psuhoffman

Just to illustrate my point. Even if we do get some NAO help were still not likely to get a great winter. But history suggest something close to median and maybe avg if we’re lucky. Not too bad. But let’s say we get another wall to wall +NAO. The best analog matches are then 1949/50, 1975/76, 1988/89 and 2007/08. I am not going to run the numbers for every location but 2 of those 4 years were WORSE here than last year! And the other 2 were only marginally slightly better. And only better due to flukes. 1976 all the snow came from a big mid March save. And 2007/8 almost all the snow came from an early December clipper that somehow dropped 7” on only .25 qpf. Otherwise those 2 years were just as awful with virtually no snow here the rest of winter. So history says if we don’t get NAO help it’s likely to be just as bad as last year. Last year wasn’t bad luck. It wasn’t a fluke. It was exactly what a strong Nina pac pattern looks like with a +AO/NAO. (Yes I know it wasn’t a strong Nina but the atmosphere behaved like one so my point is valid).

This part of the equation is where my pessimism lies. We can and have had decent snowfall in a strong Nina. But every instance took high latitude blocking. Not some. Not most EVERY SINGLE one. I can’t stress that enough. Since 1948 Baltimore hasn’t had a single warning level snowfall during either a strong Nina or a central pacific ridge (predominant effect if said Nina) without blocking. Even when we include non Nina years that featured a Central pac ridge I found not one single significant snowfall with that pac pattern that didn’t include blocking. I get the sense some people think we might luck our way into a snowstorm even with a strong pac ridge and +NAO. But history suggests we won’t. That if we do get the currently expected pacific and Atlantic patterns we are just as much toast as we were last year. I’m not saying we won’t get snow. But I’m saying we need one of those two patterns to break our way. Not the whole winter. Look at 2000. We only got the high latitudes to cooperate for a few weeks but that was enough to save us. But if we do get a wall to wall +NAO like we’ve seen for years now...I am not optimistic “luck” saves us.

Simply the fact the Nina is strong doesn’t necessarily mean a torch winter. There have been some cold or somewhat snowy strong Nina’s. However, there are plenty of other factors that in conjunction with a strong Nina aren’t good.

I had 8” here in October 2011

@frd that would bode well for this winter. Still not great as we typically struggle even in a better Nina but it would suggest we might avoid total pac ridge hell like last year. I’m still not sold one way or another. Lots of conflicting tea leaves.

So....

I'll say a prayer for you

so you like to compare a day 5 smoothed ensemble mean to an actual h5 verification?

paging @stormtracker

Yes a negative NAO October is inversely correlated with a -NAO winter. You know what else is inversely correlated with a -NAO winter? EVERYTHING!!! There have only been 3 negative NAO winters in the last 30 years. Anything you run a correlation against a -NAO winter will come back as an inverse relationship simply because the odds of a -NAO winter are so extremely low regardless of whatever else is happening. This is another example of correlation not being the same as causality! But lets look at the data to see if there IS anything meaningful to this October/Winter correlation debate. So first of all there are 2 different ways to calculate winter NAO. Some use D/J/F and some use J/F/M (because that is when the NAO has the most impact on the sensible winter weather). But regardless of which you use there are 3 years...just 2 of those 3 is different in each set. But since we have so few truly negative NAO years lets use all 4. 1996 and 2010 are truly negative years regardless of the way you calculate. 2011 and 2013 flip flop depending on how. 2011 is a neg year if you use D/J/F and 2013 is if you use J/F/M. 3 of the 4 negative NAO winters in the last 30 years came following a negative NAO October. The other came following a neutral NAO October (1996). For what its worth 1996 turned severely negative later in October but numerically it was washed out by positives earlier. So purely statistically -NAO Octobers had a 21% chance of leading to a -NAO winter. All other Octobers had a 6% chance of leading to a -NAO winter! But those numbers are from way too small a sample size to have true statistical significance. And besides...the problem with using the seasonal NAO, besides the fact the base state of the NAO is so positive that you get too rare an occurrence to glean any meaningful correlations, is that we don't need the NAO to be negative for 3 months (or even 1 month) to get snow. We just need some periods of blocking. And sometimes that blocking is bootleg and doesn't even show up in the numerical NAO. And a period of positive can negate a period of negative. Who cares if it snowed right! So...lets look at what we all really care about...snowfall. Averaging the 3 major recording stations in our region (DCA/IAD/BWI) together gives us an average snowfall of 18.1" over the last 30 years. The avg snowfall in the 14 winters following a -NAO October is 21.0" The avg snowfall in the other 16 winters is 15.6" So...we have averaged 5.4" more snowfall following a -NAO October in the last 30 years.

