bluewave

Again, it’s not canceling winter in December to acknowledge that multiple factors are indicating another 40° or warmer December for NYC to EWR. We have seen this time and time again. It fits the pattern of all the 70° Septembers and 60° Octobers. What is actually happening is that December is becoming a fall month and September a summer month.

Have to head to Eurasia if you want to see any real cold this month.

We haven’t had a really cold December in NYC since 1989 which was the last time NYC averaged in the 20s .

The one antidote to a south based block is a +PNA like we got in December 2020. But the more tucked in storm track near ACY due to the south based block produced 40” in Binghamton instead of Boston.

There were two things at work last December. First, the block couldn’t retrograde sufficiently far enough west to boost the PNA like it did in 2010. Second, the Gulf Stream was much warmer last December than in 2010 which probably helped the block build further south than normal.

More like +2 to +3 by mid month with a possible increase after that. And that is against the new warmer 91-20 climate normals. So NYC is on track for another December near or over 40° which used to be much less frequent in the old days.

After seeing how hostile the Pacific has become since 18-19, the phase NAO and AO isn’t as important as it used to be. 20-21 was the only time the NAO and AO was able to coincide with a favorable Pacific. Last winter the Pacific completely muted a monthly -AO value in the -2.5 to -3.0 range which never happened before. So unless we have Pacific on our side, a -NAO and -AO will be going to waste. Hopefully we get get some semblance of a backloaded El Niño this winter with the Pacific backing off during another -AO -NAO interval.

Do you have the link to those higher res charts?

That last VP frame still shows the MJO forcing the MJO 6 region as the RMMs are chasing convection.

Those were much weaker MJOs through the warm phases than we have seen since 15-16 with El Niños. We never saw MJO 4-6 as strong as 15-16 before with such a strong El Nino. In the old days, stronger MJO 4-6 activity was nonexistent in stronger El Niño’s like we have now. There were several posts in this thread a while back that said that the IOD would shut down the MJO 4-6 phases and it would be nothing to worry about. But I pointed out that there would be a rapid rebound in the WPAC SSTs that we are seeing now. https://phys.org/news/2021-04-distinctive-mjo-super-el-nino.html A research group, led by Dr. Wenjun Zhang from the Nanjing University of Information Science and Technology analyzed MJO activity of the super El Niño event during the Northern Hemisphere winter of 2015/16. Observations show that the western Pacific MJO activity was strongly suppressed during the peak phase of the 1982/83 and 1997/98 super El Niño events. However, during the crest of the 2015/16 super El Niño event, western Pacific MJO-related convection was enhanced. "It is apparent that the enhanced western Pacific MJO is mainly related to its sea surface temperature (SST) anomaly distribution and the associated background thermodynamic conditions." said Dr. Zhang. His team's complete research and data are published in Advances in Atmospheric Sciences. When compared to the previous super El Niño events, the warm SST anomaly, or change from average, of the 2015/16 El Niño was located more westward than during the other two extreme seasons. Additionally, no significant cold SST anomaly was detected in the western Pacific. Accordingly, the moisture and air temperature tended to increase in the central-western Pacific during the winter of 2015/16 unlike the previous super El Niño events. This research highlights that climatologists should consider the SST anomaly distribution of super El Niño events for future MJO activity studies.

You have to be careful using those CPC charts which take 3 month averages. The DJF composite often works better for us each month from December to February. The December general MJO 7 chart is warm for us in addition to the December El Niño composite. Plus there is a lag which can take up to a week after passing through 4-6. So the 7 pattern may take up to a week to show up after first entering 7. That’s why we can’t rush the MJO in the warm phases.

We know this month that the El Niño hasn’t been strong enough to shut down forcing in the warmer MJO 4-7 regions. Beyond this month, it will be a wait and see approach. But even if the forcing shifts over closer to the Dateline and stays there, the record SSTs could easily boost the VP anomalies enough to give us a warm Nino pattern. The SSTs in Nino 4 are close to 15-16 right now. So this isn’t some weak modoki signal like years past with much cooler Nino 4 temperatures. The reason I mention a +2 to +3 average departure in the Northeast is because +2.9 has been the average departure in the Northeast last 8 seasons. Plus it’s nearly impossible to pick out an exact departure ahead of time. Just that based on what I am seeing now the, places like NYC and maybe the entire Northeast have a shot at a record 9th warmer than average winter in a row. Notice aI am not taking the leap which you did mentioning permanent. Since I make the distinction between loading the dice for more frequent warmth but variability always holds the potential for a colder winter emerging here and there. It’s just that I am not sure what a colder signal would look like before the season to be confident enough to forecast a cold winter. Our eventual next cold winter May just be a surprise that we have to deconstruct the hoes and why’s when the season is over.

It isn’t about what I feel. It’s what the data has been indicating. Again terms like foreseeable future on your part is taking a leap which I have not advocated for. Talking about the here and now with the record +30C warm pool from the Dateline to the Maritime Continent. So we have to take each winter one at a time. Don’t have any info yet about next winter or the winter after that which match your foreseeable future statement. But we do now that the warmth in those regions has been a significant player over the last decade.

Not a surprise to see the EPS weeklies shift much warmer as they are starting to reflect the MJO 7 slowdown.

