psuhoffman

It makes a huge difference in marginal events. What general area are you? I’m just northwest of town on top of Dug Hill Ridge.

I definitely am worried about the pac base state. And you may be right about a muted in between result. But I guess I went all or nothing. What my data indicated is either the Nino is able to initiate the longwave pattern we need and it’s a blockbuster year or it fails to and it’s a lame below avg year. But the better analogs skewed in favor of a blockbuster. There are exceptions like 2019 but it really did fail to initiate a favorable pattern and DC just got incredibly lucky that one fairly odd weak storm in a mediocre pattern maxed out for them. If we replay that winter 10 times I bet it ends up below avg snow 7/10 times. I did adjust the averages down about 10% to account for warming. The reason I didn’t go further was if you stratify the seasonal data by enso state, nino is the one category where we’ve seen no statistical regression in our snowfall. So far a true Nino pattern has been the one thing impervious to warming’s negative impact on snowfall. I suspect so far the increase in available moisture and baroclinic instability are offsetting the warming given a perfect storm track and the Nino longwave pattern muting the Pacs ability to flood in a puke airmass. That’s probably living on borrowed time but Im gambling we haven’t reached the cliff yet.

Except you would be excluding the best analog from a set of 4. Also if you remove 2010 and 2005 the avg at DCA is 35” so it fails to really alter the equation. Lastly…is 2010 really the outlier or is 2005? 1987,2003,2010 all have more in common than 2005. And imo 2005 underperformed. Almost every threat that winter failed to meet its potential. This is all preference. Nothing wrong with your method just defending why I didn’t go that route.

Bottom line…it’s one thing if it’s a little too warm and the 95 corridor isn’t getting snow early, but it’s not a good sign if the whole region is torching with no snow anywhere in the area until late into the cold season. That’s the only point I was trying to make.

I shouldnt have used my location. I’ll never hear the end of it now, deservedly so! But that wasn’t my point, as you know.

Nina v Nino. The euro was atrocious last winter wrt synoptic details in our domain. But that might not apply to this winter with a different pattern.

Whose complaining? I just posted snowfall probability statistics based on when the first inch falls here.

My data goes back to 2006. I found two reliable coop sites that go back to the 1950s.

If I went back further 1958 and 1966 would be in my analogs.

Yea the basic lack of climo factored into those maps is comical...but on the science side I am also not sure about the consensus of hedging towards slightly above normal snowfall. When I compiled all the analogs...actually there were some duds, like one season near to slightly above normal depending on location, and the rest were way way way above normal snow years. The analogs suggest the most likely outcome this year is actually a blockbuster 40" type winter or a dud. By dud I don't mean no snow at all like last year but a dud by Nino standards, meaning well below normal snowfall. 1992, 1995, 2007 types.

Everyone assumes I am pessimistic and usually go low. But the truth is I simply post a lot of snowfall data, and because our snowfall data has been so awful lately it makes me look like I hate on snow...but its just the numbers. And...I've been wrong 4 times in the last 13 years with my seasonal guess, and 3/4 if was because I predicted too much snow.

I took the average of my analogs and adjusted down slightly to account for warming. The numbers are what they are.

It's snowed twice up here so far...but ground temps were well above freezing both times. The first the most we ever got was a slight whitening of the ground during one heavy burst. The second no accumulation at all.

