Bob Chill

Had a hunch the flip to warm will be delayed. Very impressive high latitude AN height/pressure pattern going on. A setup that typically fights back before caving. Def not the same pattern that displaced the tpv during 13-15 seasons. The longer it holds on the better the odds of a recurrence after it takes a break. Starting Dec with an anomalous -AO would be a solid reason to turn optimistic for early winter snowfall.

It does and it gets on my nerves. My fall leaf clearing process includes a prelim blow and mow in late Oct so my grass is nice and tight for when the big drop happens. Wind blows my leaves into my neighbors' yards when it works. A warm stretch in early nov fooks up my system by causing the grass to grow an inch and leaves get trapped in my yard. Very annoying some years.

Definitely try and time an upslope event. It's a different world worth the 2.5hr drive and then some. Upslope isn't as good as a synoptic event in our yards locally but it's pretty awesome having convective snow squalls off and on for days. Last time I timed a trip up there it snowed 2-4" of high ratio every day for 4 straight days. The crunchy dry packed snow on the roads reminds me quite a bit of my years in CO.

@PSU sooo.... you and I basically agree top down on everything leading in. So the next topic of discussion is since we both agree on what we see right now, what is the most likely culprit to destroy our hopes and dreams and end up having a dead rat? I suppose the answer is consolidated in one single place... Iso's seasonal outlook. LoL

You guys keep hearing me talk about a +PDO so here's a quick visual post to make it easier to understand if you're not familiar with the PDO region and what is good and bad etc... Here's a textbook +PDO. Nino years almost always feature a +PDO because warm enso coincides with BN SSTs in the werstern side of the north Pacific. However, a +PDO during enso neutral years is not as common and it's a net positive as shown in my previous post with enso neutral/+PDO years. Right now the npac basin is right in between a + & -PDO. Basically ambiguous. The blue circle is the area to watch. There's plenty of work to do as the + SSTA's near Japan are pretty damn warm. But the trend in general since Sept is slow cooling of the region. The eastern side of the NPac already looks good. Here's why I think the trend towards a potential +PDO will continue. Over the next 2 weeks the height patterns and surface temps are prog'd to be below normal for most of the period in the west NPac at the same time the PNA will be turning positive. Between the PNA ridge in the east and the persistent troughing in the west, it's reasonable to expect SSTs to continue to cool in the western region and warm near the coast of north america. 2 weeks isn't long enough magically fix everything and have a classic +PDO. It takes a lot of energy to bully ocean SSTs. It is encouraging seeing a good longwave pattern in the Pac for the next few weeks and just hope it continues all Nov into Dec. If it does then my guess is the early winter pattern may be showing its hand in a good way.

@PSU It's a tough year with no "easy" signal basically anywhere. Everything from top to bottom looks right in between good and bad to my eyes.

You must be looking in the mirror

TLDR: way too early to expect or rule out any outcome this winter If you look at all current data objectively the sum points towards a rather boring winter. Nothing screams cold and/or snow and everything is at least whispering to not expect great things. But it's Nov 8th and the next 7 weeks or so is the window that most often throws a curveball at seasonal forecasters. Just as lack of blocking has baffled many over the last 5+ years, who's to say that a roaring -AO doesn't lock in during Dec/Jan? Or the Pac jet base state won't setup highway lanes that roll up and over the top of a PNA ridge and dig down to the gulf? These things have proven to be extremely difficult to forecast with any accuracy at 1+ month leads during enso neutral years. Dec is notorious for having a persistent longwave pattern upstream. And it's shown us many times that the persistent pattern in Dec likes to repeat throughout at least a portion of met winter. Do I think I know what kind of persistent pattern may set up in Dec? Nope, I really have no thoughts on that at all yet but I'll be watching things close AF as we roll through the second half of Nov. Dec could be quite variable with no recurring theme or it could tip winter's hand. Won't be too long before some clarity shows up there. Sometimes it's more of a timing issue versus a blown seasonal forecast. Like last year when it finally "got right" it was simply too late. Think about how bad d10-15 ensembles and CFA/EPS weeklies did last year? They ALL kept showing the same good thing run after run but the atmosphere didn't oblige until it was too late. The unexpected pac jet pattern in Dec-Jan basically committed felony larceny for 8+ straight weeks. That took every single wx enthusiast, professional, and weather supercomputer by surprise. What if the opposite happens this year and we "luck into" a nice longwave pattern even though the signs and data says we shouldn't? How can you confidently rule that out considering how many "surprises" winter has delivered over the years? I've only just recently started to see things that may break in our favor but my expectations are still pretty low and I'm fully prepared for an underwhelming snow season. The most promising thing that's happening in real time is the AO. Ens forecast over the next 2 weeks take it as low as -4. I have to dig around my files to find it but I did do a Nov AO analysis not too long ago. Having a mean -AO of at least 1sd below normal in Nov does correlate with a -AO during Dec and Jan. I have no idea if this winter will be blocky or not but seeing a pretty stout -AO in Nov is never a bad thing. If the PDO region starts setting up a +PDO as we close the month out that's not a bad thing either.

