Carvers Gap

12z is a bit more interesting in terms of winter wx. The GFS is again stronger with the Jan2 cold front. Both the the GEM and GFS hint at WAA right after.

Interesting quote from MammothSnowman after a very rough start to their season(uncharacteristically no snow in much of the Sierra Nevada)... Storm Summary as of Christmas afternoon, the snow study site showed 4.66 inches of water content at 6 AM, and at 2:30 PM, the gauge is at 6.07 inches with 14.7 inches of new snow today. Snowfall Storm Total amounts at the snow study site are an estimated 65 inches. Adding the 30% adjustment for the Top, the Powder Fields of Mammoth would now have received over 79.5 inches of fresh snow. The Christmas Miracle Storm has come through with tons of base snow, and the season is saved at the last bell. Amazing…

@John1122, Mammoth is getting absolutely hammered right about now. Those cam stills are impressive.

Last post for a bit...any time we start seeing big highs in Canada on modeling, that has been a good signal for winter weather in our area. 17-18 would be the exception.

I agree. Nice window. The end of January and early February has a similar signal. I really want to see if the 12z GEM moderates its temps for Jan 2 or if other models move colder. The 6z Euro trended colder as did several members of the ensemble, but ended before it got here. Not sure I want to see that entire air mass on Jan 2nd. I think our best bet is for the Canadian Rockies cold to come out in pieces and catch the STJ if it can get more active. I think the GEM has the right idea with the cold front on January 2nd, but also is suffering from feedback in the form of too much cold. But any air mass which is that cold could very well have snow with it. I will guess moderation for Jan 2, but still cold. That leaves the door open for Jan 6-10 to have a storm IMHO.

The 6z run has a 1065 over the Yukon on Jan 9. And that run of the GFS...sends it.

Yeah, I missed that. Fun find. Definitely feedback IMHO, but IMPRESSIVE that any model could actually find a way to that outcome. I just don't understand why we are seeing so much of that(feedback) this winter. WxBell graphics had to resort to white in order to illustrate that....they ran out of colors.

All 3 global ensembles breakdown the Aleutian high. The 0z GEPS and 6z GEFS take it out just after 300. The 0z EPS wipes it out just after 200. All three end up with some version of blocking around Greenland, a ridge out West or the Eastern Pac, cold in Alaska, and BN temps and/or heights over the SE which is fed by an anomalously cold Yukon air mass. Sort of looks like the same pattern we had to start December? Right now, the potential cold pattern looks dry. I can't disagree with it. However, to quote a met in the ENSO thread...it is very unlikely modeling can see details this far out(referencing d+1-) regarding storms. Generally, I think our forum scores best when we have cold in place, or it is just lurking in the Plains. One would think the entire Canadian Rockies cold air mass kicks eastward at some point. It has during recent winters. There are hints of that in modeling - some sooner and some later. Lastly, LR ext modeling(weeklies) hints that the strongest cold shot will be near the end of January and into early February. I simply don't know at this range, but it is worth keeping an eye on.

It may seem a bit quiet in here, and thus mean overnight runs were not good. Nope, they were good, especially regarding cold. The 6z GFS produced a run with the January 2 cold front, and the 6z Euro was headed that way. Does it get as cold as the 0z GEM which has been leading the way in finding cold fronts? Probably not - I hope not. But the GEM (let's see how 12z looks at lunch) may be on its way to scoring another coup. It identified the Dec 29-30th front first as well. That may mean we have a useful instrument going forward in identifying cold fronts - just add some degrees back. The 0z Euro looked really good at 500.

IF the NAO were to hold w/ the 18z GFS look in the Pacific late in that run....now, that would be fun. What an EPO ridge on that run. I have no idea if the flip flopping is over(prob not), but what a reversal after d8 when compared to 12z for the GFS. Still plenty of uncertainty, but trends have been decent today. I may be back later. If not, I hope all of you have had a great Christmas w/ still more hours to enjoy. I have to admit, I enjoyed running in the 50 degree temps this morning - don't think bad of me! Haha.

The 18z is a jailbreak pattern after 300 in fantasy land. It pretty much mirrors the GEM runs, but about a week later. I think modeling just isn't sure which cold front to send the cold with...we noted that yesterday or this morning. Good trends, but a ways to go.

The 18z GFS continues on its own solution path. But it kind of still manages to get to where other models are by about Jan 6. For those who are enjoying Alaska extreme runs...That is a -85.4 reading. And the EPO ridge pops....all of that is headed for the Canadian Prairies. It modifies quickly as it heads south and east...but that is the ticket if you want winter.

Here is another nugget from the 18z ICON. It isn't a December map, but extrapolate...LOL. addendum: The way that run looked. It had the PNA locked into the West w/ the AO and NAO negative. If the GFS can back its trough up just a little, it gets here IMHO. At 18z it isn't there, but it trended that way again at 500.

I really am interested in the Jan 2nd timeframe. If we can hit that in a reloading pattern, that would be good IMHO. Here are ensemble members for major ensembles. Only the GEFS is void. I wouldn't list it as an outlier quite yet, but with the 12z GFS trends...probably it is. Pretty nice uptick since yesterday. In the unlikely chance the GEM hits a coup(along with its ensemble), that would be an impressive cold air regime which pinwheels in. Still plenty of uncertainty as of yet.

