's at least some agreement between the RRFS, AIGFS and EC-AIFS on track now and it should be able to produce a decent band of accumulation on the northwest side.

CFSv2 has been doing that since 2020, give or take. A better system, UFS, is linked below: https://www.cpc.ncep.noaa.gov/products/people/jszhu/seaice_seasonal/index.html

Some mood flakes and a dusting to start the morning. But my current focus is on the upcoming pattern that looks to offer some real chances, including a strong west-based -NAO pattern. The first chance appears to be this weekend with a southern slider that, at first glance, appears to be a miss to the south. However, the track is very close to the benchmark for our area and it would not take much of a north trend to produce here. Temps are marginal, but evaporative cooling and melting along the system's northern edge could help produce enough diabatic cooling to support a changeover to snow.

Yeah, going to end up about 10-20 miles south. Got a few flakes so far this morning but the accumulating stuff is going to end up just south of here and probably just south of SBY as well. We've got at least 7 more days of this pattern though, so plenty of chances for more clippers.

Made a comment in the office on Friday that we may see a lot of last minute adjustments this winter as this is the kind of pattern where that happens. Shoulda taken my own advice. Monday was indeed *not* off the table completely and my original thought from last week is going to end up being at least partially correct. Still looks like a grazer, but it's going to be close for the southern end.

Great little storm. Nice dendrites for most of it. Monday's system is a miss to the south, but might give some crumbs to the NC and SE VA crowd. Hopefully we get a decent clipper track or the like next week.