bluewave

Same crazy jet extension that we got last January.

Yeah, that has been one of my concerns. The previous top 5 wettest first weeks of December in Seattle were mostly La Ninas. I am hoping that we can see some type of backloaded El Niño effect later in the winter. Don’t want to see these Niña-like undertones mess things up. But I reserve my judgment until we get closer to that time. Would like to see some weakening of the Northern branch allowing more of a STJ dominant pattern with some blocking. Time Series Summary for Seattle Tacoma Area, WA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Precipitation Dec 1 to Dec 7 Missing Count 1 2023-12-07 5.78 0 2 2007-12-07 5.68 0 3 1989-12-07 4.06 0 4 1970-12-07 3.83 0 5 1975-12-07 3.63 0

Its a combination of the very strong El Niño and the Maritime Continent MJO phases which excite the East Asian jet leading to the jet extension. That’s why we have been using El Niño MJO composites. So it’s effectively a very strong El Niño with Niña-like influences via the MJO phases. One of the weaknesses of the seasonal models is that they usually can only see the correct ENSO state and not the MJO. So they completely missed the Nina-like record rainfall and strength of the Northern Pacific Jet which lead to the wettest first week on December in the Pacific Northwest. So the +EAMT Eric mentioned is related to the MJO and El Niño interaction. MJO and TorquesFrictional and mountain torques induced by the MJO circulation anomalies are responsible for the angular momentum exchange between the atmosphere and the solid earth. The MJO, Atmospheric Angular Momentum and the Length-of ...

Yeah, it’s just that the colder winter months since the 15-16 super El Niño have become few and far between. I was excited about the cold January 2022 pattern but disappointed for western sections since the lack of a decent -AO kept the best snows near the coast. Late January into February 2021 was also a great pattern. Allsnow did a great job highlighting the December 2020 snowstorm potential from later in November 2020. So not sure why people are giving him so many weenies. He loves a great pattern as much as I do. And will highlight it when it’s actually about to occur. But when we see such a hostile Pacific like we have now it can’t be ignored.

Yeah, it’s just that combining such a strong El Niño with MJO 4-7 phases results in a much warmer December pattern than usual for much of North America that we are seeing this month.

The warming in this case includes the near record SSTs in the western El Niño regions in addition to the warmer Maritime Continent MJO 4-7 phases. My reference to RONI was in the way GaWx was hypothetically using it in his question. Not that RONI wasn’t a thing. But that perhaps the lower RONI values for this event reflected the much warmer SSTs than normal SSTs near the MJO 4-7 regions during such a strong El Niño event. My guess is that the RONI or MEI would be higher if the WPAC was as cool as it was 30 years again and the Nino regions didn’t have competition from the forcing extending further west.

Models are starting to show 5 sigma jet speed departures north Japan even before the main extension later this month. The EAMT that Eric references is a direct result of the MJO in the Maritime Continent phases interacting with the El Niño.

Models are still playing catch up with how warm North America is going to get from mid to late December with a crazy just extension like that. International falls is already around +10 after one of its warmest starts to December. So there is a chance that those double digit departures could be maintained. Not good news for people that like ice fishing up in those areas.

That big +EPO showing up for mid to late December will probably result in numerous stations across the Northern US experiencing yet another top 10 warmest December added to the warm start to the month. The departures especially around International falls may creep close to double digits.

Yeah, I pretty much figured this out. His charts are the only ones in the industry that have the bold color change at the -8 temperature departure from blue to green while maintaining a more subtle orange to darker orange color change +8. This directs your eye to the colder side making the colder departures seem more substantial.

Through the rich get richer mechanism. The WPAC warm pool is one of the regions that sees an increase in tropical convection with warming SSTs. The paper you mentioned discussed subsidence regions in other areas of tropical oceans with warming. The previous papers I posted about the WPAC show increased convection there with rising SSTs and stronger MJO phases. https://www.pnas.org/doi/full/10.1073/pnas.0601798103#:~:text=The “anomalous gross moist stability,because of enhanced moisture convergence. The “anomalous gross moist stability” or “rich-get-richer” mechanism (12) hypothesizes that the upped-ante differential moisture increase will yield increased precipitation within the convection zones because of enhanced moisture convergence. This mechanism also contributes to drying outside the strong convection zones and likewise should yield an approximately fixed spatial pattern whose amplitude grows in time with the tropospheric warming. Among these are drying regions in Central America, the Caribbean, equatorial South America, and along the Atlantic intertropical convergence zone. Precipitation increases tend to occur inside the convection zones, including increases in the Southeast Asian summer monsoon. Increased precipitation also occurs in the equatorial Pacific, associated with changes in the dynamics of the equatorial cold tongue and local sea-surface temperature increase (15–18).

