Carvers Gap

12z GFS is a complete pattern reversal. Its ensemble, while not a pattern reversal, is winter.

Thanks, man. Hope you and your family are doing well. Is Nina expected to last through winter or move to neutral?

The 0z European control lifts out the Aleutian's high, and temporarily reverses the pattern downstream. We have seen that look on a few recent GFS runs, notably the most recent 6z.

So something to watch is the breakdown and/or weakening of the Aleutian high. The EPS is very aggressive with this. I ned to see a couple of more runs before I give that look credence. However, the GEPS is similar. The reason the GEFS is an outlier this morning among the big three global ensembles is that it is slower to weaken the high. However, the trend across the board was to weaken the Aleutian high overnight(in the long range). Let's watch and see if this is a trend. This is the time of year when the EPS begins to rule the roost. So trends on it must be taken into account. Could just have been a blip due to data input or could be the beginning of a trend. Just don't know right now. One other thing to watch, and the Euro Weeklies had this yesterday, is for the cold to push under the SER. That is sometimes a mistake by modeling to depict that, but it can happen during January as climatology(favors stronger cold across the northern hemisphere) supports colder air masses which can push....

That is an El Nino signal right, and strong at that?

Oddly this AM, the warm biased EPS has a nice set-up from the 3rd forward with a ridge rolling through during that time. Will wait and see if it holds at 12z before discussing further. Right now we have the EPS/GEPS with colder solutions after the 2nd with a ridge rolling through after the cold shot. That window around the 3rd has some potential though the window is tight.

We get back to what Typhoon Tip talked about several years ago which is the SST gradient between an ENSO event and surrounding waters. The gradient has to be sharp for the analogs to work. Additionally we have not seen a lot of trips through 8-1-2 with the MJO either due to the IO or other reasons. I would probably disagree that we have seen a true -NAO show(Davis Straits) up at the proper time until last year. Having a -NAO that lasts most of the winter is a rare thing. I definitely agree that the trough tucked into the West(under an EPO ridge) has been a strong commonality for roughly four years or so - regardless of the wx pattern. My personal opinion is lack of SST gradient and convection in MJO zones which less than advantageous. That said, what we have seen IMBY are quick starts to winter which fade. This year, that cold came in November. The trend here has been early snows, even as early as Halloween. Last year, even with a similar pattern as this year, we still managed a historic ice/snow storm over the forum area. The other thing this winter is just how cold Canada is... I suspect that we see a bit of a scaled reset of Pac SSTs after this La Nina. We have had good winters after La Nina cycles. Why? Water cools and the gradient for the Nina which is surely to arrive next has a better gradient.

Going to hit the sack and will end with this, there is a lot of precip running that boundary after the 30th. If it manages to get colder, that event has low percentage chance of being a frozen event.

0z GFS is a strung out mess with vortices all over the place....like I said, be ready the next run will change.

This GFS run will revert back to a strong Aleutian high. Trough may rotate through after the cold front on the 3rd. Feature that seems kind of new is the vortex over HB which is spinning cold air southward. That cold work. Let's see how that works in future runs. Been there for several, but is seemingly more pronounced with each run.

By 210, the Aleutian high is back....the question is will it rotate eastward as the trough digs SE. If so, and EPO would pop.

At 204, it appears the cold front has sped up a bit...let's see if it makes it all of the way through.

Just because it is a slow night....will talk the 0z GFS By 189, there is a continue trend of disrupting the Aleutian high. Trough would appear to be headed eastward...we'll see if we don't get a cutter first.

That pattern I just posted looks remarkably similar to LR modeling today...and also to Feb 20'. One was a nada and one was a La Nina. One was a dud and the other was historic. @John1122, very interesting about LA and great post. I have always considered storms coming in at the latitude of LA a good thing. That has not held true so far. I have held to the rule of thumb that storms that enter the west at a specific latitude normal exit on the east at a similar latitude. Not always true, but wonder at some point if that works in our favor.

Yeah, I kind of stumbled into the Feb 20 thread. Pattern looks very nada right now...similar to that. Here is last year's pattern that ran up to the big storm.

Not sure how I got into the Feb 20 thread! LOL. Last year's GEFS(about two weeks prior to the winter/ice storm) do indeed look almost identical to LR maps right now. Correct link is above. Thanks to @Holston_River_Ramblerfor posting those gifs. They are a great historical tool.

19-20'...What was the ENSO state that year?

Ah, yes. Thanks. Grabbed the wrong one. Here is the set of Weeklies running up to the outbreak last February. Still, lots of similarities to now.

Update: This is the wrong link. Correct link to the weeklies is below. Unreal the similarities. Thought this was kind of fun. This is what the Weeklies had for the pattern that ran-up to the crippling Arctic outbreak/over-running event last year during mid-February. @Holston_River_Rambler, just needed your map - not picking on you in the least. Take a look at Holston's bleaklies thread. Indeed, they looked bleak. Two and a half weeks later, the power was out in the western areas of the forum.

Trough eventually lifts out, but I am starting to wonder if we might be seeing the initial seeds planted for a pattern reset. GFS is likely early, but it has hammered the Aleutian ridge during several recent runs. Not saying the reset will be any better. The LR result of that is the PV lifts northward, and we are left with zonal. Nor worried, that will very likely not be the same next run.

LOL. That is an awesome run. TPV gets trapped and the dam breaks.

Impressive, impressive run of the 18z GFS. I also didn't think the Euro Weeklies looked half bad. Its control looks strikingly similar to the current GFS.

294 on the GFS is how this gets done...just an example and not the gospel. This is the second straight run with something similar.

The 18z GEFS is how winter gets unleashed for a time. Impressive trough.

Interestingly, the 18z GFS is sort of doubling down on the same deal. It is hammering the Aleutian high(edit).