RU848789

Thanks. Ignore the point and click when they're at odds with the issued snowfall maps. They'll update soon. Also if you go in to the hourly weather graphic it shows 4.3" of snow for Perth Amboy.

More pretty pictures...

As I mentioned earlier, the NWS said in their AFDs that they were closely following the NBM, so given that the NBM has taken a decent bump upwards (maybe included the NAM already) at 07Z, I'd expect watches to go up for anywhere that is at at least 6" on that map, which includes this entire subforum basically and the Philly subforum too (note that this map includes previous snow from the Catskills northward).

Yes, we've been NAM-ed. Huge to see even if it's a bit out of its range (the important changes were mostly earlier).

That's incorrect. NWS forecast for NB through NYC is 4-6" through 7 am Monday, which would be 5-7" through the end of the storm at 1 pm Monday, assuming use of the NBM (which they said they followed closely). See my other post with the maps and such.

I'd argue that the NAM at the end of its range shouldn't be used to inform snowfall forecasts. Also most of the 6Z models showed decent increases in snowfall for this subforum and the immediate NYC metro, as per below. Based on the models and the NWS forecast of 6.5" for CPK assuming they'd follow the NBM through 1 pm Monday as per my other post, I'd maybe say 4-8" is a better call for NYC Metro, although I an also see 3-6" being a good starting point with the high uncertainty and huge range we have over the models, as per the NWS 10% low and high cases being <1" for CPK to ~10" for CPK Just my thoughts. 6Z ICON shows 6-12" for NYC metro and 9" for CPK (big increase from 0Z) 6Z GFS shows 12-18" for NYC metro with 15" for CPK (decent increase from 0Z) 6Z AIGFS shows 10-14" for NYC metro and 12" for CPK (a big increase from 0Z) 6Z Euro-AIFS shows 4-6" for NYC metro with 5.5" for CPK (same as 0Z) 6Z Euro shows 3-5" for NYC metro and 3.1" for CPK (a bit of a decrease from 0Z) 7Z NBM shows 6-8" for NYC metro and 7.8" for CPK (slightly more than 01Z). The 0Z CMC/UK both only showed 2-3" for NYC, but I'd argue these are outdated

Keep this in mind when looking at Mt. Holly's forecast and snowfall map. Both are only through 7 am Sunday (they only project out 72 hours) and in thier AFD they said, "Given the uncertainty, our latest forecast stuck closely to the NBM," which should mean the 01Z NBM (the AFD came out at 3 am and would've been based on the 01Z NBM) through 7 am Monday, which is the first graphic, which is fairly close to their forecast map.And if they were forecasting for the whole storm, it would've been the 01Z NBM in the 3rd graphic, which is a respectable starting point, IMO, given the still pretty high uncertainty facing them. I'd expect watches to go up at 4 pm, unless we see some unexpected significant model backtracking on snowfall. And there's plenty of room for them to bump totals up should it come to that, looking at their 10% high probability case showing 12-24" - but they also might have the biggest spread from high to low I've ever seen with their 10% low probability case being for <1" for all. Strap in folks.

And the cherry on top might be the AIGFS trend in precip/snow (it's cold enough). And even though I know there's not a lot of love for the AIGFS, the fact that it's arriving at a pretty good snowfall for 95 to the coast, via a totally different model algorithm (AI vs. physics) is encouraging, meaning the GFS solution can't just be some weird data initialization or model physics error. I guess we have to keep tracking, lol.

PTTD (Post-Traumatic Tracking Disorder) Prediction: GFS caves most publicly at 12Z tomorrow, then when nobody is watching at 6Z Saturday all the models jump to the GFS blizzard solution, then everyone celebrates - for about 12 hours - when the NAM sends us all an FU goodbye, by showing that that blizzard is going to become a snow to sleet to rainfest and all the models slowly follow. 2" of snow, then 2" of sleet then 1" of rain to wash it all away. Curtain comes up, NAM bows and waves goodbye.

TWC just had a great set of visuals/animation for both the GFS and Euro runs and also demonstrating what's "steering" all of this, i.e., the big upper level low/trough moving south from Alaska towards off of Seattle, which drives the upper level ridge in the Rockies which drives the upper level trough in the eastern US which our eventual surface low rides along, showing how if the trough is too "flat" the storm heads way SE of the benchmark and we get a whiff or not much (Euro), while if the trough is sharper/deeper it drives that surface low NE-ward towards the benchmark and we get a bomb (GFS). As one might expect, without enough data (and conflicting data) on all of these features (especially that Gulf of Alaska low), the TWC is predicting a bit of a blend of the GFS/Euro, leaning more towards the Euro, but still giving some heavy snow for the coast and less inland, somewhat like the Euro-AIFS, with maybe 3-5" for 95/NW and 5-8" SE of 95 to the coast. Will try to post the video, but for now, here's the pic of their thoughts for the storm: it's not a formal forecast, but their purple is usually 5-8" and dark blue is usually 3-5". It's not a bad "forecast" IMO.

It's an outlier within that group, but it belongs in that group relative to the other 3, as it's much closer to the CMC/AIFS on track and having at least significant snowfall, especially at the coast.

Model Mayhem continues. So, at 0Z, the Euro/UK/ICON all have the surface low move ENE from Cape Hatteras with very robust precip fields (with snow on the NW side of those fields) that are just too far SE to do much for people who live on land, while the GFS/CMC/AIFS/Weathernext2 have surface lows that move ENE from about Norfolk, 100+ miles N or Hatteras, with robust precip fields which are close enough to land to put down a lot of snow at the coast and lesser amounts as one goes inland. Which camp do I believe? No idea, but I will say that the fact that the 0Z Euro ensemble mean is well NW of the Op Euro tells me that the Op Euro has a decent chance of being a bit of a SE outlier and that it should move NW and show more snow. If that were the case, that would tip the balance towards a snowier solution, IMO, since right now, the two best models (Euro-AIFS and Euro-Op) are in different camps.

Bad call. Major improvement vs. 12Z, both in surface low being over 100 miles NW and actually getting 1-3" along 95 and 3-4" towards the NJ coast, vs nada at 12Z. Looks similar to 6Z which people were gushing over.

Like this...

Looks like the 6Z Euro may have been the harbinger for the 12Z comeback. Let's hope the AIFS/Euro look better, like the GFS/CMC/UK do.