psuhoffman

I’m gonna ignore all other evidence and assume numbers 4/5 know what’s up

It might encroach the southern edge of the NAO domain some...but its not the kind of look that will influence the pattern the way we need. A better sign is the guidance ejecting the AK vortex...although todays GEFS seems to take a "step back" on that. I don't care about the blue over us if there is still a AK and Greenland Vortex combo...it will not be cold enough in all likelihood regardless of a day 15 look. This is a composite of warning level snowfalls at BWI with a somewhat similar Pac look to this year. Notice where we need the ridging in the NAO region to be.

The ridging I see is mostly south of the NAO domain.

But it’s close day 10 to a flood

What is messing this up in the broader sense is the longwave pattern. The upper low is stuck under blocking in canada yes... and that forces a south track of that feature (considering where it starts out) and that is why a ridge near Hudson Bay can sometimes work for us with a crappy background state... but in this case the wall to wall lower heights all across from AK to the NAO is blasting warm air across the continent. The problem isnt really the upper low. I guess it is if you were hoping to salvage any frozen in spite of the fact the antecendent airmass is a rotting POS. Then yea...the only way was to get a damn perfect H5 track and a bombing surface low to our east. But that is so rare. The real problem is the surface low is going to try to seek out the baroclinic zone and that is way way way north. So even with a pretty ok upper track the surface low is going to cut, on some runs it even ends up NW of the upper low for a time. That is why we see those wacky outcomes. If there was any cold at all this would be a big snowstorm because the surface low would stay to the southeast of the upper low along the boundary. We are left praying for some 1/100 perfect upper low to track under us and have an amplified enough system to create its own cold air...how often does that work. More for you than DC I guess...but its the larger picture that is the real problem imo not the micro level issues with the H5 track.

This sums it up

I am SHOCKED the CFS didn't work out, it's always so reliable.

If the heat transport from those waves is not directed towards the mid/high latitudes in the northern hemisphere its irrelevant. I think it was bluewave who showed a great loop where it was obvious the majority of the energy was being muted from transporting poleward in the NH. Way more was being directed into the SH actually.

Notice I never even factor the snowcover/ice stuff into my thinking in the fall lately. Its useless. IMO it shows backwards correlation because it was useful as a predictor during the colder regimes. But with ice and snowcover reaching record low totals almost every fall now...we will naturally see a significant "increase" once the cold season sets in at high latitudes. So that is less useful as a predictor of what the pattern is actually doing. I don't need a ton of statistics to tell me that, its common sense. Tom nailed the PV. Absolutely 100%. And his equation shows predictability way above climo which is rare for long range seasonal forecasting. I have just begun to dip my feet into some of the factors he incorporates. I am not even close to where I want to be yet...but I will get there. I will do a lot more reading and research in the dead time next summer. I think there is definitely something to it. From my limited understanding of the correlation between AAM global phases and the pattern... what sticks out so far, incorporating some other resent studies and observations...is that there seems to be less coupling between the older typical indicators like enso, north pac sst, atlantic sst...and the MJO and other tropical pattern drivers. This decoupling will result in non typical results if we just look at things like the enso state because the forcing they were associated that actually impacted the pattern is no longer the same. Now I don't think this is true of a strong enso event. We have seen canonical nino results from years like 2003, 2010, and 2016. But in years with a weaker enso signal...its more likely for other factors like the AAM to not be in alignment with historical expectations. The warmer base state and changes in the IO and western PAC SST are causing other factors to be more dominant than enso when its a weak signal imo. One troubling thing... some of those changes are biasing those other factors towards what we would typically associate with a nina atmospheric response in the Pacific. If that is the case, and it seems to be some truth to that, we will lose "enso neutral or weak warm" years as a good probability for snow. In the past enso neutral or a weak nino was a decent chance for a cold/snowy winter. Not as good as a moderate nino of course...but still a way better odds for a snowy year than a nina. But lately those years are skewing warm also. Obviously we will need more time to confirm this...and reasearch...but just thinking out loud... if this is all true what our new climo would be would likely be even more extremes. The warming does seem to be increasing our chances of hitting BIG storms when the pattern is conducive...but we are spending less and less time in a conducive pattern. So the result of that could be bigger big years and worse years when its not one of those. In the end our "avg" might not change much but how we get there will become even more skewed between crazy snowy years and crap years in between.

