Carvers Gap

The 12z GFS and GEM....now, that is a much better way to start a suite. Very, very close to being something good. I would think models are getting a handle on that EPO ridge now. Plenty to digest with those two.

Just sifting through teleconnections this morning, the 6z GFS deterministic run is the only model(that I can find) which goes positive with the EPO on the 12th. All other modeling turns the EPO negative - ensembles, AI, determinstics. Could the GFS be right? Certainly. But I have some serious doubts. The real question in my mind which has to be answered(and really cannot be yet) is whether that EPO ridge continues to retrograde into Asia, and whether another subsequent EPO ridge then takes its place. I tend to think it continues to retrograde, but then another EPO ridge reforms as the pattern continues to retrograde even more. That second EPO ridge, in my mind, delivers the worst of the cold per winter toward the end of Jan and beginning of Feb. That does not mean I don't think we see chances w/ the first EPO ridge...I just don't think those details are not worked out in modeling w/ so much being juggled and with us still being about ten days out. It is still entirely possible(probable) that the first EPO ridge sticks, modeling adjusts, and locks in that ridge for 3-4 weeks. I just think a back and forth pattern is more likely as that has been the pattern all winter.

Looking at the CFSv2 LR model this morning, it does indeed keep retrograding the 500 ridge into Asia. It retrogrades the eastern trough into the Mountain West....and then it retrogrades yet another ridge into the West and holds it. If that happens, Larry Cosgrove is going to score the coup, and kudos to him for a great seasonal forecast if it does. He has adamantly held that the end of January and early February will hold the worst of winter, and cautioned patience. I think the ridge getting knocked down out west, reforming....wash, rinse, repeat...is the likely pattern beginning on the 12th. One could make a pretty good case that began on Dec 29th. I think at least one of those cycles will have very cold air in the pattern. A lot of decent winters featured that pattern. Let's see if that is how it unfolds. Either way, this winter has been one of wild swings...I fully expect that to continue.

The good thing about mid January is that AN Canadian air masses often verify as BN or seasonal here. Watch as the air moves south…it often flips to BN. Of note, I didn’t think the surface maps looked terrible at all at this range. The real risk is if the EPO ridge at 500 continues to retrograde and the upcoming trough retrogrades after the 20th…leaving us with only a 7-10 day window. The GEPS ensemble at 0z shows that risk at 300. We need that retrograding pattern to pause or slow once in the right spot. Nina winters really want to put the trough in the Mountain West after January. I am gonna give things a few runs to shake out in terms of whether cold fills the trough or not. If the trough forms and the EPO holds, then cold is less of a concern for me. So with the “what could go wrong” out of the way first. Here are some things to consider. The EPS and Euro at range have struggled to see cold this winter…but generally have been good at 500 - but not infallible. That last comment is generally true for most models not named the Canadian. I have simply stopped using the GFS…It flip flops every run (or every other run) and has too many biases to account for. I like the GEM, but must account for its cold bias. The GFS is going to have to show some skill before I use it past day5. I will discuss its solutions, but it has been bad. As for AI, the jury is still out. The AIFS Euro and ensemble have had some rigor. They look good for the upcoming pattern reshuffle, but they aren’t remarkable in their scoring in my book. The AI GEFS ensemble - I don’t trust it but it looks good. So overall, let’s get this potential pattern inside of day 5. The EPO ridge setting up shop has sped up just a hair overnight. I think the EPO ridge forming is about 48 hours from locking-in as “real” on modeling. It is about 5-6 days out. Once inside of d5, I will “buy” that feature, and that goes for the rest of the features in the map. Until it sets up, I don’t think we are going to really know if the trough fills with cold, if the NAO bridges over, or if the EPO ridge holds long enough to be a force. That is a lot to juggle. I would guess (and could be wrong) that once the EPO forms that cold will fill the eastern trough IF the EPO ridge holds and doesn’t continue retrograding to Asia.

GEFS trends from 0z to 18z. Pretty big moves.

The 12z EPS and GEPS have this as well. AI models can be sketchy for sure - completely unknown. I am not sure they are actually "learning.". I like the EURO AIFS better than the AIGFS(seems not overly rigorous) FWIW. The 18z GEFS continues to trend the rest of the other ensembles w/ the eastern trough. The good thing is the EPO ridge moving into position is almost 7 days out. I will feel a lot more confident once it sets up shop. The NAO has verified as pretty strong...so good sign modeling is handling blocking well. We have definitely tracked patterns which fizzle. Let's hope this isn't one of them. We have also tracked many patterns which eventually verify. Good info on the ENSO and PDO regions - thank you!

