psuhoffman

Definitely but I guess that part I just took for granted since the -NAO is there across all guidance. The difference is the GEPS/EPS lost the EPO ridge and develops a flat pac ridge.

Yes. It all comes down to that. The GEPS is fully on the EPS side now. Both lose the EPO ridge and the pac jet gets directed right into the CONUS. It’s all down to that one feature because everything else is identical across guidance (except for features that are a direct effect of that difference).

I mean worst case people post in the wrong thread and so it’s the same as now lol. I think people can figure it out. Don’t disappoint me people.

Just in case anyone wasn’t in on the joke the gefs didn’t cave. Even out to day 16 it was pretty similar if not slightly better then the 0/6z runs. Model death match still on.

I’ll wait

@frd @CAPE @WxUSAF there is a dichotomy long range. The strat crew keeps hinting Feb could rock. The MJO/AAM/GLAM gang thinks we torch feb. There are conflicting signals. The progression of the tropical forcing and angular momentum favors a warmer canonical Nina Feb. The SSW progression favors Feb as when we see the greatest impacts on the TPV and subsequent blocking and cold intrusion into the mid latitudes. The question is which driver wins that fight or if it’s a stalemate does that end up favorable enough for us?

People who only want to hear what could go right and not what could go wrong.

Yea “long range pattern thread” and “medium range storm thread” thread.

That too...with a flow straight off the pole the STJ gets shut off and even if the cold does come east we can go dry.

I would bump the GEFS to a 8 long range and the EPS isn’t good but it’s not a 1. It does still have a -AO and there is at least hope with that. Last year with that pac and a +AO was a 1. I’d give the EPS a 2/3

It has some correlation to cold. It definitely correlates to cold in the US but that correlation becomes weaker the further east of the Miss you get. Almost every arctic outbreak does coincide with a -EPO because it produces cross polar flow. But most of our Arctic outbreaks don’t feature significant snowstorms. Details matter but in general an EPO ridge will focus the cold too far west of us and unless there are mitigating coinciding factors like a -NAO or displaced TPV in SE Canada the storm track will be to our west. The gradient often isn’t that far away so the cold can get in behind each wave but with the longwave trough axis so far west anything that amplifies will usually cut. You get a little NW of us or into New England and that can be a great pattern with storms riding the gradient. But we usually end up SE of the track here. Only in very rare cases like 2014 and 2015 does it work out and they took some rare combinations of a displaced TPV and an extremely positively tilted poleward EPO ridge. Looking at all our warning snowfalls the EPO was almost evenly split. The EPO alone just doesn’t correlate much to our snowfall. I will end with this since some have pointed this out...if we need true arctic air going forward to get snow then the EPO probably will become more correlated to snow. But that would be a VERY BAD thing!

Wrt the GEFS v EPS... hope this illustrates the difference better features 1-4 are the same on both. But 5/6 are there on the GEFS and not EPS. GEPS is kind of in between. Feature 5 there is crucial. That extension of the pac ridge into the high latitudes taps true polar cold and directs it down into the Conus. That creates a broader colder trough in the US that presses the thermal boundary into the east allowing storms to amplify further east under the block which leads to feature 6. The SE ridge (2) can be mitigated by 5/1/6 in that look. It’s a critical mass thing. Get a cold enough profile to set off the chain reaction we want and that all starts with that ridge up near AK. The strong 50/50 signature along with a cold enough airmass will stop storms from cutting end the SE ridge could even end up helping us to stop suppression. But if that ridge near AK fails and not enough cold gets into the pattern the trough won’t press, it will pull back fully into the west and storms will cut and then wash out when they hit the blocking ridge. The NAO block will be rendered useless. ATT I favor the GEFS look. The high latitudes have favored ridging this year and the pacific progression favors that. But I’m not ruling out the EPS. I’d like to see it flip back. Hopefully I’m not driving everyone nuts with this stuff. Just trying to explain what could make the pattern go one way or the other.

It’s more about potential energy. An increase in water temps from 80 to 85 will add a lot more heat/energy then an increase from 35 to 45 in the higher latitudes. Same with the air. Warning in the tropics will add a lot more heat then the warning in the Arctic does.

My source is only updated to day 13 so I can’t say what happens at the end but day 9-13 looks much better on the GEFS still with a more elongated trough that extends into the Atlantic vs dumping it all into the west right after the initial dump around the 15th. 0z EPS 12z GEFS same time

I agree with that. We shouldn’t be discussing details with a storm more then 7 days out anyways. I was thinking more for stuff day 3-6. We used to have threads before we decided that was bad luck.

@CAPE one last point wrt the pac issue. To simplify the relationship with the N PAC vortex...the warmer base state of the PAC has enhanced the jet and that in a nutshell means there is going to be this big firehose of warmth directed somewhere. And unfortunately we are downwind of it. But where would we rather it directed? Across the mid latitudes (directly at us) and enhancing a screaming zonal flow around the mid latitude northern hemisphere that also enhances the PV to its north! We have seen what that looks like plenty recently right? Big ring of red around with a blue ball of death over the pole. Good luck! Or do we want a vortex in the north Pac to take the fire hose and direct it up into the high latitudes and at least disrupt the PV and create chaos! Either way the whole base state is warm. But one seems to give us more of a fighting chance. Again this is just a 10,000 foot view observation.