He has become a total joke. He was always a hype machine and biased cold/snowy but his discussions and videos used to at least be an interesting and often educational experience. He would discuss different looks and options. Now all he does is release propaganda where he cherry picks one run that supports his predictions or rants about his anti climate change agenda. And he has become even more ridiculous in the lengths he will go to support his forecast. For example using a year like 1978 when we got a cold period during a warm mjo rotation to justify his ideas. He is either crazy if he really doesn't see the difference between a season with a cold base state, canonical nino, weak PV...and what we have now. Using weak warm MJO waves in very cold winters is NOT a comp to seeing a super charged warm phase MJO wave in an already warm background state. So he has either lost it...or he is flat out lying to everyone to support a forecast he knows is going to bust.

Since mid December...when our climo really starts...while we have had 3 disticntly different patterns...they all featured either an AK vortex or a ++++NAM. That combo won't work. Yes we have had different factors shifting around...but the issue is we got one of the worst combinations of a nina/nino that in concert are killing us.

Maybe...but what you are seeing on the 300 hour guidance is not really a true -NAO or NAM state flip. It's the ridge under the TPV getting caught in a sqeeze play between the shifting AK vortex and the TPV over and north of Greenland. I do not see the wave breaking necessary to really force a permanent NAM state change from that...as of yet. The feature you are seeing isnt bad...and if the AK vortex does drop into central North America that is good... but I am not as hopeful that what your seeing day 15 is the permanent NAM state flip we need. I do think there is a chance that does happen, but its likely later in Feb or March if at all. We kind of have a mix of signals...we talked about in the fall how there are so many conflicting signals...but the combinations isnt going our way. We wondered how it would play out...and we did get a mix of some nino and nina like pattern features. Problem is the ones that ended up dominant were the worse of both worlds. We got the ridge near Hawaii and +NAM associated with a nina, and we got some central Canada ridging associated with a nino, but that combination isnt really going to cut it. Often in a nina base state winter we do see a more favorable NAM state phase change towards the end. My feeling is that the shortening wavelengths aid in heat transport and wave breaks attacking and disrupting the stable PV and make it more possible to get some blocking later. Shorter wavelengths can also make it more possible to get a fluke storm without help up top. So there is some support to the idea that the current mess we are in could change but that typically doesn't happen until later in Feb or even more common in March.

Don't disagree with your points... and I would also recommend anyone who gets emotionally invested (a lot of people) in day 10 forecasts should take a break... but for me personally I can look at long range...knowing full well how low probability things are, analyze the permutations of where the pattern could be going based on the limited NWP clues and seasonal tendencies, without it driving me crazy when particular results I want do not happen. But for most who cannot do that...avoiding long range is probably a good idea.

We cannot overcome an AK vortex if the NAO is raging positive. We can and have snowed with an AK vortext...especially as we get later in winter...if the NAO is negative to block the pacific onslaught. But with both features the pac obliterates any mid level cold across north america. Likewise we can overcome a +NAO with an epo ridge. But if we continue to see an AK vortex AND a +NAO we are screwed. Yes I said SCREWED so here comes a post from you know who complaining about "how dare I declare winter over". Joking aside, maybe one or both of those features change from here on out, I would have more hope in the AK vortext than the NAO, but we are losing valuable prime climo everyday and odds of ending up with anything other than a bad winter are decreasing, not that I am surprised by that fact. But there is always "hope", there have been very rare cases where the pattern went through a complete reversal late...had the flip in 2018 happened maybe 2 weeks earlier we probably would remember that as one of the great turnaround years also. But when its so hard to get snow here to begin with...spending a huge chunk of our prime snow window in a shutout total crap pattern really makes it difficult. ETA: the only reason any of these threats the next 10 days are "close" is that Hudson Ridge. Those can sometimes overcome the larger crappy base state. It was actually the feature most at cause for our "bad pattern snowstorms". But even with that...we would need to get lucky with an absolutely perfect track amplified h5 system...and even then I am not so sure if it would work in the cities.

If you go back over the last 5 days or so...and look at all the different analogs spit out by NCEP and CMC for the day 8 and day 11 looks... there actually were a handful of analogs that "worked" for some snow around here...but they were almost all from years in the 1950s-1980s. The h5 analogs that were more recent from the 90s on were all from big rainstorms. Just an observation... On top of that, as bluewave has pointed out...its becoming increasingly harder to get a legitimate "cold base state" to winter in the mid atlantic. Basically if we have an uber -EPO or -NAO the majority of winter we can get a cold winter...the rest of the time we are above normal. It's very hard to get a prolonged simply "normal" temperature regime unless its a temporary period of transition. Pretty much we need a very anomalous ridge in either the EPO or NAO domain to dominate...or else we are well above normal for winter.

