griteater

Been thinking about this in recent days...regardless if the Euro shows warm and snowless or winter storms, I suspect it will be the better model in this pattern. It's already been better with the stratospheric evolution and should be better with the stratosphere - troposphere coupling. Also, it historically does better with larger global features like high latitude blocking. Note from Simon Lee on Twitter: "GEFS & CFSv2 have 64 vertical levels, while ECMWF's ensemble has 91 and more of those are in the stratosphere (38 above 100 hPa vs. 24 in CFS). So, I anticipate ECMWF is on the right lines, as models with greater vertical resolution perform better"

Mid Jan and on IMO, yes

Euro Weeklies trend loop...7-day avg for Jan 14-21...last 6 model runs including today's

Still good with this. Agree with @CAD_Wedge_NC that chances for a big one are elevated. But it's' going to take a little time. The Pacific pattern is straight awful the first 10 to 12 days of Jan, then it should gradually improve. We have what looks to be a strong -NAO episode coming in 8-10 days. Meanwhile, we have a legit, downwelling SSW (strat warming) on the doorstep - Euro is locked in on Jan 5 which is earlier than I anticipated would happen. In addition, the lower stratosphere is already in a very weakened state. Research from Simon Lee states that the Arctic High regime (-AO / -NAO) is 7 times more likely to occur when the lower stratosphere is in a weakened state, and the SSW will only reinforce the weakness. Thinking we may see something like a heavy blocking period here in early to mid-Jan, then a bit of a relax period at some point, followed by another heavy blocking period. We should see an improving Pacific pattern mid-Jan and after, though suspect it will be variable. Good luck to all

The whining thread will be hot and heavy for sure. Hopeful that we can see a better pattern emerge or in sight by mid-Jan. The Greenland blocking and Strat Warming (and likely official SSW) are things we haven't see much of at all in the past 10 years, so that is interesting to see. Hopefully, that will be something that sticks around for much of the winter (at least off and on), and we get into a better Pac pattern down the road. We are going to need a little GNR Patience though I think, as it may take some weeks.

Yeah, the Pac side is just essential for the cold air. We can't have a bad Pac side. I guess it is something like this (thinking out loud, ha)...For number of winter storms / winter storm threats, we've gotta have the Pac side. The Atlantic side then gives you a better chance at having higher quality storm features like 50/50 lows, surface highs that don't race off the NE coast, sfc highs with CAD, suppressed 500mb wave track, amplifying and slower moving waves (storms)

NOAA CPC is predicting a new MJO event will emerge over the Indian Ocean in Week 2. It would then move east, but we would have to see with how much amplitude. Strat warming should help with propagation if it does indeed form. See the MJO Weekly Update - https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.pdf

^ I gave some thoughts regarding the culprit for the problems with the Pacific pattern in a thread here: https://twitter.com/griteater/status/1342941989696905218

As good a retrograding Greenland block as we've seen in 10 years getting ruined simultaneously by an awful Pacific pattern. These are in complete opposition to one another in terms of what we are looking for.

Canadian has the same setup as the GFS, but after the wave digs in TX, it gets squashed/weakened as it moves east so there is no storm east of TX/LA

The GFS keeps trying with the storm in early Jan

raindance - I've never picked up on that, but you are correct on the sign difference there. This page indicates that the "EP/NP index replaces the old EP index which is no longer maintained by CPC" - https://psl.noaa.gov/data/climateindices/list/ -EPO means ridging over Alaska. Here is a site for the EPO. It gives a definition for the EPO, but it looks like the data links are broken - https://psl.noaa.gov/data/timeseries/daily/EPO/ Here is an EPO site that was constructed by Alan Marinaro, but the data hasn't been updated since 2016 - http://www.wxmidwest.com/epo/ Back to the EP/NP Index, here is a composite of all January's in which the EP/NP Index was +1.00 or higher. Basically, it looks just like the EPO, but with reversed sign. In this case, +EP/NP Index means ridging over Alaska

@Isotherm - thanks for posting your updates in here. I hope you will continue to do so. Yeah, I'm not sure what to make of this big incoming +EAMT. Following the descent of the Siberian High, I would expect to see a strong low kick out into the northwest Pacific, with a downstream large -EPO and/or +PNA ridge...but the current modeling acts like it wants to somewhat flood AK with low pressure. I wasn't sure if that's a situation where models will correct in time, or if the large nature of the +EAMT could lead to that type of result. I'd also expect to see solid split flow develop following the development of the -EPO/+PNA ridge. Do you recall other scenarios / analogs with this type of large Siberian High descent?

Yeah I just chose 09/30 there because that was the date from the total snow map that you posted

Snowfall Percent of Mean from 09/30 to 12/01

raindance - you can get NAO data back to 1899 from climate data guide: https://climatedataguide.ucar.edu/sites/default/files/nao_pc_monthly.txt https://climatedataguide.ucar.edu/climate-data/hurrell-north-atlantic-oscillation-nao-index-pc-based

Iso - good read as usual. Thanks for continuing to post these (same with others posting outlooks).

Posted my winter outlook here: https://www.americanwx.com/bb/topic/54042-griteaters-winter-outlook-20-21/

It's likely that more steady positive SOI numbers will return once this MJO wave moves back into the La Nina like phases (3-4-5)

^ Raindance - it's just one piece of the puzzle. You need to be able to predict whether the North Pac ridge will be poleward (North) or suppressed (South)...and whether it will be biased to the east or to the west (from a seasonal standpoint). You also need to be able to predict what the AO/NAO are going to do. All of that impacts the forecast. For example, for 16-17, if you could forecast that the N Pac ridge was going to be biased to the NW and that the AO/NAO were going to be positive, you'd get the general idea correct of cool in the PNW and warm in the eastern half of the U.S.

