psuhoffman

Kids keep asking about snow. Might take them to black water falls for a day.

Some of the Gefs members really amplify the mjo wave over the MC. It’s sort of a 50/50 split. But either way we will be getting some destructive tropical forcing mid Dec. How much and how long likely determine where we go long term.

Long range and especially seasonal is getting increasingly difficult because we are seeing some influencers configured in ways we’ve never seen before. The pacific sst is completely out of wack and the QBO has been behaving odd the last several years. Add in warning across the board and historical analogs are less useful. I am guarded but getting somewhat optimistic this ninoesque pattern is real. It’s pretty consistent across all guidance and getting closer everyday. It’s being driven by IO convection and the retrograde of the AK vortex, both of which is well underway. But I think 2 factors determine if we end up with a December that produces and doesn’t just tease. We’ve had some decent patterns in Dec recently that did us no good. The first 10 days I think might be a challenge due to the lack of any true cold air source. The recent pattern has prevented any cold from building on our side of the pole. It will take a while to fix that and initially the ridge in Canada is a bit too far southeast to allow cold into the equation. That may change as the pna ridge retrogrades in response to the AK vortex retrogression. In the meantime we’re dealing with a crap airmass. It could work with a perfect track and timing but it could be frustrating if things don’t come together perfectly. The last factor is what happens after Dec 10. I think the MJO will give a big clue as we get closer. There are signs it may finally try to propagate through the Maritime Continent mid December. Those are the warm phases for us. However...I’ve found that when you get a weak or fast wave through phases in conflict with the base state it doesn’t have as much impact. That’s why some weak MJO waves in cold phases didn’t save us the last few years and it’s why some warm phases didn’t kill us in colder years. As we get closer if we see signs the mjo is racing through the MC at a weak amplitude that is a very good sign this pattern may persist. If we start to see signs it wants to stall and amplify while near the MC that would hint this was just a very temporary blip and the base state to the winter pattern is likely to be hostile. It’s too soon to say right now. We will start to get hints soon. Happy Thanksgiving

1996 lol There were also a couple Nina's early in the 1900s that judging by the statistics definitely did not behave like what we consider a "typical" nina today. NOT saying that is what is happening here....yet. Many have pointed out the enso north pacific sst combo is very unusual so maybe a canonical nina isn't in the works. Way too early to draw any conclusions though.

It's possible I missed some of that...once the big ugly pattern set it I kinda knew it was over and so I checked out pretty much. I would glance once in a while to see if there was any hope but there were days and days that would go bye without me taking more than a quick glance. But what I did see was more bad than good even out at range.

This look With that SW-NE ridge axis across Canada centered just north of Hudson Bay is actually a really good one that has lead to many moderate snow events in our region historically. I’m not getting into the “but will it happen debate”. But I am of the mine it’s better to look good than bad. Last year proved having the long range look awful all winter isn’t a good thing. Additionally seeing the pattern look nothing like a typical Nina (and that feature is not way out in fantasy land) is a positive development. The pattern analogs are littered with nino years right now. And even Nov 1995 in there. Sometimes we get lucky and the atmosphere just does something crazy. Not saying I feel optimistic yet...but there are positive signs.

Get the center of that ridge in western Canada a bit further NW and it’s a $ pattern.

Sorry I know you knew all that. My post was meant to add for some others who might be reading. I should be more clear about that when I post though.

depends how we get that numerical average. A neutral NAO with a crap pac doesn't really do us any good. But if the average is derived from a mix of positive and negative periods...that would be just fine as the negative periods would present windows of opportunity for us. Furthermore...there are times when the NAO can be negative but from an anomaly in a position that does us very little good...(extremely east based -NAO) and there are times we can get a bootleg block near the western edge of the NAO domain and the NAO numerical value is actually neutral yet the pattern is great for us. The devil is in the details.

Winter forecast. I used analogs and pattern recognition. Factors include ENSO, QBO, PDO, AMO, AAM, Atl SST, soil moisture, and trends. December I expect the predominant pattern to take on a configuration that resembles... January as the PV reaches its Max and the jet stream settles into its dominant winter configuration I could see things evolve to Finally in February as the same old regulars (we all know who) tell us everyday how awful it is as if we don’t know I think the pattern might transition to For anyone who makes it to March expect

I dunno about the luck but we do dumb pretty good

Where’s the blue???

And which of those is favorable right now?

