psuhoffman

He is on a growing list of people I completely ignore. I don’t have time for assclowns in my life.

Don’t drive angry

What would you do if you were stuck in one place and every day was exactly the same, and nothing that you did mattered? That about sums it up for “Cohen”.

Seeing that Aleutian low pop up on guidance is making me feel better. Going back to those QBO analogs, that was a feature of many of the “good” ones in that set.

What if there is no tomorrow? There wasn’t one today!

I'll give you a winter prediction: It's gonna be cold, it's gonna be dark and it's gonna last you for the rest of your life.

La Nina’s climo does show a snow anomaly minimum over our area. But it’s not nearly as localized as the snow hole that year was.

Depends. A slightly pos AO doesn’t mean much for the rest of winter. A very +AO in November and December tends to favor a +AO the rest of winter. Overall a +AO is just a bad thing in any winter month. We only have 3 of them and when a strongly + AO sets in Dec to Feb we often can kiss a long stretch of our limited window for snow goodbye. But overall I am more on the chaos side of things. There are some very rare winters like 96 2003 and 2010 where so much was right that we were destined for greatness. And there are some really awful years like 2008 and 2012 where so much was wrong that even a decent year was unlikely. But like 80% of our winters I think luck can push us one way or the other between a typical crappy 5-10” year and a good 20” year in the DC/Balt region. All you’re talking is 1-2 storms between those opposite fates. We remember 2 years ago as bad but all around us had above normal snow. We just missed 4/5 of the good storms to effect the general region that year. And in different ways. Bad luck. 2014 and 2015 seemed like we got lucky every opportunity. The pattern wasn’t even that good most of the time. I suspect this winter will be in the variable pattern where luck on a few threats will determine our fate type.

Fringed

No two seasons are 100% alike. Even the most similar of seasons wrt telleconnections aren't complete clones. There are always subtle differences here and there. And then there are the multitude of smaller variables that we really cannot accurately measure and factor into the equation on a seasonal scale either because they are too delicate or because we have no ability to predict them at long leads. That is why in every analog set there is some variance to the results and sometimes an extreme outlier. It's easier in hindsight to "throw them out" or analyze why that year was an outlier, but going into that season no one expected that result. Look at 1995 and 1996. Back to back years, with totally opposite results, and each is in the opposite analog data set from the results you would expect. I wasn't even saying you are "wrong" per say, just that it seems from my observations of your posts that you have a tendency to latch onto things in an attempt to prescribe a level of predictability that simply doesn't exist in long range and seasonal forecasting. Even some of the best seasonal forecasters only hit about 60% of the time. The problem isn't so much what your expectations are, its that you have expectations at all when it comes to long range snowfall.

Does it ever occur to you that chaos, or a large number of tiny variables that we cannot accurately predict, will have a greater impact on our snowfall that you seem to take into account when you make these very specific “expectations”.

You're right, I think I was confusing 94/95 and 14/15 wrt how they evolved. 14/15 was somewhat similar to 06/07 in that they started more "classic" nino looking and evolved opposite of most modoki into a central pac based event. Of course 07 and 15 had such vastly opposite results wrt snowfall that doesn't really help much wrt classification and gleaning meaningful expectations from that. Of course the SST is the northern PAC region was much more favorable heading into 14/15 than 06/07 and that could have a lot to do with the different results.

Agree with those 2 points completely. It just gets more complicated wrt parsing exact types of modoki. Last year there was a pretty heated twitter war over classification between people using the older definition of modoki and some who were using the newer more restrictive one. It wasnt very productive in terms of advancing anything useful for a forecast.

