Newman

Yep, the Euro went the wrong way with this and heights don't respond at all

Yeah Canadian is also much better. I don't like this setup because it's inherently volatile and dependent on getting the trough to tilt negative at just the right time. The ridge being through Montana and not Idaho could be the difference between a NW of I-95 storm or a SE of I-95 storm. Obviously lots of time to track and I think the entire subforum is still well in the game!

GFS is going to be significantly improved

I know models all shifted east overnight, which remains the fail mode, but we're not out of this by any means with lots of time left. We need to see improvements in the wave spacing between that system that exits CNE Friday/Saturday and our NS wave diving out of the Dakotas/MN. Pump the ridge more, inch it further west, and I think we can get that shortwave energy to round the trough enough for at least coastal areas. I'll be honest though, this setup now reminds me of last February's fail which ended up way suppressed and OTS. It has powder keg potential, but probably a lot lower probability from what we saw in previous days

I was literally going back in my images to look for that exact run What a fun storm that one was. For me personally down in Fleetwood, I enjoyed it more than 2016. We got more snow and, although rates never exceeded 2" an hour at peak, it snowed literally for days.

It reminds me of some of the wild RGEM/CMC OP runs from 2021 ha

This 96-132 hour range is where we've been at on a few occasions this winter, and ever since the beginning of weather tracking itself, that models begin to trend towards less favorable outcomes. I'd say 8 or even 9 times out of 10 when a MECS/HECS is seemingly looking likely, it falls apart in this specific hour range. It's all fun and games until the NAM is in range. There is no such thing as a rug pull at this point, we have so long to go. One of the more discouraging shifts in NWP in recent years has been the lack of confidence gained from some ensemble guidance. And what I mean is the EPS and GEFS tend to follow the OP or be incredibly underdispersive. Despite some gripes with them, the ensembles are truly our best form of guidance at this range if you know how to use them. These pretty snow maps from the deterministic models are fun to look at, but they're purely entertainment at this range. With that in mind, if you blend the EPS, Euro AIFS ENS, GEFS, and CMC Ens... You find that you're basically split 50/50 on a hit or miss. The good news? The EPS has been trending towards the big solutions. And the GEFS is just a bad model, so who cares lol.

Euro AI is east of 6z but still not bad for much of SE PA at all, widespread 6-12" with more along the Jersey coast. Well within the ensemble envelope at this range.

A pretty much perfect progression. Capture and stall off the Jersey coast, it occludes so you get snow right down to the LP center

Holy shit CMC!

GFS just a bit too disjointed with phasing in that NS vort, verbatim it's still a huge hit for coastal Jersey. This 12z run is also completely different with how it handles that southern vort, it's amplitude, speed, etc. But I guess it goes to show that it's not a thread the needle scenario, we can score in different ways, though some locations will be favored depending on the final evolution. GFS being SE at this time though is classic, you wouldn't expect anything less. Actually looking at the final GFS solution, it's just a tad too late with fully phasing hence the strongest PVA is offshore and into Jersey -> NYC -> SNE

ICON starts us off great at 12z, 18-24" from Philly to NYC

I definitely understand the worry with an interior event, the AI GFS is essentially that. But seeing a pretty clear SE leaning cluster on Euro ensemble guidance tells me that's the most likely fail right now. Outside of the January storm, mid-range guidance has been seemingly too phase happy/amped this winter. I don't want to go against that seasonal trend based on current model guidance. We're also at that stage where we start to see storm evolutions warp, shift, and change. Probabilistically anything is on the table, and quite equally IMO. Excited for 12z runs as well

Have not been keeping up with this storm threat but might start doing so now that family is asking all about it ha. That 6z AIFS run is near mint perfection. Like Ralph said, a quick glance at the upper levels and you can tell the fail mode here is a slip east

2" in Fleetwood

Just a tiny difference between 12z and 18z RRFS. Something must've gotten into the NOAA mesoscale products at 12z LOL

Euro is a general 1-2" for most, maybe an isolated 3" in Jersey. That's what my forecast would be right now. Most accumulations on grassy surfaces, slushy inch or so on paved surfaces when rates are heavy enough.

Welp the NAM, HRW-FV3 suite, and RRFS are all showing real solid hits now

NAM is widespread 3-5", lolis of 6" across SE PA. I do think this is one of those overamped NAM runs, especially with how stark the difference in that NS wave is from last run. Really want to see Euro jump on board with a sharper NS wave.

I'd love to read Mount Holly's night shift AFD on this one

The last 5 run trend of the GFS is wild, at some point do we see this stop trending? I still think this run is over the top and we see something more like the ICON or Euro, but it's been a long time since we've seen such significant shifts in guidance to produce a *favorable* outcome within 72 hours of an event

GFS is a real solid hit. Are we really doing this? Lol

GFS looks solid for SE PA. Like I said, keep ticking this slowly each run up until Sunday night and it's gonna be a legit storm

The Euro OP showing a similar shift is intriguing, as well as other guidance shifting towards it. If we can slowly tick that southern vort more progressive and that northern stream a tad slower/sharper from here until game time, we'll have a snowstorm on our hands. Still not buying it yet, but the 12z EPS is way north as well

Here are the individual AIFS ensembles. I counted about 24/50 members have plowable (3" or greater) snow into Philly. Just about that many have 6"+ or even 12"+ as well. Truly boom or bust. It all depends on if we phase or not with the NS wave. Let's ride member 29, 46 or 50 and call it a winter. And just to clarify, I'm not calling for a significant snowstorm with this one yet. I will need to see substantial shifts in other guidance and for the AIFS to hold the line in future runs.