DC could get 2" of snow the whole rest of winter and that would make your prediction true.

This is what I am chasing at this point...

Depends what our expectations are... if we are looking for some epic save where we manage to end up above climo for the entire winter just from snow Feb 15 onward...then yea that is incredibly unlikely. Only happened a few times in 100 years and only twice in the last 30. 1993 and 2015. But if we are simply looking for SOME snow and to creep out of the "total dreg dumpster fire" category winter like 2002/2008/2012 and into the just "typical" not good year like most years other than the rare 96,03,10,14 type years... that is more realistic. Still not "likely" but not as super lottery type odds. Getting a late "save" that brings us out of total "dumpster fire" into "just regular bad" year is more common. Something like 2018, 2009, 2007, 1999, 1976, 1972. Those are all years where BWI went into February with very little or no snow and then ended up at least closer to "median" by the end from either one lucky storm or a period of some snowfalls. That is a lot more common and a more realistic.

They did...I didn’t include every example. I would say 2015 and 2016 were the rare cases where DC beat avg without an otherwise epic winter. Although the pattern in 2016 was pretty awesome just didn’t live up to potential imo. 2015 was a true lucky result.

DCA chances of above mean snowfall is only about 30% any year. So it’s not shocking that tossing 2/3 of winter doesn’t help the odds. It’s very rare for DC to beat avg without it being one of the rare anomaly winters like 1996/2003/2010/2014. Typically DCA either finishes way above avg or below. What DC should be hunting for is to get to hear a median winter which is about 10” and happens much more often with a bad start in non great wintes. That’s a more realistic goal imo.

Also wrt the mjo...it wouldn’t matter much if it managed to sneak into 8 at low amp as the wave dies for 1-2 days. The fact that it went to 3 stdv in phase 4/5 then dies as it reaches cold phases is the important thing. A strong wave in the MC will have done the dirty work ushering in an awful pattern. It will take an equally strong influence to counteract that. If the mjo continues to go strong through warm and weak through cold phases that’s a loss. Plus there is some feedback circular nature to it. When the mjo is working in symmetry with the other influences that cause the typical phase 8 central pac wave (central/west based nino) we see the canonical pattern. But when the mjo is out of sync with the background state the response is often muted some even when it’s in cold phases. We see the same in reverse in good years. A weak wave into warm phases isn’t usually a death sentence to winter after a strong cold phase wave. If we are in a cold base state a weak mjo wave won’t always derail that. The good news is with the mjo looking to be a weak influence ahead if we do get a change in other factors it won’t be counteracting that. But the mjo alone isn’t going to save us. We need either the central pac pattern or the high latitude one to flip and it’s apparent those are being driven by more than just the MJO.

His video was good but I think he made more of the VM than it is. We’ve had very cold -EPO winters in a VM pattern. 2014 was one. I even think the example map he used to compare a VM to a PDO that was 2014 on the left. Lol The mjo spiking so high into warm phases in the core of winter was a bigger deal. But again that’s an effect not a pure cause. But we can see the same effect we get in most warm winters where the mjo goes ape into warm phases and can barely sniff cold ones. That warm pool in the north pac has little to do with that. The energy released from the tropics is several magnitudes greater than water in the north pac. The configuration of the mid latitudes was all wrong to transport heat into the high latitudes and disrupt the PV this year.

The eps weeklies eject the vortex out of AK into central N America. Also weakens the NAM back closer to a workable look. Sets up a gradient pattern but with us on the right side for early to mid February. Best look is probably this week If that’s right that would imply we’re in line for waves and on the right side of the boundary. I know it’s worthless but I suppose it’s slightly better it looks good simply because when it’s an epic disaster that’s when it’s always right.

Lol...they’re actually good I’m just not sure anyone gives a crap.

Btw wrt the mjo...I don’t think it’s going to save us but I also don’t think it’s going to kill us in Feb. After a brief nudge into 6 (and even that signal is conflicted if you look at the actual convection, it likely goes null. Other factors are likely to drive the bus in Feb imo. Doesn’t mean they will be any better but I suppose they can’t be any worse so there’s that.