psuhoffman

You're looking at the northern edge of "heavy" precip, I think, not sure if you're using .5 as the basis for that...but the GFS always tightens up the gradient on the northern edge. It is always, and I mean ALWAYS too expansive and not nearly tight enough with the sharp cutoff on the edges and tightens that up the final 24-48 hours. Instead of it taking 60 miles to go from .5 to .1 in reality it will happen in 25 miles and the GFS tends to smooth that out too much at range. That tightening accounts for a lot of that deterioration, it didn't actually shift south...draw a line across the middle of the axis of the heaviest qpf, and compare where it is from the start to the end...it only moved it a little...it just tightened up the northern edge a lot, which was to be expected.

What are you looking at? This is the setup for the day 7 threat. Monster 50/50 with a decaying -NAO over the top as the storm ejects from the rockies. Thats pretty classic. How good a pattern do you think we need to get snow? After that around day 10 the pattern reloads one more time with a monster 50/50 under a -NAO one last time before the pacific shifts by day 15. But we have 2 legit threat windows after the current storm before that happens.

Looks like the GFS shifted the axis about 50 miles south and the Euro 30 miles north. That's a pretty common compromise between the two when they diverge by that much at that range.

They met in the middle, which wasn't good enough for you, you needed the northern most camp to win 100%.

I get 17", not road tripping for 24", if I was getting 2 or 3 definitely. You're welcome to come up here though, its only a little over an hour. I stopped in the sheets in Leesburg on my way back from IAD this evening.

You get more than NYC so you must be happy

this

A LOT of that qpf in Richmond is sleet and freezing rain on the GFS. They do get about 4" of snow and sleet. This isn't as crazy as the CAM models but it doesn't look as bad as you are making it out...

A couple of those sites probably...but if this pattern produces just a fraction of what it is capable of those numbers will be dwarfed by reality in the next few weeks.

Did Richmond and Salisbury just get out of the pool?

I didn't know there was a thread for that...guess I should move my map there ETA: Oh do you mean the seasonal contest snow predictions? LOL probably. I'm glad I'm going to bust! I said the biggest possible cause of a positive bust would be in the PDO were to go through a phase flip by January...not even to positive but just out of supreme negative territory towards neutral and it did. I just didn't think that was going to happen...it literally never had before in any example where the PDO was that consistently negative in a cold enso year heading into winter.

Can't say for sure...but the snowfall contours will probably sag southeast some across PA once east of the mountains due to the confluence increasing to the northeast. The storm starts to get compressed as it hits the effects of the 50/50. The odd part is the warnings going back north again near Philly. Some of that might be counties not following the exact lines they want, and some might be disagreement between CTP and PHI and lack of coordination as you said.

The signal on the EPS is about as strong as you get for a possible snowstorm at that range...even better than it was for this current threat when it was at that range. If we didn't have a warning level event 24 hours away we would be blowing up this thread right now.

There will be a sharp cutoff once you get north of where the banding close to the northern periphery sets up...but I think it will be like 20 miles further north that CTP does...which isn't that much of a difference. NWS thinks that sharp cutoff will be right near the PA line, I think it will be 20 miles into southern PA. I would include the southern most counties in PA but that's really only a one county difference which is nothing and a noise level error, but of course the people living in that one county don't want to hear that!

My thinking right now... I think the globals are underestimating QPF a little bit in the H7 FGEN driven banding near the northern edge. This happens a lot. It's not 100% but I just have a hunch...1000mb lows that make it into central KY on a NE trajectory and no arctic high on top just don't tend to dry out THAT much. Yes it will hit a wall of confluence but often that even enhances the banding on the norther fringe where the moisture transport hits that wall and you get some nice banding. But I admit I am going out on a limb and riding my gut here. But it doesn't take a huge adjustment from where the GFS and Euro are now, shift the northern edge of the precip 30 miles north and beef up the qpf by about .1-.2 in that northern periphery where the h7 forcing is located (and models often under estimate), add in high ratios and you get this. The other snowfall max is to our south with the h85 driven forcing.

I just got home so I figured I would put out a map now that I have access to a computer. I will probably have to adjust this some tomorrow but this is my thinking right now.

By hour 12 you can already tell where the hrrr is heading. If you pull up the rgem for instance it’s night and day apart by hour 12. That doesn’t mean it’s right but if it fails it’s not because it’s out of range. The divergence happens in the first 12 hours.

I feel pretty good about this...

Fair enough but that means you own that snjokoma poster that shows up to junk up the obs threads every time!

I types that up just before the run hit. The euro did almost exactly what I hoped and now looks really close to what I envisioned. I’d maybe expect another slight beefing up of the QPF along the PA line area but not much. Maybe another .1 qpf. But that’s another 1-2” which gets that area into that 5-8” range I’ve been thinking all along.

The northern MD crew doesn’t need it to trend north. There is a legit path to a full forum win here. If that h7 driven band on the northern fringe beefs up just a bit as it often does at the last minute, and the h85 driven band stays where it is, we could get a full forum EZF to the Pa line warning event.

I didn’t think I’ve been negative.

It’s late and been a long week

But more realistic I want it to hold its 18z run but beef up the qpf in that northern fringe band like .1-.2 qpf.