The actual EPO is to supposed to build Jan 8-9th. So, that transition is well within ten days. Right now, that ridge building starts at about 180. The transition to that ridge is arueably occurring now.

The 18z AIFS Euro ensemble is pretty much awesome. Big ridge out West, and big trough over the East. Makes sense.

The deterministic GFS over the last four runs has shifted the 500 pattern about 500-1100 miles eastward depending on the feature.

We will see. The GFS is relying on the ridge being over the East and return flow from the Gulf. The trends right now are bit time towards a trough over the East on that model. That model is incrementally caving IMHO. If so, the trend would be much more dry.

The great thing is the 18z GFS seems to have figured out that the trough has to kick out if under an EPO ridge like that. Just wait till 0z, we will have something new! Haha.

The EPO ridge hasn't been delayed as of yet. We lost a couple of cold fronts on the 4th and 8th. This has been moving pretty steadily in time. But we all obviously know the rules. Most of the folks here are pretty solid veterans when it comes to flip flops.

The 18z gfs is gonna give you whiplash. I just want to warn you now. You may need some Advil after this one.

Kind of a theme I am seeing in modeling during the past 24 hours...modeling is struggling w/ the NAO. Duration, strength, and placement are all an issue. I think we score the EPO. We need at least some weak positives over Greenland which would tele connect to cold in the SE and to a block over Yukon and/or Alaska. If you look at wild swings in a model, go look at Greenland...it probably changed at 500. For now, I am riding w/ ensembles and using deterministic models for trends. Once we get Jan 12-13 in range, we "should" (famous last words) see models produce colder solutions. Ok...on to Indiana vs Alabama. I have been looking forward to this one. SEC vs BIG.

This is likely over-done, maybe by a lot. Here is a 30 day Euro Weeklies control map. The Weeklies mean pulls the trough back at the end of January, and I think it relies too much on climatology with that look. Still the mean wasn't overly warm. Even on the mean, the cold punches back during the second week of Feb after a good 10-14 day stretch in January(mean). The control, however, keeps putting the EPO back in the eastern PAC. Again, this is probably too much...but it lets us see something that a washed out mean won't.

TRI will finish +0.7...so, basically normal. Interestingly, TRI had 19 days BN for temps. The 6-day chinook brought temps to normal. There were 9 days were a trace or more of snow were recorded. We had two days where we hit single digits. We had a high of 71 on Christmas. Two days later, the high was 33.

The runs d10-15 have some decent rigor in regards to the long wave 500 pattern. I think where frustrations occur(me included at times) is the details are often just wonky and getting wonkier - see 12z today. My main concern is that some of the solutions make zero sense. Prior to November, the solution might be wrong at that range...but at least it looked plausible. I am a big believer in getting the pattern right, and then let the chips (details) fall where they may. I am cautiously optimistic that we have a chance at a good EPO pattern right when our climatology is the best, beginning around Jan 12-13 for a TBD duration. I think we can use d10-16 maps to get a clue as to that pattern. Sometimes we will see a model lock onto a big storm at that range, and nail it...but generally only w/ big storms. I have seen the GFS nail two strat splits at d16....it has an uncanny ability to model the stratosphere at range, maybe not so much the surface at range.

Ensembles have all run. Generally (exception EPS since it only goes to d15), these are 5day blends of d11-16. In other words, we are taking January 12-17th. I have attached the 12z GEFS and compared it to its 18z run yesterday - flip city. Key notes: -The EPO ridge looks legit. WHERE it sets up is going to be important. -The 12z GEPS is probably the best case, but it is hard not to like the 12z AIFS Euro ensemble w/ that Alaskan block. -Now the 12z EPS is interesting. That is more of a PNA ridge. Likely feedback over Alaska w/ that trough. -12z GEFS is trending considerably towards an eastern trough. It retrogrades the ridge rapidly, leaving only a narrow window for cold. But the trend is your friend with this model. What a great look around 276. -The ridge is retrograding for sure. It remains to be seen whether it stops in the EPO region or continues to retrograde into Asia as Holston correctly noted is a risk. I think it sticks the landing, but that is only a hunch. -Mammoth is getting hammered today as is Los Angeles. There may be rain in the Rose Bowl. -Good trends w/ ensembles at 12z. With deterministic runs all over the map...this is probably the best way to go. -Increasing risk of a stalled frontal boundary. The 12z GEM has it at 240, but as Icy would correctly note...it is 240. The 12z Euro flirts with that as well. That risk is even more apparent on ensembles. I don't see a big snow accumulation bump, but one can easily see the gradient pattern s/ a slight southwest to northeast axis after Jan 10. Thats's all. Oregon has already scored while I right this. Ducks up 13-0...the Ducks are pulling the truck!

