SnowGoose69

Pretty crazy how both the events at 144 and 210 in N AL and N GA are basically both rain due to lack of cold air

Ensemble wise nothing much has changed. The pac change is still showing but both the EPS and the GEFS are showing signs the AO and NAO could move towards neutral by day 15. Given we are in a La Niña that’s entirely possible as mid January approaches. At the same time though ensembles have been trying to show La Niña type pattern shifts on and off at the end of the long range since late November and have continually failed. Even the weeklies are trying to show it somewhat at week 4. It’s possible the true La Niña change never happens because so far every time it pops on models it never comes

I presented on that storm as a research paper and it was truly a cruel evolution. Almost nobody remembers this but the shortwave or upper disturbance which produced the 12/30 storm was responsible for acting as a kicker to a previous shortwave over the southern US that was supposed to phase on 12-28 or 12-29 with a strong Great Lakes shortwave somewhere in the TN Valley or MA. Instead the 12-30 eventual producing disturbance booted that Gulf one out to sea and the big one didn’t happen. The storm that was initially shown on models 4-5-6 days out for 12-28-29 was a monster that would have hit everyone hard up the coast

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

I think it’s classified on a Niña by some and not others. Same as 96-97 and 89-90 are classified as neutral by some and weak Niña by others. 17-18 is a better example of a La Niña winter with several progressive suppressed deep southern snow events

It is amazing to me how much the GFS Op continues to struggle with this pattern. It just wants to cut and build the southeast ridge on most runs beyond day 7-8. The difference in the 12Z runs today for the Euro and GFS day 8-10 is just astounding and it’s been several consecutive runs more or less with that idea

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

The GFS has been continuing to have issues of wanting to cut things and pump the SER up until day 8-10. The CMC and Euro have been backing off and will probably verify more accurate

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

81-82 here in NY. I don't know if it was west based but it was negative most of the winter and the winter had very little snow.

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

Many think that. Similar to how in the fall several years back that insane remnant west pac tropical slammed into Alaska and brought an absurd cold spell in November and that was basically it for the winter. The remainder of that winter was fairly mild although I think snow wise it was not awful. I cannot recall year that was but ensembles Day 10-16 were very optimistic for a pattern change til that Alaskan situation too place. It seems to an extent an SSW always screws someone because ultimately the process impacts pattern progression to a degree in the whole hemisphere north of 35N. The January 2012 SSW no question screwed NOAM. Models seemed to be hinting a -NAO would develop but the SSW ultimately shifted the pattern to one that favored Europe

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

Just have to see now if it keeps getting kicked. The last 24-36 hours all 3 ensembles more or less show 1/8-1/12 the transition to the -EPO or +PNA look. I think I want to see that come inside 240 before I believe it. No idea either how the SSW which does look legit at this time impacts this. Obviously the major results won't transpire til mid or late Jan but we saw 2 winters ago how the warming process basically effed over what was going to be a good pattern shift for the East.

3/4-94 I think. Big elevation snow event and interior event while coast got rain. The pattern more or less went 2011 on the northeast and MA after 2-20 in 1994 though it did get cold again for a week or two from 3/15-3/30 but overall I always point to 94 04 and 11 as being years where pretty much after early to mid February winter ended. In 04 there was a return again in mid to late March much like 94. 2011 it truly ended and never came back

They also don’t realize that are plenty of storms where a -NAO can actually hurt you. It’s not common but there are mostly definitely cases of storms that produced rain from DCA-BOS where if the NAO was positive might have been all snow events. You have to dig in to find them but they’re there. To an extent 12-25-02 is a storm that if the setup over the Atlantic was less favorable the storm might have been snowier near the coast and that wasn’t a raging negative NAO either

That’s the same pattern more or less as 93-94 though I believe 93-94 the negative heights by Greenland didn’t extend over the pole so we had somewhat of a phony or weak -AO most of the winter. That winter wasn’t particularly good in the MA though. Had the NAO been negative maybe it would have been different but as DT has pointed out before the 93-94 and 14-15 predominant winter patterns it’s next to impossible to have a -NAO

I think most would take the 384 18Z GEFS pattern

We are sort of due for a good one. Last good one was what? January 2012? It didn’t impact us but feels like ages since a fairly effective SSW occurred.