Love your work. I would love your thoughts on this regarding modoki nino. When there was a pretty heated debate online about nino classification last year I looked into it a bit and found some pretty convoluted results. It seems initially, according to papers published in the 2000's "modoki" was used to describe any nino that "originated" in the central pacific and propagated eastward, as opposed to the classical nino which originates off South America and propagates west. More recently there now seems to be different definitions, one that requires the water to remain colder to the east of the central pacific. This is creating a lot of confusion imo around the discussion wrt nino types. 2002/3 and 2009/10 for instance, are generally considered modoki but both evolved into a more classic basin wide looking nino for a large part of those winters. 2006/7 is even harder to classify as it started in the fall as a classic east based nino and then evolved opposite of normal into a modoki looking nino by late January/February. It is harder to evaluate some of the older nino's with limited data but from the last 30 years, it seems only 94/95, 04/05, and 14/15 were purely modoki and stayed modoki through the winter period by the second newer classification of modoki nino. 02/03 and 09/10 started as central based and then propagated eastward in December before fading back into a modoki look again in spring. 2006/7 evolved completely opposite of a "typical" modoki. Then there is the issue of how those differences impact the pattern. It's hard to draw firm conclusions with such a small sample size. But at least here in the mid atlantic, our two best results 2003 and 2010 were years where the modoki evolved into a more east based look for a time. 2005 and 2015 did have some similarities in that they were both the most consistently modoki in nature and both had a somewhat similar pattern in where they focused the core of the cold and snow over new England. But then what do we do with 1995? Perhaps throw it out as an outlier? And what of 2006/7? And of course luck and other influences have an impact too. 2006/7 started awful but then had a pretty good run of cold in Feb and Mar with several opportunities but most failed for the urban corridor. 2004/5 could have easily ended better for the mid Atlantic with several good threats that failed to maximize potential. I am left unsure exactly how to parse the data. If we start breaking the enso into such detailed events we end up with such small sample sizes its hard to get meaningful results. If we look at the whole group we get such varied output its also hard to get meaningful results. What is obvious is that having a nino in general increases the odds of above normal snowfall, at least here in the mid atlantic, and that having a moderate nino is the best to really stack the deck in favor of snowfall. But beyond that, it seems to get really ambiguous or inconclusive, at least from my initial look at the data.

It depends how suppressed the pattern ends up. That h5 look in Jan or Feb I bet it’s not a bad bet to get a wave under us. Quite a few gradient systems worked in 2014 and 2015. The suppression then was due to a favorable PV location but an NAO block with 50/50 can mirror that same effect and offset a west based epo ridge. But last winter when we saw that same look I remember finding quite a few good results historically from that type pattern. The problem was the NAO part never materialized and so the pacific ridge dominated the pattern. But even with that fact we still got a couple waves to stay under us in February! It wasn’t a total shutout. Just not the epic pattern we wanted. Add in a true NAO block and its a pretty good pattern. Keep in mind many of our snows don’t come with a “perfect” pac/atl combo. That often just least to a huge trough and dry. Often it’s some convoluted combo that works. More recently it’s been a good pacific finding a way so I can see being biased toward that, but historically a good Atlantic offsetting a mediocre pacific is even more likely to produce snow. But I agree 100% with that fact that relying on the NAO is risky and I would prefer a good pacific look that doesn’t require the Atlantic to offset it at all. So yea this isn’t ideal. But it’s too early for me to go overly negative. One thing my research has shown is that every winter is an island. There is almost no pattern or predictability from one season to the next. I won’t let last years frustrations cloud this years potential...YET lol.

I don’t get all the lamenting the pattern coming up. I only see the SE ridge truly flex for 48-72 hours as the cold initially dumps west. But after that I see a broad trough with a suppressed SE ridge and a pattern we would likely be on the right side of the gradient in Winter with. I like the look. Now that is totally dependent on the NAO blocking being legit but right now it looks it.

I wouldn’t use the results of a northeast pac ridge west based -NAO block pattern in late October to be indicative of what the results would be in January. With broader wavelengths and much more cold available I would suspect things would play out different. We did fight that ridge last winter, but we also never got the NAO help we needed to offset it. I don’t like seeing the ridge there but it’s been so long since we had a stable -NAO blocking pattern in mid winter that I think it’s easy to forget how that can mask other issues also.

The epo ridge there isn’t ideal...but I would worry more about the NAO verifying. If it does we would get opportunities in winter in that look. Last year the NAO kept verifying weaker and transient. That won’t cut it with the epo ridge centered off the west coast. But even given that, we still managed several overinning type snows during that stretch just never the epic pattern we were teased with. With a legit NAO block that pattern can work. There would be some SE ridge at times but there would also be storms forced to slide under at times. I wouldn’t take the results in late October with significantly shorter wavelengths and cold to be indicative of what would happen in winter. Now all that said, the NAO has been like chasing a white whale lately so I would prefer a better pacific look where we didn’t need the NAO. But I am interested to see if the blocking comes to fruition this time and if it does during winter I wouldn’t be as concerned about the pacific ridge.

Take 2004/5 and remove the god awful start and replace it with anything remotely mediocre and that becomes a pretty good year. Just a thought.

If the pattern is MJO driven, then yes. But the MJO wave configuration can shift from season to season also. Other patterns don't necessarily shift seasonally the same way as consistently either. My main point was that snowfall is so fluky and rare in the mid atlantic in October and early November that using that alone to be predictive of a bad winter is problematic. Having a cold "favorable" looking pattern early in the season might be a better way to look at it, and those results are more mixed. Like I pointed out before 1995 and 2002 both started off early with a cold look that then lasted right through much of the winter. Other years started off mild and that lasted right through the winter. Then there are plenty of years that were variable and the pattern in October into November was absolutely no indication of what would come. What I would definitely agree with is that having early snow is in no way predictive of a good winter coming. But I would stop short of saying it is predictive of a bad winter either.

