csnavywx

You got 11" and a blizzard warning a few years ago, right? '17/early '18 was it? Or am I misremembering that one.

It does look like we're going to get another swing at it in this pattern later this week. The chance of a repeat "phase-miss" is lower this time. Regular reminder not to get too carried away with any one run or model. I want to see this trend stick through the 12z guidance tomorrow before I start investing.

Sorry, but a low that has a genesis off of FL is not a Miller B. Not in any book I've ever read or studied. Wish we'd stop with that.

The phase is still a pain point, but that seems to be working out as the northern stream wave has trended slower. There's room for improvement on both ends, so long as the phase is still on the table.

Who honestly believes, that after the typical block breakdown mishandling, that it won't also display the sub 72-hour slow NW walk? So long as the phase holds, I posit that it will. Also, better horizontal resolution absolutely does improve handling of all of these interactions. Take a look at H5 vort on the NAM 12km vs 3km at tau 60 on this run and tell me that the 3km wouldn't be even better. Block is slightly stronger and phase is slightly better.

Hey, that omega block is breaking down slower than forecast a few days ago. What a shocker....

Yep, did some scoping on west coast initialization, they're a dead match. Good against RAOBs too. GFS was a touch weak out there (10-15m) at 500mb on the ridge.

Yep, we are pretty dependent on that ridge with a lack of a downstream block to slow it down (as @wxmvpete) mentioned.

CMC demonstrating nicely exactly what I was referring to earlier. Cutoff/omega combo breaks down slower, allowing the downstream to amplify more. That's good for us. Don't worry too much about the "tail" vort streamer. We want one there. This wave is big enough to scoop that out and give strong advection vort to spin up the low faster. Now the next question is -- are the models demonstrating the typical bias in blocking breakdowns and simply correcting for it over time now? It's always been my experience that there's a tendency to break blocks down too quickly. Some of that probably has to do with the limitations of horizonal resolution on a global. Smaller scale eddies are important for maintaining blocks.

Need that upstream omega to break down a bit slower. That cutoff offshore of CA being slower helps this run as it doesn't dampen the ridge as quickly. Lots of run to run variability until that piece settles down.

The rolling and demise of that upstream omega block is going to be key. The cutoff well off of CA is a sticking point. The primary reason the GFS shifted was due to the ridge axis being distorted as the upstream cut-off opened up into a wave and destructively interfered with the ridge axis, causing our downstream trough to be less sharp and ultimately less vort advection. Takes a bit too long to get going. That said, we're in a good spot and the fact that all 3 OPs are flagging something to watch at this distance is also a good thing.

Still not dead yet. Though it looks like LS over in Salisbury has a better chance than the rest of us on Fri night into Saturday. Front is slower than originally forecast and I expect the northern edge of the precip shield to clip us. The northern cutoff between virga and accumulating snow will be sharp. You will either be in it or not, generally speaking. Not the big storm I'm sure everybody was rooting for earlier this week, but never take your eye off a southern slider. They can sometimes bite at the last second.

If these changes carry over to the 12z runs, then I'll be on board. I want to see it survive a few initializations. Everything was slower on this run, and not just the main players. Could be running into the same issues again tomorrow -- and that matters when it comes to the NS wave being able to amplify instead of getting impinged on by the upstream NS kicker.

Good house line. I'd be betting against. That run last night had heavy Everest vibes.

Yes, I like slider-type systems for this area. We're in better shape than we were even 24 hr ago. Just need the southern stream wave to phase, even partially will do it.

To be expected after the Mt. Everest of Euro runs last night. There was nowhere to go but down from that one. That's why it's important not to bail all-in until more evidence accumulates. We're just not quite there yet and given the sensitivity of the positioning of the southern stream wave, it's probably not going to be all that clear until late tomorrow.

Yep, that wave train can go on for quite some distance after starting! The waves will duct inside the unstable/stable layer couplet until conditions change downstream. In this case, that's well offshore, even past where they can be seen via cloud condensation.

To be more specific -- this is being caused by perpendicular flow over a barrier (mountains in this case) and a stable layer overlying an unstable one. Note the dry adiabatic layer from the surface to about ~875mb and nearly isothermal/stable layer above that. Air is pushed upwards by the mountains, ascends and then begins to sink again as it enters the stable layer, causing it to accelerate downwards. It will then sink and accelerate upwards again after entering into the unstable layer. There's enough moisture in this layer today that some of it condenses out on the ascending portion of the wave. It's a dead ringer for mountain wave turbulence and I use it all the time in turbulence forecasting.

Mega-weenie run, jfc.

This entire run is a giant tease, especially for my neck of the woods. I get the feeling this is Everest. Rips the sleet/mix line to within 15-20mi and then just stops and crushes. Can only go downhill from that one. Would be thrilled with half that total, tbh.

Threat level gradually rising. Hoping it doesn't amplify *too* much at this point.

Man, I'm aging myself. It's Captain Caveman.

Live look at the GFS:

No thanks. Way too far west for that, phase or not. Hard pass. I'll flip to bearish on a dime if that were to keep up. Luckily, looks isolated compared to the mean.

RGEM upstream kicker over the PNW is quicker this run, making the southern shortwave move a bit faster. Good run.