First winter call

I’m not sure how much the former factor will help. There is often a lag effect between enso and pattern and even a weak to moderate Nina isn’t exactly great snow climo in our area. But I am very much in agreement on the latter. The pacific SST is really in contradiction between the enso regions and PDO regions. There aren’t very many good analogs to this configuration at all. I’m still being pessimistic but that’s probably just me not wanting to set myself up for a disappointment. I could see a scenario where this year does not behave like a typical Nina.

I think you should say this in a slightly different way a few times everyday.

I was thinking 65 which was a weak Nina. Why do you cite 67? That was an enso neutral winter during an extremely -NAO regime. Add in warming since and I doubt it’s a good comp to now. Hope I’m wrong.

Thanks for the info...love your work. But keep in mind all 4 of those years you cite were pretty sucky for snow here. 67 was ok but not really compared to the period it was in. The other 3 were all below normal and frustrating as we missed almost every storm just to our northeast. Nina’s are a lot less hostile in NYC than our area.

I see the similarities. And while 2000 was one of the best snowfall Nina’s in our area I also think expecting a repeat of that 2 week stretch in January is risky. We torched with no chance at snow the entire rest of that winter. What if that short period of blocking didn’t happen. Or what if we simply didn’t get lucky and nothing came of it. I tend to think of the outcome that season as more lucky than good. A repeat could end up a disaster. Please convince me otherwise though. I could use some optimism.

@Winter Wizard what sticks out for our area is when you look at each snowfall event you find that even the ones in a +AO/NAO Nina came during a period of blocking within the +AO. 2000 was a good example. All the snow came during a 10 day period with blocking. The rest of the winter was virtually snowless.

I posted a chart of the state of the major indices before all of the Baltimore/Washington areas warning snowfalls going back to 1948. Its in the snow climo study thread. As @CAPE said we need some HL help. An east based poleward EPO ridge can compensate for a bad NAO. The AO is tricky because there is overlap from both the EPO and NAO so you get some cross contamination when you simply use that index. But taken holistically it’s evident we need some help up top somewhere. We’re simply too far south if you get a contracted polar jet and zonal pattern. We need buckling somewhere. Specific to a La Niña the NAO becomes even more important. Baltimore rarely gets any snow of significance in a Nina without NAO help. I’ve not run the numbers but it’s likely similar for most of the region. It’s makes sense..in a Nina the pacific ridge is likely to be too far west to get er done all by itself. Add in a lack of STJ and fast NS jet and it makes sense that without the NAO buckling the flow in our favor we would be SOL.

It could make sense if there was a particular detail that caused the divergence in those years...and you know how and intend to tease out and compensate for that factor...to come up with a workable forecast. But putting together a pattern composite of those years as a forecast would be bad forecasting imo.

I don't agree with what he did. But I also don't agree with some of the analog composites being throw around (not by you) that throw together an amalgemom of vastly different Nina years to give an average that is skewed or some mix of opposite patterns that is equally unlikely to occur. With the exception of 1996 which was an extreme version of type 2, there seems to be 2 very clear distinct class of nina winters. When there is a flat central pac ridge we tend to get much more southeast ridge and +AO and those years are some of the worst complete crap non winters in the mid atlantic. In nina years with a more poleward pacific ridge we tend to get more trough into the northeast and also a higher probability of some blocking and while those years are still usually dry due to a suppressed STJ we at least get some respectable cold and closer to median snowfall. The problem I see with some of the analog sets being throw around is they use way too many factors and end up taking a small sample that includes years from both of those types and the average H5 pattern you get is simply an average of two opposite patterns and unlikely to be what the dominant winter pattern really looks like. One example I saw thrown around last month was particularly egregious. They were filtering for QBO and ENSO matches. Problem is there were only 3 years in that dataset. And one was 1996. 1996 was skewing the mean of the whole set to look like a -NAO was likely when both of the other two years had a positive NAO. That analog composite was completely misleading and useless. I think some people that don't really understand how correlations and analogs work are starting to have too much fun with maps.

The MC phases are more correlated to a +AO than the IO and Dateline phases. This is speculation but I think the relationship is an effect of the central pac ridge promoted by those phases tightening the pac jet and the gradient between the Hadley cell and the PV thus speeding up the flow around it and by effect promoting a stronger more pole centered symmetrical PV.

Almost every one of those factors is opposite what we want. That’s “average”? I guess lately...