Correlation and causation aren’t the same. There are so few examples of super early season snowfall outside the mountains that it’s hard to place any statistical significance on it. Yes “most” years where there was snow very early ended up not good. But when roughly 60% of all winters end up “not good” AND there are only a handful of examples in that data set...its impossible to say there is causation. Imo it’s just random chance more than anything. Look at 1995/96, we had snow in November. What if that cold shot has been just a week earlier? Somehow there is a magic date that changes everything in seasonal progression? In 2002/3 it snowed in October just to our NW. So if that storm had tracked 100 miles further south it means that winter would have sucked? I don’t buy it. It’s just a fluke combined with the fact most winters suck so anything can look predictive of a bad winter.

One of my favorite events ever was the 8” of snow up here in October 2011. No lull. Just steady heavy wet snow that stick to everything. Wouldn’t mind an early season repeat. Of course the winter that followed sucked.

This might help, this is BWI snowfall broken down by enso state years. You can see that neutral actually has a slightly higher mean/median snowfall than weak nino. The adjusted average is with any obvious outliers taken out. This chart helps give you a quick snapshot of how we perform by enso category. But I would take some of the older years in this set with a grain of salt now. Of course the problem is if we start to only look at the last 30 years we end up with too small a sample size for each enso state to have a significant data set. Catch 22

Not exactly. First of all last winter was a normal winter, and actually better than 50% of them in the urban corridor. It would have been perfectly acceptable to MOST (sorry CAPE) had it not been for our inflated expectations due to the favorable enso look. On top of that we have had plenty of great winters in neutral enso years, and even a few rare ones in nina years. So I am most definitely NOT saying we will only score a snowy winter in stronger nino years. As for a weak nino specifically... that also depends on other factors. I am just saying that a warmer base state of the PAC SST in general may mute the impact of a weak nino. And all analogs from more than 30 years ago should be taken with a grain of salt as we are in a vastly different climate regime now. But if a weak nino acts more like a nuetral that still doesnt mean we can't get snow, just means weak nino's will be more dependent on other factors. Last year the MJO and QBO didn't really help us out any. Both stayed in phases not helpful to blocking or an eastern trough much of the winter. And yet we still managed a decent winter regardless, just a letdown compared to our lofty expectations. This year with a neutralish enso we are again at the mercy of other factors and right now those other factors are in conflicting states. Some favorable, some not. To me that probably means a variable winter with some chances but not wall to wall awful and not wall to wall good either. If we simply use climo that probably means about 9-18" in the urban corridor with a bit more NW and a bit less SE. That is simply going with a straight climo expectation of what a "typical" winter is for our area. DCA median snowfall is about 10", BWI about 15 and IAD about 16. If the positive factors like the QBO end up dominant perhaps we end up with a better result than that, but its hard to predict above normal snowfall here when we typically only get 3/10 above normal winters and the signals are mixed going in. But we have had plenty of snowy winters that weren't expected to be such at this point.

Sorry it took me so long to post on this... been really busy lately and just started looking at winter a little. I agree that further refinement of these years would be needed...but I think the point of this does show that our current QBO is a positive factor. Other variables could shift...so could the QBO if it fails to continue to decline as expected, but overall if we look at all the years with a similar QBO progression they ranged from "run of the mill" normal winters to blockbusters. None were total dud years imo. CAPE, your concern looking at the H5 is valid but if we look at the actual results its not as bad. Sometimes a long duration mean like that can hide details. The worst was probably 2007 but that year included wasting the first half with a god awful pac pattern, and then getting pretty unlucky with several good opportunities the second half. 2005 could have easily been a much better result too with some luck. So in the last the QBO would argue that this shouldn't be one of the really truly dreadful years. It is always nice to eliminate those from the range of possibilities. However, with such small sample sizes there is always the chance that such a result is well within the goalposts and we just haven't had one yet. Count me in the group that thinks using older analogs is becoming increasingly problematic due to changes in the base state of the climate and SST's. The pac is a raging inferno now compared to 50 years ago. I think that is likely making the typical enso atmospheric response less reliable in years without a very strong signal. So perhaps looking at the whole scope of QBO analogs isnt a bad idea. Of course...the more recent analogs are the less inspiring of the cohort so that isnt as encouraging. The other signals right now are very conflicting. I have never had less of an opinion going into a winter as I do right now. Maybe that is my own over reaction to last year, but I wouldn't be shocked by either a total dud non winter or a blockbuster or anything in between. I can see valid arguments to support any of those outcomes depending on what factor you think is most important and will dominate. Statistics and probabilities would argue the lower end of the range of possibilities is favored simple using climo of course.