Carvers Gap

The 6z GFS. That'll work. So will the 0z.

The 18z AI EPS. Some big dogs in there. Two separate storms. Windows are 14-15th and the 20th.

The 18z GEFS and AI GEFS are AIFS Euro are COLD in the window that we need them to be. Keep the STJ cranked, and let's roll.

Basically, the 18z GFS traps a piece of the TPV under HL blocking. It just sits and spins while locked over central Canada. This is what ensembles might not be able to see. It kind of looks like LR ensembles w/ a SER. But...that SER is minor as it is getting lifted into place by the strong BN heights over Canada. The HUGE plus on this run....storm track is right over our forum area w/ repetitive winter events.

After 200, the juiced STJ is firing right into an inbound Arctic air mass.

We got JB talking about a d15 warmup. Meanwhile, this GFS run is going to have it snowing in Cuba.

An outlier the 18z GFS may be...it is about to send it.

Haha. That is just an insane HL blocking run by the 18z GFS. It is either the beginning of a trend(and I have seen more NAO recently on modeling in this time frame) or this is a toss. It is a beautiful pattern, but for sure an outlier.

The 18z GFS continues the trend of bringing light snow to the region around Jan 15. Miraculously, a huge NAO is in place.

Great discussion in here this afternoon. I enjoyed reading all of that - even if it isn't all snow!

The interesting thing about La Nina...there are a few analogs which aren't dry during winter. I think @John1122 has posted those thoughts prior. In fact, they can produce flooding rains at times. I don't think we are out of La Nina quite yet. That said...there was worry about Canada losing its cold. The 12z Euro(yes, it is at the end of its run, but has support from its ensemble and across some other models) had this at the end of its run. Let's see if the 12z CFSv2 can get on a run. If flipped cold for Jan 21-31. I probably is a blip, but the image below kind of fits where I think we are going. The coldest air is going to push into the Canadian Prairie and refuse to budge. I am sure the West will get its fair share...but one good cutter, and any warm-up would go poof! This also fits exactly what LC's analogs have shown for late winter. Can you imagine what the Lower 48 would look like w/ a strong amplification in either of the blocking areas would produce? The SER will fight, but w/ that air mass as a plausible option...we may need a little SER.

1). The 12z Euro appears to have some chances as well w/ multiple vortices and energy climbing the EC. That pattern is loaded w/ chances every few days. 2) If you watch the end of that run, the western ridge rotates rapidly west through the Aleutians. It moves so rapidly, it might well allow the EPO to rebuild. If you look at the end of the GFS run, it sticks a trough out West. But the ridge in the Aleutians moves so quickly that you can almost see the ridge sliding underneath the western trough, ie the eastern trough is already retrograding. 3) I don't lose a ton of sleep at this time of year. What I "think" is going to happen is part of the TPV is going to crash through central Canada and almost force a trough to stick in the center of the continent vs out West. The SER will fight it, but cold will push against it as it pinwheels around that trough IMHO. I think the 12z AI GFS is the extreme eastward version of that look. I think the Euro is about right...I might nudge it a bit west - speaking of 300hrs +. 4) Again, I remain optimistic that the Jan11-21st time frame is a good one for wintry weather. Then, we get a TBD break(could be quick). Then we repeat the same cycle. Again....One variation(instead of a western trough) I think has some merit is the 500 TPV rotates int0 central Canada on its throne, and makes everything work around it. Very blocky looking pattern.

The 12z GEM has a storm along the coast during the 14-15th and a northern vortex crashing in. Close miss but still some snow. Good overall pattern though. As for Bam, I generally have steered clear of that site most winters....flip-flop city but some really good content at times. Right now, the MJO seems decoupled from the NA weather pattern to some extent (certainly some influence). I think the window from the 11th-21st(maybe a little longer) is a good window. Then, it looks like another ridge will retrograde through the East. The positive from the GFS is that it RAPIDLY moves the Alaskan ridge through the Aleutians into Asia. The faster that goes, the faster that we see the ridge develop in the West again. February looks like it will have another deep trough develop between Feb1-10. Remember, I am big on finding windows for winter precip, and then watching details as that window draws closer. I do think there is a chance the ridge locks out West, but maybe a 40% chance on that.

Man, the 12z GFS is just barely missing on some decent chances. By 258 and just barely in fantasy land, the 12z GFS looks very similar to its AI counterpart. Jan 17 is kind of a timeframe I have circled when the base of the trough flattens out, and allows for storms to slide across.

The 12z ICON buckled the jet further west than the 12z GFS. I wouldn't be surprised to actually see a cutter in that time frame...that is how "off" that run was Jan14-15 on the 12z GFS.

I will say the 12z GFS still rotates a lot of energy at 500 through the northern stream. It barely missed a phases right there w/ the southern stream. The southern stream energy was just slightly ahead. I wonder if that is going to end up being a storm?