I don't have much to say about "Victoria mode" as I've never paid any mind to it. Right now the Pac basin is ambiguous irt the PDO. If this was say mid Dec or later I wouldn't like what I see at all. However, this transition time of year can drop some clues and what I'm seeing over the next several weeks is a favorable pattern from Japan to the central pac basin to shuffle SSTAs around towards +PDO. Based on the warm anoms in the eastern npac near Japan, there's a good bit of work to do to get things looking more promising. Next couple weeks look decent but it's going to take more than a couple weeks to get a legit +PDO.

True but I was mostly thinking about the type of setup more than Nov being hostile in general. We'd struggle with this identical setup in Jan/Feb so Nov makes it that much harder. I will say the cold front itself is pretty exceptional for Nov. Record lows might get broken. Getting a wave with a narrow 100mi stripe of precip to line up right is asking a lot. When I first saw this pop up on guidance my first thought was the precip will most likely roll through as rain before the front. We can't write it off yet as fast moving shortwaves like this typically aren't modeled with accuracy until 72 hours or so. It could pop back up at any time but once we get to 72 hours or less it needs to be either really close or overhead on guidance.

Pretty much what I've been expecting unfortunately. It's exceptionally hard to defy Nov climo.

That's if we survive that long. We may be down to half staff before the end of Dec. Iso's forecast already took out the weak. I'm all in until I'm out

Don't worry about the NAO at long leads. The domain space is very small and slight variations in the upper level pattern greatly affect the calculated NAO. The predictive skill of the NAO beyond just 1-2 weeks is terrible. The AO is different as it covers MUCH more real estate. Solar mins generally mean better chances of a -AO. Sometimes that goes hand in hand with the NAO and other times they are completely disconnected. If you pick 1 index to focus on definitely stick with the AO and nothing else. It has the highest correlation (by far) as to how much or little snow the mid atlantic receives on average. Right now the AO looks favorable through most of Nov. If that carries into Dec then we can start drawing some conclusions as a Dec -AO of -1.2 or lower has like an 80% predictive skill of above normal snow. The NAO acts more like a traffic cop and is much more unpredictable and volatile. Our biggest storms happen with a -NAO relaxing towards neutral or positive (Archambault event). That's for bigger storms though. The AO controls our snow chances in general. The only thing that can easily override a -AO is a tragic Pacific. 2012 is a great example of the way we can fail even with a favorable AO. If you want to focus on the NAO then you want it to be very volatile with periods of deep negative followed by relaxations repeatedly. A stout -NAO park in place kinda sucks here. The SE loves it but not us. The AO is different in that we just want a stable -AO for as long as possible.

agreed. Especially early on as wavelengths are still transitioning. We can get some nasty warmth/ridging in Dec. It gets much harder in Jan/Feb but Dec has no problem turning on the heater. Dec 2013 hit 80 right? I remember it being insanely warm for a time. Had the windows open and it was too hot in the house.

One thing we prob all suspect and agree on is a stout relaxation of the current very anomalous Nov cold is coming. I'm sure either late Nov or early Dec ends up being pretty warm for a time. Which is totally normal and happens like every single year and stuff. lol Dec 2013 was interesting. Cold early, down right hot, and then the hammer. I don't mind December having a sig warm period but I do mind it when it's all the eye can see for 2, 3, or even 4 weeks. I really have no idea what's in store for Dec but I know what to look for. If Dec goes end up cold or at least has a decent duration period of real winter wx in the east then some of the seasonal forecasts aren't going to look so good.

@frd That JMA height plot implies favorable conditions to continue pushing the pdo positive. Iso's winter forecast is extremely well thought out and articulated but imho the potential trouble spot is his -pdo influence/forecast. We'll know in a month or 2...

