NJwx85

What a mess and what a shift. Two closed upper level lows. The initial one and then the trailing one.

Looks like it closes off the ULL over the Carolinas.

Certainly no worse than 06z and looks to be further West and stronger.

92 members here and nobody has paid access for the Euro?

The trough axis is quite a bit further East and sharper, again based off the free maps on Tidbits.

The Euro looks like it's digging the trough more and it's significantly sharper at hr 24. Can't see the 500mb vorticy off the free maps but looks like it might have ejected the SW energy faster.

Very rare to see the Euro make big jumps inside of 96hrs. It's usually painfully consistent and slowly moves towards the correct solution over many runs. It did horribly with January 2015 and many people incorrectly sided with it over the GFS. If the NAM agrees with the GFS, it's usually game over. That hasn't happened yet.

The wildcard is if the models are closing off the ULL too late. Even the 12z GFS closes it off which was an improvement, but not until SE of Cape Cod.

It actually looks like we're moving towards a consensus. Heaviest snow Eastern LI up into SE New England. Everyone else glancing blow. Don't think 6-10" is out of the question yet for NYC, especially given high ratios.

Must get that Southern stream vort to eject out ahead of the digging trough. Only two ways to make it happen. Slow down the Northern stream or speed up the Southern stream.

No, to get a dry slot the ULL would have to come onshore. It's going to pass Southeast of LI.

If the 12z GGEM had closed off the ULL 6 hours sooner we would have all been measuring snow in feet. Instead it closes off 6 hours later South of the Twin forks. It's that close.

The 20"+ amounts from a few days ago are off the table but this will still be a double digit snowfall for many with potential for a few surprises depending on where the best banding sets up. The 12z GFS was actually quite a bit better. If you look at the last four runs of the GFS at 500mb valid 18z Saturday, the position of the ULL is actually back to where it was on yesterdays 12z run. It ticked East at both 18z and 00z, then back West at 06z and now at 12z. The last three runs of the GFS have also trended towards the ULL closing off sooner. The Northern stream shortwave has also slowed down considerably the last few runs. If that Southern piece can get out ahead of the trough, it will dig more, amplify the trough and we will be in business. Not saying that will happen but that's what we need at this point.

Not a chance. That was a relatively weak low that crawled because of enormous blocking.

00Z NAM is running. So far looks like less energy is being held back in the SW.

The long range NAM is fools gold with East coast storms. Doesn't matter how many times you say it.

Every time a big threat shows up people give the long range NAM more weight than they should even though every educated poster says time and time again how it cannot be trusted. In this type of setup you want the NAM beyond 48hrs to show rain for Long Island and Boston in order to feel confident. It's always overamplified and corrects inside day 2.

The NAM is going to be way East, like the GFS.

I see very subtle changes so far on the NAM. If anything the southern stream energy looks stronger than 12z.

This is what I spent nearly 10 posts trying to explain but some people just don't want to hear it. You cannot just look at the surface. The surface is for weenies.

I don't know if I would use the word most, but it was a fine run for the time frame that we're out. The GFS and the Euro are still more than 100+ miles apart in terms of how far West the significant snow gets.

As mets have said, we haven't established any trends yet. It takes at least one full day of model runs to establish that. You cannot expect models to show the same outcome each and every run. You have to look at what's going on in the mid levels and see if what's depicted makes sense. Clown maps are called what they are for a reason.