JAN 6th Snowfall

I felt it was time this storm deserved its own thread while we save the long range to track the next threat (JAN 11th). For Monday, it once looked like a very promising Mothrazilla or at least a nice 3-6” snowfall. As more time passes, it’s clear the northern side of our forum coverage area - NYC Metro and those N&W - are looking at a nuisance to minor snowfall at best. Meanwhile, the southern portion of our coverage area - DC to SNJ - is looking at a significant event. I believe CNJ is currently the “battleground” that can go either way depending on exact storm track.



A snapshot of the 500mb pattern valid for Sunday shows that the main energy - located over Kansas in this map - is already in a matured upper level low form. This is normally an omen for east coast storm lovers. But check out what is happening along the EC. There is a massive trough (also known as a 50/50 Low) in SE Canada and anomalous ridge in southern Greenland (also known as a -NAO). These features are ALSO normally omens for an east coast winter storm. So what gives? In my opinion, this boils down to 2 problems:

1. Lack of wave length spacing between the main upper level low and the 50/50 trough

2. No phasing with northern stream energy

Without going into too many technicalities, it appears a piece of the Tropospheric PV slid beneath the -NAO ridge and eventually turned into this enormous 50/50 low (the low is sub 950 mb). Ideally, our NAO block would be a bit more north and east, thus allowing the PV / 50-50 to also be more north and east. This would have given heights along the EC a chance to rise and carve out a path for the ULL to travel NE instead of ENE. At some point, the ULL does try to come north as spacing between the two features grows, but once the ULL “feels” the resistance to the north, it transfers its energy to a secondary low in the southern mid-Atlantic.

We will see how the next 24 hours go as far as model runs are concerned. But I’m feeling pretty confident that NYC will be in a C-1” zone while those to the south see a very nice 4-8”+ storm. I’ll probably come out with a snowfall map tomorrow to better illustrate my thoughts.

00Z HRRR is very solid precip expansion. Not trustworthy of course but at least it's solid.

Just going to depend how strong that shunting lobe is in ME IMO as to how far the precip gets. There will be a sharp cutoff but those inside the northern fringe may do better than you think.

For what it’s worth HRRR is a little north with more substantial snow in central NJ.
0z NAM 500mb energy seemed north, but surface output didn’t reflect much change.

3K NAM is also N
The orientation of the confluence is NW to SE and if it ticks N as the 3K NAM and HRRR then these solutions will verify. Well kmow much more by 12Z and observations.

Sill around guys Having lots of up and downs. Snow. Please

I believe this looks good. Keep in mind 30 or 40 miles shift n/s for the good or bad. My guess by what I am seeing in the confluence and faster neutral tilt of the h5 trough this holds or bumps slightly north. Nothing dramatic though the goal posts are set.

Flurries here in Hillsdale NENJ at 27*

Latest 12Z NBMs. If you are in NYC/LI and think a few inches is out of the question, I'd say no. The confluence appears to be just far enough away for precip to expand into southern CT. The second part of the puzzle is instability and if the ULL gets enough of a kick the h7 will to do the trick. So I'd say watch the radar and see how it plays out. If the ULL is weaker then yes c-1" into NYC/LI seems right.

My bar in EPA is 2" but same rule applies to me.

heehaw453 wrote:Latest 12Z NBMs. If you are in NYC/LI and think a few inches is out of the question, I'd say no. The confluence appears to be just far enough away for precip to expand into southern CT. The second part of the puzzle is instability and if the ULL gets enough of a kick the h7 will to do the trick. So I'd say watch the radar and see how it plays out. If the ULL is weaker then yes c-1" into NYC/LI seems right.

My bar in EPA is 2" but same rule applies to me.

This is a pretty realistic map of where I see things netting out. I’ll have my own map out later today.

The clipper that went through Friday night was supposed to a raging blizzard for Newfoundland by now. The center of the surface low is over St Johns and is much further west and warmer than progged. It goes to show nothing is set in stone when it comes to the weather. Some parts of NL will get snow over the higher terrain but the blizzard is a big bust. Let's see how that affects our system...

I feel like this could over-perform a bit in Central NJ from Trenton north to about I-78, but my guess is anything north of there is pushing it.
If I was doing a map it would essentially show the following:
North of I-78: A coating to 1"
From I-195 north to I-78: 1-3"
South of I-195: 3-6" except Cumberland and Cape May counties where 5-10" is possible.

billg315 wrote:I feel like this could over-perform a bit in Central NJ from Trenton north to about I-78, but my guess is anything north of there is pushing it.
If I was doing a map it would essentially show the following:
North of I-78: A coating to 1"
From I-195 north to I-78: 1-3"
South of I-195: 3-6" except Cumberland and Cape May counties where 5-10" is possible.

You read my mind... That's where I'm at too with this.

heehaw453 wrote:

billg315 wrote:I feel like this could over-perform a bit in Central NJ from Trenton north to about I-78, but my guess is anything north of there is pushing it.
If I was doing a map it would essentially show the following:
North of I-78: A coating to 1"
From I-195 north to I-78: 1-3"
South of I-195: 3-6" except Cumberland and Cape May counties where 5-10" is possible.

You read my mind... That's where I'm at too with this.

I think you may be correct

Cannot say this storm will be lacking moisture. Look at fetch right out of the GOM. Again if there is a bit more h7 instability it can surprise.

heehaw453 wrote:Cannot say this storm will be lacking moisture. Look at fetch right out of the GOM. Again if there is a bit more h7 instability it can surprise.

I hope a little more of that moisture than being modeled currently can make it just a bit further north and overcome that confluence.

Storm is pounding snow and sleet from Missouri to the Ohio Valley and Kentucky. Plenty of moisture and really performing at the top end of the forecast snowfall ranges. Hard to believe none of that heavy stuff is making it north of South Jersey. But . . . we've seen it before and the models are pretty consistent. I will say this: I def see South Jersey hitting the higher projected totals in their ranges. Big storm possible down there.

I won’t be releasing a snow map. My call stands at a C-1” for NYC (1” will be hard to come by but ratios and 700mb forcing is working for us). 1-3” for CNJ and 3-6” for SNJ. I wouldn’t be surprised to see very SNJ (closer to Cape May) see reports above 6” but they may run into some mixing.

From DT modeled vs Radar
Precip is much further N but it runs into the dry suppression air over NY/NJ border if not

HRRR has been pretty steady past few runs. Latest 01Z and it's still snowing a bit eastern areas. Definitely could see LI/NYC ~1" as it stands but def more if this h7 energy is stronger than modelled. Cause the moisture is in this system just need to shake it out.

Does not look good for more than 1" along and north of 195. Radar is very poor to boot. Just doesn't have the lift to snow.

Energy getting put through the shredder aka confluence, and getting torn apart.

22.8/20.4
20 dBZ light snow. All surfaces are coated.

At least whatever does fall sticks on contact. I always appreciate those cold surface snows...

Slight close off of the ULL. Height fields are compressed but i've seen worse. The tilt of the trough is slightly positive, but would rather see neutral ATTM.

There's decent bands all the way to Scranton PA into the DE Water Gap so I'd say that is a bit more northward of the precip than modelled.