We live in a simulation so

Kinda like your predictions lately

Unfortunately a -NAO in December without PNA or AO help is unlikely to save us. We typically need multiple things to line up to get much snow before Xmas.

Well I haven’t been doing much swimming in the equatorial pacific lately to gather any evidence to refute them.

I agree about 2016. Given the pattern from early January to mid February and then another decent pattern period in March I think it was more bad luck we didn’t get more hits than it was good luck we got one.

See bold part. I’ve been very clear I think this year will very likely be below avg. But how much below I have no gut feeling on. And all it ever takes is for us to get lucky a couple times and suddenly we have a decent snow season even in a crap pattern year. But the chances we get a really awful year similar to last is not 0. And if we get a really strong flat central pac ridge +NAO pattern like all guidance suggests that’s a big problem. Everything in that post I made last December (that Mersky picked a fight over) basically saying we were in big trouble, would apply again. Just because we suffered last year won’t make that pattern any less hostile for snow. I guess my main point is the odds we get an equally awful season to last are a lot higher than some wave to admit. I don’t think that’s Likely how this plays out. But I’m wary that it could.

Probably. But there is a chance this is an epic fail if the result of an actual Nina during a period when we were already experiencing a Nina type pattern due to other factors leads to an Uber ultra Nina pattern. We could get a stable +3-5 std dv pac ridge that floods the conus with Pac puke all winter. It’s not necessarily the most likely outcome but it wouldn’t shock me. On a personal note (and yes I realize this makes me an ass) if we have the choice between some pathetic 6” from several slop storms winter or a complete blank were its 55-65 all winter and we don’t even get a flake I would take the latter just to be able to chuckle at all the “it can’t be worse than last year” posts. Those people obviously aren’t paying attention. It can always be worse. Always.

Having fun

Perfect 50/50 but a lobe rotated around at the exact wrong time and squashed the flow.

True but we did still waste what was a pretty good 3 week period from late November to mid December. We had a few cold rain events that would have been snow in January. Then when we did get a shot of true arctic air into the pattern we missed the one true threat. End result was nothing to show for a pattern that likely would have produced some snow in mid winter! But I’m not saying we can’t snow significantly in December. It sometimes happens. But if we look at the history of the “cold December Nina’s” most were more frustrating than celebratory with mostly minor snows that would leave us feeling unfulfilled when the winter torch comes. I’m purely going by the probabilities based on past results.

Problem is we need so much to go right to cash in much before Xmas. A “decent” pattern is likely to be wasted wrt snowfall. If we only get one mediocre look December is the worst month to get it.

Just shoot me now

Might not even be that much of that, if the euro is right. I don’t think winter is over for us. The climate didn’t suddenly flip a switch since January 2019. We had such high expectations that it’s often overlooked but that was a very “wintery” month. But what seems true to me is while we still get some good periods interspersed with more not do good periods, the not so good are becoming really bad. With warming any less than ideal pattern ends up way too warm. Any forcing that fosters a ridge and we ridge out to Quebec. When it’s not cold it’s REALLY warm! I definitely think we will see another above avg snowfall winter soon (maybe not in time to save a certain someone’s sanity though) and with the increased baroclinicity and moisture we could get a blockbuster winter if we can line enough things up right. But I think really awful years where we get virtually no snow are becoming more common.

At least it would be nice a lot. We probably have very few days with a high below 50 if that’s correct. And likely quite a few 60+ days. And at least we wouldn’t waste time on false hope. Snow would be 500+ miles away not teasing us. We could just accept it won’t snow at all and enjoy an extended October all winter.

Euro is a carbon copy of last winter. Maybe even worse. Ridiculous central pac ridge, AK vortex, raging +NAO.