Looks like we are going to see this cycle back through one more time w/ the retrograding ridge...might be two more times. I think February, w/ at least one pause, could be an interesting month. Did you see the end of the 12z AI GFS...that is a HUGE trough. I suspect we see a ridge pop over the East at that time, but the AI GFS isn't on board with w that idea quite yet. That trough is how record lows are broken. Huge grains of salt at this range. 12z GFS looks pretty dry so far. The trough is slightly too far to the East.

The 18z GFS is a really good run. It isn't the first model to have a great run during the last 48 hours. Hopefully, we continue to see those runs get more numerous. The 18z AIFS Euro is also good. Essentially, we just want to see a cold trough in place w/ buckles/ripples emanating along the STJ or polar jet. I am not really looking at details quite yet...just for a tendency to grab a gradient pattern which buckles a bit. So far, the pattern looks reasonably active. We have tracked this trough since probably before Christmas(or right at). It would be awesome to have some in the forum score from tracking so far out.

Before there were all of these beautiful weather maps, we used to simply use 500 Geopotential height maps. I don't even think we had anomalies when all of this was first on the internet. I just used NOGAPS(US NAVY) and eyeballed it. I can say...this is a pretty good look on the EPS. And isn't bad for several days prior to or after this screenshot - it looks even better after this. But when you are looking for winter storms at our latitude, this is what you look for. So, we have moved on from tracking a ridge flipping back West to actually tracking timeframes during a window which looks good.

In reading JB today, he is less optimistic after the 20th(roughly 20th-end of the month). I think relying too heavily on the MJO has been a problem all winter, and continues to cook forecasts which rely to heavily on it. I don't see clear trends(yet) that it has impacted NA weather meaningfully. I do think GaWx's phase 6 discussion is interesting and has merit. What I do see is a retrograding ridge which should(and have I said this prior? yes) continue to retrograde into Asia. As the ridge hits the Aleutians, that teleconnects to another eastern ridge. Then, we repeat that same cycle all over again. I don't attribute that to the MJO. It is a retrograding pattern with a mind of its own at this point. So, I do think there will be a ridge(and I have already said this) which forms in the East after the 20th and then retrogrades westward again. But I am still not sold that actually occurs. Deterministic and ensembles are having trouble moving that EPO ridge. That is not an easy pattern to break down. Deterministic models at 12z look pretty decent today....understatement BTW. As I have noted often, the 95-96' progression seems pretty likely to me. Snow? I doubt we see two blizzards! But at 500 it looks remarkably similar. JB is just mad, because his seasonal forecast didn't account for the inevitable southeast ridging produced by La Nina. 95-96 featured a window for winter weather, a warm-up, and then it repeated. That seems plausible to me, and fits the winter pattern. But if I have to choose a horse to ride, LC has the hot hand. I think by the end of February, many (not all) will feel like they have had winter.

The 12z Euro is even better. I am optimistic at this point that we see winter weather in the forum area. The pattern fits it. Deterministic runs are beginning to throw us a bone or two. I think we will see some small northern stream vortices clip northern areas first, and then we watch the timeframe around the 20th and after for a big dog, and again...also the 14-15th for maybe something. All of that fits climatology. It is growing more likely with each passing day that LC has nailed this seasonal forecast.

Skimming through modeling this morning, it looks like the window around Jan 20th and after looks best for snow with a window Jan14-15 still in play per the 12z GFS. The 12z AI GFS is wall to wall chances beginning next Sunday. The 12z CMC has upslope chances on Sunday. Both runs have not been completed.

Really great runs by the 18z GFS and AIGFS. The good thing is that there are now a few windows of winter weather opportunity during prime climatology. And so far(famous last words)...the 500 pattern has not been can kicked. The EPO ridge is set to arrive on Jan 8th-9th. We wait all year to track in this time frame. Some years, we aren't able to track in mid-late January at all. Take advantage of it when and if you have the time. For those of us who have patiently tracked this, I hope our patience is rewarded. Kind of a fun thing to track a pattern for several weeks, have the 500 pattern verify, and then maybe get 1-2 winter events with that. Doesn't always work out that way, but it is rewarding when it does. As for details, I am cautiously optimistic that we will see winter weather return w/ the eastern trough. Been burned too many times to ever throw around absolutes in this hobby. But for now, it looks good.

Again, I want to remind folks to beware of ensemble means at d10+. There are a very few warm solutions which are skewing the mean. If there was a median, it would almost assuredly be cold at 12z. I like this look at 500. The PV at 500 is over NA and not Asia. Some may correctly point out that is 3336...Yes, it is. However, the vortex is almost in place by about 272 on this side of the pole. The 12z GEFS is far more aggressive than this. I chose the least aggressive. But for fun, switch your model to Northern Hemisphere view and 500 Geopotential height...and watch the cold develop over NA. IF this occurs, ensembles are highly likely to be too warm after 300.

At 500 and the surface, the 12z GFS, CMC, and Euro are remarkably in sync for the duration of their runs through 360 - western ridge and eastern trough w/ vortices diving into the eastern trough and a somewhat active STJ(differences exist w/ it).