SnowGoose69

Up until recently there were hardly any major events with a positive NAO. Certainly there were some big overrunning type storms or southwest flow events but these borderline KU events with deep coastal lows occurring with positive NAOs is mostly something that’s only occurred in the last decade

Not really. The PAC was really good otherwise, even for the earlier December events which I think two changed to rain at the coast. The pattern out west broke down for a while there in mid to late December.

Even the Para has been trying to crank ridges in the east past day 7 on many of its runs. It hasn’t been as awful as the GFS but it’s still doing it. Just look at the difference in the GFS Op runs today at 12Z compared to the Euro at Day 6-10. One has 534 thicknesses to Atlanta the other has highs of 65 in DC

Yeah it was a good example of terrible pacific good Atlantic with a snow event. I always show that event as an example of what a -NAO does

The GFS, especially the Op but definitely a percentage of the ensembles still want to keep cutting things out to 240. It’s pretty evident the CMC and Euro Ops and most of the ensembles aren’t doing that

Even if we do it might not matter much of the NAO stays strongly negative along with the AO. It would probably still be a pattern where something could occur

Honestly the weeklies appeared iffy with the EPO...at least from the image I saw in the MA forum there appeared to be hints of smoothing indicating some appearance there could still be low heights in BC/GOA etc. As I said earlier today though, the deeper we go into winter I don't care if the EPO is +10 if the NAO is west based and -4 there will be significant snow chances and relative cold in the East. The NAO matters more and more as we go on and while the Pac does not matter less it tends to get muted more easily by a W based -NAO in Jan/Feb/Mar than Dec

It would not be the GFS if it did not lose a southern stream storm at some point in the medium range

True but I have to say I don’t recall a case in the last 22-23 years where I’ve really followed these indices where anything like this has happened before. Part of it is that December is probably the only month in winter where this type of alignment can occur and the pattern and air mass nature could suck this much, so you have narrow period to a degree where the stars can align. I think even in early to mid March this set of indices with a bad EPO would produce a markedly colder pattern than this. I think alone the W ATL SSTs being colder in March would likely cause less ridge bridging between that SER and the NAO ridge than we keep seeing models trying to spit out. Whether or not that comes to fruition I don’t know but they’ve been trying to show it

This is a classic pattern where a snow event will appear out of nowhere. It’s a combo of there being enough cold air around and the models really sucking badly beyond day 5 recently

Its not unusual at all to see a fairly crappy pattern in December and sometimes in early Jan with the AO/NAO negative. It becomes increasingly difficult on an exponential level for that to happen though once you progressive through January

The Op GFS had another “glorious” run at 12Z. It basically just continually repeats the same thing over and over Day 7-16 which is almost certainly wrong but it’s funny how many torch cutter Op runs it’s continued to have while the ensembles argue for something totally different

The Pacific is really bad til 1/1 which is partly why but models, especially Op runs can show patterns at day 7-10-14 that don’t look anything like the indices and ultimately correct as you get in closer. We saw that in recent winters where MJO was raging phase 5 and the AO positive and the GFS of Euro Op run at D10 thinks you’ll have -20 850s with a trof in the east

I think the GFS as far as areas down by NYC/coastal SNE not changing precip over is a result of the unusual nature of the setup where the surface low basically passes SE of everyone with a strong high to the north but the 700/850 lows are displaced NW. Usually the GFS will torch the BL in this type of scenario and show rain but because of that high pressure it is not even doing that so its more wrong than it even normally would be

The GFS has come a long way. Although I believe it’s too far SE and it’s not grasping upper or mid dynamics and hence QPF it was always reasonably close to other global guidance from 5-6-7 days out. As recently as 5 years ago that never would have happened

Sometimes you almost just have to go with history on these things if you look at the EPS/NAM solution it would indicate New York City goes snow-rain-snow. When have we ever seen a storm with this type of set up do that in New York City? Either they stay all snow or they go snow to rain and stay rain and does anyone think that this could stay far enough west where they flipped to rain and that’s it? I just don’t see it given the pattern so I’m leaning in the direction of something splitting the difference of the GEFS EPS. I feel confident both models are too far west and east respectively

Technically the Euro is going to get tomorrow correct it seems while other models were too far NW so it won’t be consecutive misses if it ends up too far NW Wednesday and Thursday

Yeah it finally joined the party. The RGEM tried to as well but didn’t get there

It’s damn tough to get a major snow event within 20 miles of the coast in NJ this early in the year barring a perfect setup. A 030-040 wind there is off 50 degree water. Even for JFK it’s a night and day difference as the same wind for them is primarily off land outside of a brief trek over LI sound

I don't think much from there. Keep in mind the ptype on the GFS for you is probably wrong. Many places would hold the ageo component there and not flip on that track. Some are playing that if the PNA weakens this cuts more. I don't think there is much room for that. My hunch is if this ends up being warmer/west than this its probably because the system got delayed 18-24 hours allowing the high to further slip east

I am somewhat wary of Monday being flat because the WRN NATL setup. Those sort of systems in recent winters when we have the upper air pattern we have in place Sun-Mon have almost always been west/amped of what the 48-60 hour guidance has suggested. The CMC has been running somewhat well lately though.

The EPS does not like that event either. The CMC has been pretty consistent in saying that one is a dud. The Euro joined it the last 2 runs. A weaker Monday is probably better for SNE Wednesday...well at least for places that are not SE

If the Euro is correct on starting to flatten the Monday wave its more likely the Wednesday one could be issues for places in the MA. The tendency for days has been ensemble members and Op runs which are flat Monday are more tucked Wednesday or warmer

Given the air mass in place and the setup this thing can basically track just east of Montauk and the only places that would mix would be the Islands and maybe parts of the Cape

CMC was only model to go flatter for Monday lol