Texas or sure needs a MUCH better Pacific. We just need a serviceable Pacific w/ the NAO in place. I think climatology eventually wins with this setup. For mountain areas, climatology could win bigly. Foothills areas....TBD. Middle and western areas...I would say sliders are the best opportunity w/ the NAO. But we'll see. You all usually find a way to score w/ Nina winters and ample cold. Even souther areas of the forum(northern regions of the Gulf states have a shot).

Here is the 30day map. There are several good time frames in here which are washed out - day 7 increments have those. Really, there is a window between, Jan6-20. The graphic above(from me) makes it look like we have to wait until week 3. No, the good window is now on today's 12z EPS run(not the Weeklies). I wanted to add this one so you all can see where the NAO is centered...right over the Davis Straits. @Golf757075, there it is. Let's see if it verifies. There is another window to start February. Now, that is shades of 95-96 IMHO. To get off to a good start, we need a cold front on Jan 2 and/or 5th to score w/ getting cold into the forum area. Cold in place almost always is our best way forward. I kind of wanted to make sure the past day or two of weeklies runs weren't one-offs...before commenting. But still, proceed at your own risk. Models have been absolutely treacherous at this range.

@John1122, I am not sure I trust the Euro Weeklies right now, but as @GaWxnoted...pretty big changes in the week 3-5 range. Basically, the pattern just is wash...rinse...repeat. NAO/Aleutian high -> NAO/+PNA...over and over. This is week 3, and would be awesome to have for peak climatology.

For really the first time in a few weeks, ensembles are pretty bullish with the exception of the GFS/GEFS which are just worlds apart from any other model - even its own AI model. They are outliers. In my book, though, the deterministic models have led the way. Something is not right w/ wx modeling right now. I maybe can remember one winter where modeling was completely blind to cold fronts. The GEM, with its cold bias, is useful right now, because it exaggerates the pattern enough to find them. Sometimes when graphics are exaggerated (like increasing exposure on a camera), one can spot details which can't be spotted otherwise. In this case, the GEM is spotting cold fronts in a similar manner. Just subtract the cold bias. My guess is the mistakes are occurring with the MJO region which has no real clear signal, the extreme cold in Canada, the NAO stepping onto the scene, and was the Aleutian high over estimated in terms of staying power? Throw in some atmospheric river stuff...and it is understandable that struggles are occurring. But this deal where the GFS can't even see a cold front past d7 is really weird - something has been tweaked in the model IMHO. It is just missing wildly right now...unless the pattern is warm.

The trend of models being blind to cold fronts (until a week out) appears to be continuing. Just so very odd.

I mean the Jan 2 trends are pretty stark. Models don’t have the below zero axis of the cold air mass on the GEM, but they have completely erased positive temp anomalies at that time and shifted SW with the cold towards the Ohio and Tennessee Valley regions.

12z trends are towards the GEM…to be clear not to that extreme, but a cold eastern US.

The 12z ICON has moved to the 0z GEM at 500. Let's see if the 12z GEM actually holds to the 0z GEM!

As for Mammoth...their webcams are awesome. I dropped a link for their cams on the mountain. Just another world for snow rates. The cams range from 8000' to 11000'. We stayed at 9000' this past summer when we were out there. It is crazy to see everything buried now. The ground was bare two days ago - they had almost no snow below 9500'. Very late season for them. (Some Colorado resorts further east still have bare ground.) If they didn't get this storm, I am not sure when they get another window like this. But...it is easy to see how the Donner party got caught. People were hiking up until two days ago in the 10,000' range...today, you would be stuck. I mean the ground in the Sierra Nevada was bare. They have been super warm while the East has been cold. The 6z AIGEFS lent a bit of support to the 0z GEM - it doubled its colder members since 0z. We probably are going to have to look at ensemble members in order to sort the cold fronts out for early January. The mean will continue to be skewed until the last minute I think. https://www.mammothmountain.com/on-the-mountain/mammoth-webcam/woolly-cam

The GFS IMHO continues to be a bit of an outlier as it forms and breaks down the NAO rapidly. I can’t find another model doing that. I can’t remember which model handles the NAO better. Who know? It might be right. The GEM is another adamant outlier outlier with its solution. I would guess it continues to trend towards a NE cold shot vs Deep South. But it has a good habit of finding cold fronts, albeit too intense with its solutions. The Euro looks like good middle ground - for now. I would not be surprised to see models trend colder after a warming trend over night. We have entered that 5-7 day window where things get lost. Also, it would not be surprising if models were simply too quick with the cold. I am noticing a trend to send the cold on Jan 5 instead of 2nd….even the 8th. Models are bouncing between those dates. Remember in late November that modeling had the cold, lost it, and then brought it back. I would not be surprised if we see something similar now. Been kind of a weird year with model biases and feedback. With the exception of the GFS, other modeling has the NAO. So, a great sign that it is still present. I think it is the Euro which eliminates the Aleutian high late in its run. Either way, Merry Christmas to all of you! Have a great day!!!

LOL. That is a great line. I always forget about mountain torque events in Asia. I am assuming this is good or us?