Finally posted my winter forecast

I will keep this relatively brief. This year was a struggle because there are some unique circumstances that make it difficult to find good analogs/comps. I will simply lay out my thinking and what I went with for my prediction. Key Factors I included in my forecast Analogs I heavily weighted more recent analogs and excluded anything prior to 1980. I am just not sure how much value those seasons are anymore and I felt there is enough data to hint at the pattern without having to go back that far. This was my subjective decision and does come with risks of narrowing the data available. ENSO IMO if you use the ONI data it gives a misleading perception of enso. Due to a lack of gradient between both the central/eastern tropical basin and the western PAC and northern PAC the influence is somewhat muted compared to what would be indicated by the ONI. Furthermore, possibly due to the warmer waters in the western PAC than typical, especially for an east based nino, the forcing is currently behaving much closer to a modoki nino than the SST anomalies would suggest. This makes it very difficult to pick good analogs. I decided to ignore the raw numbers and go with how this enso is actually behaving in terms of forcing. I admit this is dangerous and adds some additional level of subjectivity to what is perhaps the most important factor. But being so important I think I need to take what is my best chance at actually getting this factor correct. Based on the current MEI combined with the ONI, and the current and projected forcing, I think the best ENSO analogs are 2010,2003, 2007, 2005, 1995, 1987. Let me point out how my method could be dangerous... if we use the raw SST data 1992 becomes one of the best matches, especially factoring in several other conditions like QBO and Solar. It might be THE BEST analog...and that would radically change the forecast. However, the MEI in 1992 peaked at 1.7 during the winter season and the forcing was behaving much more like a strong east based nino, nothing close to what we see now in terms of the atmospheric response to this enso. SO I am admitting the danger here in excluding it, ESPECIALLY given the other factor/elephant in the room here... the speculation over the impacts of Hunga Tonga. QBO We are currently in a descending easterly phase. This correlates somewhat with an increased probability of blocking during the winter months. If we filter the ENSO analogs through the QBO lens the following matches emerge... 2010, 1987, 2003, 2005 Honorable mentions.... 2015 just missed based on the enso being too weak but is a close QBO match 1992 just missed based on enso being too strong but is a very close QBO match Solar We are ascending towards a solar maximum. Years similar to the current phase of the solar cycle are 2014, 2000, 1988, 1979, 1968, 1958 Trying to filter enso through the solar cycle we struggle to find any good matches unless we include historical data I struggle to weight highly at this point. We would get a good enso/solar match with 1958. Take that for what its worth. 1987 would be the closest match among data I weighted in my forecast. But honestly, I don't think the data indicates that solar alone is likely to sway the outcome that radically. Our worst probabilities of a significant snowfall season seems to come as the cycle is descending towards minimum and we are not in that condition now so while we lack many good analogs I feel solar will not be a detriment to our snowfall probabilities. Honorable mention: 1979 is a good solar match AND its actually not a horrible ENSO match if we use the MEI and forcing v pure SST numbers. Intangibles Here is where things get dicey. Almost all the data above points towards a snowy winter. But there are 3 elephants in the room that significantly increase my discomfort and uncertainty with this forecast. In order of what I think is most likely to disrupt the forecast... 1) Current Pacific Cycle 2) The warmer climate overall 3) Hunga Tonga All 3 of these are on the negative side of the ledger. WRT Hunga Tonga, I am just not an expert enough in this, nor are there enough examples, for me to be comfortable calculating how much this will influence the winter. Yes the best example is 1992 and we know what happened. But 1992 behaved like a strong east based nino. So how much of that to attribute to which factor? How similar was this eruption anyways? I've seen strong opinions either way and I am not going to blow smoke and pretend I have any freaking idea on this one. I do not feel like going on about climate change here. It's warmer. We don't have to debate why or if its permanent. For the sake of this forecast the fact that it is warmer now than it was before is all that matters and factoring how that influences this winter. Does it lead to a couple super blizzards due to increased moisture transport from the STJ? Or does the storm path shift north and we get rain? Again, there isn't enough of a sample size yet, to say. We have not had a significant nino since the last major temperature spike in 2016 to test this. Lastly... its a net positive I think that this enso is not behaving like a particularly strong one. However, the risk becomes that it is not strong enough to alter the hostile pacific base state. The Forecast After weighing all the factors I came up with the following "best" analogs, admitting that none were particularly good this year imo, especially considering the amount of subjective weighting I had to use to get them due to anomalous factors in play. 2010, 1987, 2003, 2005 Honorable Mentions: 1992, 2015, 2007 I see a lot of hedging for this winter...but my results did not show that it is likely we get a near average or slightly above snowfall winter...they showed that it is likely to be either MUCH above average snowfall...or a dud, with only one season in the full range of analogs showing a near normal snowfall winter. So, despite my reservations, and with great trepidation, I am going with much above normal snowfall for the season. Temperatures, if anyone cares, near normal. 2023-24 Snowfall Prediction DCA: 32" BWI: 42" IAD: 43" Manchester MD: 56"

Late November in 2002, early November in 1996, and the first week of December in 2009

If we want to be Nino specific, These are the DCA snowfall averages in Nino winters based on when I get my first 1" of snow here 1" by Dec 1 22" No snow by Dec 1 19" no snow by Dec 10 15" no snow by Dec 20 12"

I am NOT predicting anything based on this...but since some want to know what the "book" says... I found some of my old records...using my data back to 2006 then a local coop here back to 1958... These are just the numbers.... If I get 1" by Dec 1 DCA Avg 21" Prob of 30" 24% Prob of 20" 48% Prob of 10" 81% If I don't get 1" by Dec 1 DCA Avg 14" Prob of 30" 11% Prob of 20" 20% Prob of 10" 58% No snow by Dec 10 DCA Avg 12" Prob of 30" 6% Prob of 20" 18% Prob of 10" 53% No snow by Dec 20 DCA Avg 9" Prob of 30" 0 Prob of 20" 9% Prob of 10" 47% And it gets REALLY ugly if I make it to January without snow up here...like REALLY REALLY REALLY ugly... Again...I am not predicting anything...this is just what the statistics say, take it however you want.

I didn’t predict that it’s not going to snow in the next few weeks… I was seeing some comments to the effect of “it doesn’t matter” and I was pointing out that actually statistically it does. That’s all.

the book hasn’t been wrong yet…

I've seen comments to the effect of "toss December". It's common to torch early in a super nino. But those tend to not be so good overall also...unless we get super lucky with one huge storm like 83 and 2016. I do not consider this to be even close to a super nino, even if the ONI might be closer...there are various other factors that made this much more of a central based moderate nino imo. Those are actually more hit or miss wrt December. Yea 2015 was pretty mild but it did snow several times just NW of the cities by Dec 10th that year before it got really mild from Dec 15-Jan 15. But then there was Dec 2003 and 2009. Going further back Nino's show a more hit or miss December with the Decembers that produced snow having the better outcomes in general!

Context... I'm not saying its bad that it hasn't snowed yet. But some were basically saying its fine if we torch through December because its going to be a backloaded winter. I wanted to point out that isn't really what the historical data says is a viable path to a good winter.

I think this is increasingly true. If you go back far enough there are examples of the high latitudes offsetting a completely crap pacific longwave pattern and leading to a snowy winter...happened a few times in the 1960's but that has become increasingly rare lately. As the pacific warms, whether that is just a temporary or permanent thing we don't need to have that debate, it becomes harder for the downstream flow to mute the eastern ridge associated with a bad pacific longwave configuration.

This would be more than acceptable...

I want to head up to Stratton this weekend to break in my new boots and skis. But wondering if the "planned opening" this Saturday will end up happening looking at the weather...