We've had quite a few of these types of deals over the last 4 winters. There are numerous threads started with d5 waves in a progressive pattern that ended up being no event at all. Lol

Each year always has a bit of its own personality regardless of all the good and bad signals. Since our winters are so short it can be devastating to end up with a hostile pattern for 4-6 weeks. I'd like to think our base state features a pattern that isn't a shutout in general. I really hate when there's literally no chance for weeks on end. The most reliable indicator for good snowfall (other than enso) is a Dec -AO of at least -1.0 or lower. Data shows that -1.2 or lower is like an 80% chance of at or above snowfall. The streak of big +AOs has to end eventually. We haven't had a neg AO in Dec since 2012 and it didn't even matter that year because the Pac decimated our hopes and dreams. All the -AO did was deliver Pac maritime air out of Canada. lol.

That's interesting... My guess is the simple fact that temps are warmer and we're losing on the margins. Could be decrease in seasonal precip but I doubt that's the case.

Basic stats on enso neutral winters favor sub climo snowfall so that may be tough to overcome. The stark reality here is all ENSO winters favor below normal snowfall except for a mod Nino. I'm not thinking this will be a big winter (yet) although any winter can work out. What worried me in early fall was the potential for another hostile Pac year and god knows when we ever get blocking help again... That risk appears to be declining. Based on everything I've looked at it's looking more and more like we won't have a warm door to door winter and I'm starting to like what I see in the npac. I don't make seasonal forecasts but gun to head guess... 10-15" at DCA and somewhere around 20" at places like IAD is what I think is most likely. With the exception of mod Ninos I never have any confidence in anything until Dec starts. That's typically the earliest we'll get a glimpse at what might be the predominant pattern in the conus. Cruising towards mid Novie and not seeing hostile patterns or glaring problems is never a bad thing. Nov can be brutally deceptive though. If early Dec features a displaced trop PV and extensive ridging centered around the west coast of NA then I'll start to get a little more excited about the potential. The only thing that would deflate me is a strong consolidated +AO to kick off Dec. That's an omen that has proven to be a reliable indication that we're in for some trouble. Sure, we can use 13-14 as an example of defying that type of problem but that year was a statistical anomaly on so many levels...

I'm just warming up to the idea that this winter may not be a disaster. When I looked at things in Sept I wasn't impressed at all and figured a dud was on tap. Now that we're transitioning into colder climo it's nice to see there are some things potentially breaking in our favor. Should be fun around here when this impressive Nov cold pattern breaks down and a couple weeks of mild weather shows up on guidance.

@frd From what I've watched over the years, a -NAO is most important during Dec so if we're going to get a good blocking month let it be December. Next best is Feb. Blocking in Jan can be an easy recipe for dry and cold (SE loves this setup though). Also, if the winter's base state is a coupled PNA/EPO ridge then we probably don't want a strong -NAO at any time. SNE definitely doesn't. As always it's a balance. I'd prefer many periods of the -NAO pressing and retreating but what I prefer doesn't mean jack. lol

This setup is very similar to a number of events in 2013-14 and the one thing that is really interesting is the level of cold behind this front. That's like once in 20 year kind of stuff for the first half of November. Because the cold appears to be legit there's a case that can be made for a real shot at snow next week. What I'd like to see is the front amplify further allowing the trailing wave to lag and not run hot on the heels of the front itself. Maybe 12z leans that way...

Personally, I'm not enthused by the setup next week. It's one thing when cold HP is established but gets really tricky banking on an early season arctic front to clear in time AND have a perfectly timed wave develop and run the boundary while we're on the cold side. Climo will fight this type of event tooth and nail. I'm not saying I don't think there's a chance just that I think climo will prevail and the reality will be rain/cold front/cold dry. We'll see.

Long range forecasting outside of easy enso years has been pretty abysmal both in model land and met or enthusiast forecasts for years (I know u know this well). It usually ends up looking something like this at the end of the season: "I got the fill in the blank correct BUT....". But = the atmosphere does what it does best and does a lot of things that nobody predicted and in many cases it was never even discussed at all. I'm not trying to insult anyone because I really appreciate the effort from the skilled seasonal forecasters. It's just not possible to consistently predict weather months in advance unless enso is the primary driver so skill is at least part luck and sometimes mostly luck. I could bat .750 in our area just by saying above normal temps and below normal snow every single winter. That's not really skill. It's basic climo and sticking with simple climo is boring but effective.