In the paper from Zhang et al., they categorized Ninas as Central Pacific when the max cool anomaly stayed along 160W from late summer thru winter, whereas the East Pacific and Mixed Ninas started with the max cool anomaly along 110 to 120W before migrating west during the winter - https://link.springer.com/article/10.1007%2Fs00382-014-2155-z The current Nina aligns more with the East Pacific or Mixed versions

By the way, for classifying ENSO strength in terms of SSTs, I've always liked how it is done by Jan Null - https://ggweather.com/enso/oni.htm So, in order for the La Nina to be classified as Strong, 3 consecutive tri-monthly ONI readings would have to be -1.5 or lower....e.g. SON / OND / NDJ would each have to be -1.5 or lower (or OND / NDJ / DJF)

Nino 3.4 has fallen to -1.72 on this daily data. It's been a steady decline thru October

Tip - you have a lot to unpack here, haha. IMO, the QBO to La Nina/Cool ENSO relationship is one of the better winter seasonal forecast correlations that exists. In a nutshell, when the QBO is positive at 50mb, this favors a more poleward North Pac ridge. When the QBO is negative at 50mb, this favors a more suppressed North Pac ridge. This correlation has been successful in 21 of 29 cases (72%). For cases where the QBO was positive, it has been successful in 14 of 18 cases (78%). 2 years were thrown out (83-84 and 85-86) because the Jul-Oct Global AAM prior to the winter was positive, which is one indicator that the La Nina is not very well coupled with the atmosphere. It is very rare to see the Jul-Oct Global AAM positive leading into a La Nina / Cool ENSO winter...the avg AAM is solidly negative in recent months. For QBO designation I like using the Free Univ of Berlin QBO chart to eyeball the QBO progression for each winter along 50mb, during the period Nov-Feb - https://www.geo.fu-berlin.de/met/ag/strat/produkte/qbo/qbo_wind_pdf.pdf. For the cases that failed, there was no bias as to whether the QBO was rising or falling, or whether the amplitude of the QBO was high or low. The key differentiating factor was whether the QBO was positive or negative. HM previously had a detailed post on his blog about this correlation (from 2012), but his blog is no longer active / posts are no longer visible...but here is what I believe is at least part of the science behind the correlation. During the +QBO (Westerly), there are warm anomalies in the lower stratosphere along the equator with cool anomalies off equator into the subtropics. The higher tropopause height off equator allows for deeper, more robust tropical convection there (compared to normal) - this is termed the "QBO Induced Meridional Circulation" Images below contain OLR for a mix of weak to strong La Ninas. On the left are -QBO Ninas. +QBO Ninas on the right. We can see the +QBO composite showing enhanced off-equator convection in the 10N to 25N zone. Note: on these images, the color scheme is reversed from the typical OLR composites...that is, the warm colors are showing -OLR anomalies (enhanced convection), with the cool colors showing +OLR anomalies (reduced convection). It's my belief that the enhanced off-equator convection aids more poleward ridge building in the North Pacific via the typical process (image below from: https://blog.timesunion.com/weather/how-el-nino-influences-our-weather/1247/) Looking at daily Singapore sounding data, we can see that the +QBO is behaving as expected this fall as temperatures in the lower stratosphere along the equator are showing plus anomalies (far right side of image) Also, we can see in this loop of 50mb temperatures, the warm anomalies along the equator, with the cool anomalies off equator Here are composites of -QBO / "South" / Suppressed North Pacific Ridge winters VS. +QBO / "North" / Poleward North Pacific Ridge winters during La Nina / Cool ENSO (I used SON to JFM averaged ONI of -0.20 or lower for selection of the years) Here is the +QBO "North" composite with trends noted for years since 1990 Having said all of that, there are years where the correlation doesn't work. 2 reasons can be: 1) The lower stratospheric temperature profile in the tropics and subtropics doesn't match the QBO Induced Meridional Circulation pattern discussed earlier, and 2) The polar vortex / AO / NAO are overly positive/strong and zonal flow is too strong to allow development of poleward ridges in the mean pattern. Lastly, there were 2 other things you mentioned that I wanted to touch on. One was the interrupted QBO cycle. Indeed, one interruption occurred in the winter of 15-16 and the other occurred last winter. The QBO does however appear to be back to a more typical cycle (at least for now). We can see the tan colors here showing the +QBO stretched out from roughly 20mb down to 70mb on the far right You also mentioned utilizing the QBO in terms of its movement thru the QBO cycle/progression. Sam Lillo has done work in this arena. Here is one of his images showing the occurrence of strat vortex weakening events at various times in the QBO cycle. You can see at various points in the cycle where there is preference for early winter vs. late winter weakening events. My guess is that we are currently somewhere between W30 to W50 on this image.

Yeah it looks like that page was taken down. You can do a google image search on madus weather teleconnections and it will show some of those teleconnection pages scattered throughout the internet where folks have pasted them into a blog, etc., like here - https://dcstorms.com/2019/01/06/capital-weather-teleconnections-mjo-indicate-a-return-to-winter-january-2019/