@WinterWxLuvr @CAPE I added some ETA to my last post before even reading these posts because of “this” issue. I agree with you Cape that multiple threads would be better partly for this reason. There are discreet threat level thoughts, long range longwave pattern level, and then even super long term decadal level patterns thoughts. And they all get mixed in here. Sometimes I am making an observation about something pertaining to decadal level pattern and people take it as pertaining to a current threat. I can multitask in this one thread and it doesn’t bother me that much but some seem to confuse these different trains of thought and conversation and it gets frustrating.

True but that enhanced pac jet (which isn’t really a Nina issue it’s a byproduct of the increased thermal gradient in the pac due to the warning base state supercharging the jet and it’s been there regardless of enso for a long time now) has put us in a double bind. You’re right that with a strong pac jet the trough in the N PAC directs that pac firehouse up into Canada and destroys our cold source regions. But if that N PAC trough relaxes the forehose usually ends up directed right into the lower 48 and that leads to either a totally zonal puke pattern or if there is a trough out west a super ridge in the east and we are 65 degrees. That enhanced jet also makes it very unlikely to sustain the kind of crazy concurrence of variables needed to offset it. Yes if we could get a perfectly placed stable full latitude east based positively tilted EPO ridge that would mitigate the pac. But the enhanced jet makes that even more unlikely then it would be normally (and it’s pretty rare to begin with). That fast jet has destructively interfered with every attempt at high latitude ridging and PV disruption for years. Imo the fact we had a N PAC trough (imo aided by the very off warm over cold SST pattern) muted the issue and it’s not a coincidence that coincided with the first stable long lasting winter high latitude blocking regime we’ve had in forever. So the double bind is this...with that N PAC vortex you direct an enhanced pac jet into Canada and wrench the thermal profile of our source region. But if you lose that the pac jet goes zonal and blasts pac puke into the lower 48 and the fast zonal flow in the pac destructively interferes with any blocking attempts so we get a +NAO and ridge in the east! I don’t see a “win” there but the lesser of the evils imo is the N PAC vortex. Maybe Im wrong but given enough chances I feel the odds were better if eventually getting a couple of the perfect track storms to be “just” cold enough v battling with the imo more destructive effects of the pac jet in a more zonal flow. But I could be wrong. It’s frustrating. We really need that pac jet to relax but it hasn’t for a long time and that is regardless of enso. ETA: this is a bigger picture long timescale point. I think this year we might get a window where we get that rare “just right” Goldilocks in between balance. But longer term we’re going to be really frustrated if that’s what it takes to ever snow.

I think the ridge axis (too far west) out west is a bigger issue. As I argued last night the NAO may not be a picture perfect Davis strait Rex block there...but it’s not supposed to be that hard to get snow. We don’t live in the tropics. A regular old Greenland -NAO ridge has resulted in snow here plenty. Maybe not a 20” HECS but a snowstorm. You can nitpick a minor flaw in almost any pattern. But there is way more right then wrong there. Yet lately is seems unless everything is 100% perfect in every way we can’t buy a snowstorm near DC. ETA: I said near DC because DCA is a joke. It doesn’t surprise me if a runway on an island south of DC at sea level lower in elevation then everyone around them can’t get snow. But even places around DC that average 20” a year can’t seem to buy any snow lately.

Gotcha lol

What Pac tele are you referring too? We’ve had a +PNA since late Nov and the EPO has no correlation to snowfall here.

Me either. I debated not even bringing it up but I’m not a head in the sand kind of guy. That option is there. My guess is that their progressing the pattern too quickly. We also haven’t seen any impact from the SSW yet. Lastly we’ve seen blocking regimes head fake a break down on guidance many times before.

Imo it doesn’t matter once we get to March anyways. The shorter wavelengths have made March a wildcard in a Nina. There doesn’t seem to be any correlation with some Nina years ending cold/snowy and some a torch with no regard to the strength of the Nina into late winter. Nina forcing is bad so it’s not gonna hurt to see it weaken but we’re at the point where it’s becoming irrelevant because by the time the lag wears off the part of the season where Nina has much impact has ended.

That isn’t actually a good look. That’s the first wave (of what was supposed to be a more extended period) but that isn’t going to produce a snowstorm here. 1. That trough doesn’t have enough depth. 2 look at the ridging in front of it. 3. The antecedent airmass sucks. The cold is behind the wave. so...ridge in front, crap airmass, no depth...any storm with that trough is going north of us. If you look at the individual members you will see what I mean. It would be the next wave that has potential. But the problem is there is no next wave on that EPS run. It retrogrades the pattern too quickly such that nothing can amplify east and knock down the WAR and becoming a 50/50. Instead the trough axis pulls into the west and everything would cut then wash out. The next wave (the one I identified on the GEFS last night as a good threat window) never makes it into the east. It’s only one run. I’m not jumping on this. I was just pointing out that it’s there. The EPS paints a fail picture. I’m not ready to jump ship because of one bad run though.

I’m not going to analyze it or freak out but I’ll just put it out there. The 0z EPS is an unmitigated disaster. It lost the poleward EPO ridge and develops a flat central pac ridge which directs the pac firehouse jet right into the US. There isn’t even any transition because that happens so fast the pattern is wrecked before the next flux of the NAO can even do us any good. It’s just one run. GEFS at 6z still looks good. Just hope it’s wrong. It shows exactly what I said my fear was if the N PAC pattern relaxed.