Less subtle hint...the 12z GEFS ensemble runs looks good as does the EPS. That energy getting held back in the Southwest w/ a trough over the east. Yeppers!

The 12z GEFS has flipped to an eastern trough. Look at it at 18z last night. Look at it now. @Holston_River_Rambler, thanks for the PDO numbers. It looks like it is trending away from severely negative. We just need it to get near neutral so it isn't default Mountain West trough.

As for the MJO, the CPC plots have it all over the place and all over the COD, but with very low amplitude. I can't find a single plot that gains amplitude. It is very difficult to find even a pattern among the cobwebs of plots. I think Jax's chi image from yesterday is pretty accurate. Six is going to fire-up for a few days, and then fade. There will be mild activity in the 8 region continuously. The signal gets washed out. I did think of this. Can anyone post the daily PDO graph (the one with the running line graph so we can see a trend)? I am going to get my run in for this AM and watch some CFB playoffs. I probably won't post about 12z until the last ensemble runs(EPS) around 2:30. I know some of you think when I don't post...it must have been a bad suite. Nope. Life just get in the way as it should! This is going to be a great football day.

I feel like the 6z AIFS Euro (which just ran) is a pretty good representation of the 0z EURO and GEPS. Temps under that gradually cool to seasonal or BN. It is again worth noting that seasonal temps can get the job done from mid-Jan to mid-Feb, provided that timing is works (meaning not warm-up and rain). But give me that setup - all day long. EPO ridge, AN heights over Greenland and AO regions, trough north(or east of Hawaii), split flow. Trends over the next 2-3 days will be important. For now, decent chance at a good pattern in the aforementioned timeframe.

Now, I do think the following is possible. We have seen it show up on modeling but without overall consistency ->The cold shot around the 12-13th rolls into the Plains and hangs up over the East. It could hang up over the Ohio river valley, the Tenn River valley, the Apps, or even the East coast. If/when it does, an over-running event seems plausible. Beware the cutoff low over the Southwest. They are tricky, tricky critters. On rare occasions, they will simply set-up shop per the deterministic GFS, spin for days, and just burn out. But IMHO, they kick out about 90% of the time. If it were to set up shop there, when it kicks...the trough should still come into the East. Pay me now or pay me later. The good thing I can see on modeling this morning is the EPO ridge is present. That has not changed. When it reaches into Point Barrow, a cutoff OR split flow could develop underneath it. I suspect we eventually see both - a cutoff/bowling ball and split flow. Details twelve days out are going to be sketchy. So, I started looking at individual 6z GEFS ensemble members - it is the ensemble of the worst case deterministic scenario. I am not done yet sifting through the other ensembles. The 6z GEFS is not as warm as I thought it would be. I scroll right on down to Jan13...and then 14th. Remember, those are BN temps during our coldest climatology. A good number of those troughs stall. That tells me the risk for over-running is very high. If I was sitting in middle and western Tenn...I would want to keep an eye on this, even E TN. I can't get individual 500 height panels for the US, so I resort to looking at the temp maps above. Below is the 500 mean map for the hour above. The individual members tell a different story. Many of them must have kicked the trough eastward as the SER is squashed on roughly 2/3 depending on your definition of "squashed." Many of those cold fronts stall somewhere over the East. Knowing that SW bias is possibly in play, we take that 500 map and run with it. The EPO ridge has blocking over the top. Below is the 12z trend map for Jan 12. It looks like that for the rest of the run which implies the ensemble is correcting eastward with the trough.

If you look at the 6z GEFS at 500, you can see a possible feedback loop start at 276....seems not realistic at all.