A weaker MEI isn’t such a great thing if it just means more forcing in MJO 4-7 or Niña influence like we are seeing now. We just swap out or combine 2 different forcing regions which are warm. Remember, doesn’t have to get anywhere near as warm as 15-16 to still be a warmer winter. We actually probably want a higher MEI to ensure that the warmer MJO 4-6 phases don’t interfere with the usual backloaded El Niño effect later in the winter. Hopefully, something resembling a backloaded El Niño emerges at least for snowfall prospects. Last winter 22-23 had the same average temperatures in the Northeast as 15-16. Both had strong forcing in slightly different warm regions for us. So while it would be tough to have two winters in a row so warm after last year, even half the departures of 22-23 and 15-16 would still be a warmer winter for us. Considering that we went +5 last winter in the Northeast against the warmer 91-20 means the same as the +5 in 15-16. So even a +2 to +3 winter this year would still be mild. So while the warmth in the WPAC to the Dateline is a warm signal, it’s always a wait and see approach what the exact warm departure will be.

Yeah, just pointing out a different evolution than 97-98 doesn’t mean necessarily a colder winter. The 97-98 winter had east based forcing. But we had very strong forcing near the Dateline in 15-16 and it was a warmer winter for us than 97-98. Plus last winter we had very persistent forcing in MJO 4-6 and it too was warmer than 97-98. Not saying this winter will be as warm as 15-16 or 22-23, but if forcing is strong and persistent enough in the MJO 4-7 regions and Nino 4, the risks are warmer than average and not colder. To what extent remains to be seen. We are currently seeing Nino 4 SSTs approach 15-16 levels. And the WPAC warm pool in the MJO 4-7 regions is also the warmest on record for and El Niño.

The November pattern saw the influence of the colder MJO phases for the Northeast. Plus we have had a decadal pattern of colder temperature trends in the Northeast. So two reasons for the colder temperatures in the Northeast. As for the MJO cancelling the whole winter, we just have to take things one step at a time. We know that we get warmer than average patterns when the MJO is in the 4-7 phases. And we know that record warmth in those regions slows the MJO in those phases. I don’t think anyone is canceling winter in December during an El Niño year when El Niños are mostly defined by what happens January 15th to February 28th. But if we continue to see MJO 4-7 activity ,then it could interfere with the typical backloaded El Niño winter response. Hopefully, the forcing focuses more in the regions near the Dateline allowing some semblance of a late winter El Niño pattern. So we are just going to have to be patient since that period is still pretty far out in time to have much confidence about.

Our sensible weather patterns rely heavily on tropical convection which drives the Rossby wave patterns. MJO and ENSO along with increasing marine heatwaves in the tropics and subtropics are another big factor. This understanding has been growing in recent years with numerous papers posted on the MJO slowing down and becoming more amplified in the warmer phases. The main culprit is the expanding WPAC warm pool. This has also been driving the increase in multiyear La Ninas referenced in other papers. We seldom miss an opportunity for warmth when the MJO slows in phases 4-7. There are also papers on favorable snow phases for the Northeast in the MJO 8-1-2 phases. It’s no coincidence that the greatest snowstorm over 30” in spots last March occurred with the strong MJO 8 passage. Unfortunately for us, we have been missing out on MJO 8 windows in recent years as the signal has frequently weakened or stalled before those phases. The MJO can also induce SSWs and cause the NAO to go positive or negative. Several well written and researched papers on that topic also. So as the science progresses, we are understanding the importance how the warming oceans are altering our climate. We also got a primer in recent years on how we need the Pacific on our side even we get a good -NAO -AO pattern. So we really can’t take for granted anymore that the -NAO or -AO will deliver for us without the Pacific backing off and cooperating.

Yeah, it’s been pretty tough waiting for MJO 8s in recent years only to get pushed back or not deliver. We have seen those P7 stalls or loops back missing out on 8. Or the actual MJO 8s like last March with the interior Northeast cashing in on record snows and nothing for the coast. Unfortunately, winters since 18-19 have been defined by unusually hostile Pacific patterns with a raging Pacific Jet into the West Coast dropping the trough in the West.

That is probably rushing things. I think MJO 7 could linger on the VP anomaly charts until the 20th to 25th with such warm waters and forcing near the Dateline. Remember, there is a lag with the MJO and the pattern after it goes through the warm phases. So even if it can make to 8 by Christmas, it could take until early January to get a better pattern. That being said, it’s possible the MJO stalls in 7 and doesn’t make it fully into 8 like we saw several times in recent years. But that won’t be known for sure until we get later into December.

Not much difference since both they both have a warmer than average pattern here. Ridge extending into the Northeast with trough near the SW or near the West Coast. El Nino P 7 December General P 7 December

The RMM charts aren’t telling the whole story. The actual forcing in the 4-7 regions is going to be very robust. This is a warmer than average forcing signal through at least December 20th or 25th. This is why the models keep correcting warmer the closer in time we get. My early guess is that this means another close to 40° or warmer December for NYC.

The wave can’t speed through due to the record +30C SSTs in MJO 7. This is why the VP anomaly charts are more robust than than the RMMs. This is the bias of the of the RMM charts. Even if the RMMs show 8 in the longer range, some forcing still in 7 on the VPs won’t allow a true 8 to develop until the convection there can completely weaken. We see this every December. I think the pattern stays warm than through December 20th or 25th. Not sure about the last week of December yet. But we know from experience that it often takes longer than expected to cool a pattern down after an extended loop through the warmer phases. This is due to the MJO lag effect on the pattern which has been well described.

Exactly. Every December the models do the same thing and we end up lingering longer than expected in the warmer MJO phases. Currently have record SSTs near the MJO 7 region.

This is what we were talking about. The earlier RMM charts had a very weak MJO 4-6 signature while the VP anomaly charts said otherwise. Now the RMMs are showing a more robust MJO 4-7. The GFS often beats the Euro RMMs due to the Euro having issues with the barrier effect and MC convection. My guess is that we could see another stall near 7 which could persist up to the solstice or even Christmas with mild temperatures.