Yeah, that would be one I would love to experience also from the 1800s. My number one pick from the 1700s would be NY Harbor freezing over in 1780. My guess is that January 1780 averaged around 15°-17° in NYC. The coldest recorded month since the late 1800s in NYC was Feb 34° at 19.9°. https://www.nytimes.com/2002/12/05/opinion/a-cold-snap.html In the winter of 1779-1780, New York Harbor lay frozen for five weeks. It was possible to walk to Staten Island. The Hudson River was a broken pavement of ice, and by spring nearly every tree in the city, and much of its furniture, had been burned for heat. Those were the days before official weather records were kept, so no one knows exactly how cold that terrible winter was, when even the Chesapeake froze over.

My greatest weather disappointment was missing the Nemo 50DBZ jackpot zone with 6”+ per hour rates and 30-40”totals. I would gladly take 3 winters in a row like 2001-2002 for just one storm experience like that.

I understand the sentiment. So while we can’t control the lack of snow, we can have control over how we respond to it. Keeping expectations low in patterns like this can help. I find some of the biggest weather disappointments of the past occurred at times when expectations were raised unreasonably high. Not when difficult patterns gave clues so the lack of snow was expected.

I don’t understand why the terms like positive and negative keep getting thrown around when discussing weather model output and patterns that are outside our control to influence.

Maybe you didn’t read what you just posted since it actually bolsters my argument. The Western Pacific regions are warming faster so that is where the convection is focusing competing with the El Niño. My reference to RONI was in a different context. The poster I was responding to was implying that the RONI could reduce the forcing there.

Rinse and repeat from the extended EPS. Dec 11-18 Dec 18-25 Dec 25-01

https://www.nature.com/articles/s41586-019-1764-4 Twofold expansion of the Indo-Pacific warm pool warps the MJO life cycle M. K. Roxy, Panini Dasgupta, Michael J. McPhaden, Tamaki Suematsu, Chidong Zhang & Daehyun Kim Nature volume 575, pages 647–651 (2019)Cite this article 12k Accesses 91 Citations 498 Altmetric Metrics details Abstract The Madden–Julian Oscillation (MJO) is the most dominant mode of subseasonal variability in the tropics, characterized by an eastward-moving band of rain clouds. The MJO modulates the El Niño Southern Oscillation1, tropical cyclones2,3 and the monsoons4,5,6,7,8,9,10, and contributes to severe weather events over Asia, Australia, Africa, Europe and the Americas. MJO events travel a distance of 12,000–20,000 km across the tropical oceans, covering a region that has been warming during the twentieth and early twenty-first centuries in response to increased anthropogenic emissions of greenhouse gases11, and is projected to warm further. However, the impact of this warming on the MJO life cycle is largely unknown. Here we show that rapid warming over the tropical oceans during 1981–2018 has warped the MJO life cycle, with its residence time decreasing over the Indian Ocean by 3–4 days, and increasing over the Indo-Pacific Maritime Continent by 5–6 days. We find that these changes in the MJO life cycle are associated with a twofold expansion of the Indo-Pacific warm pool, the largest expanse of the warmest ocean temperatures on Earth. The warm pool has been expanding on average by 2.3 × 105 km2 (the size of Washington State) per year during 1900–2018 and at an accelerated average rate of 4 × 105 km2(the size of California) per year during 1981–2018. The changes in the Indo-Pacific warm pool and the MJO are related to increased rainfall over southeast Asia, northern Australia, Southwest Africa and the Amazon, and drying over the west coast of the United States and Ecuador.

It really does since the convection doesn’t care about concepts like RONI .

You know it’s a tough pattern when even the usually snowy long range GFS is giving us much fantasy snow than last December.

It is a big deal if the record SSTs are anywhere in the MJO 4-7 regions with the actual SSTs near +30C.

You have to use the VP anomaly charts for a bigger picture of the forcing going on as it can be underestimated by the RMMs charts. Brad Harvey is using too small a SST zone for it to be relevant to the totality of the WPAC warm pool. One SST region near the MJO 4-7 forcing regions just experienced the highest November SSTs on record.

Pretty much par for the course with the rapidly expanding WPAC warm pool holding convection longer in the warmer MJO phases. So we have been going through some version of this most of this decade in December. Long range guidance always underestimates the intensity of the MJO 4-7 phases. Then it tries to weaken convection too soon and the warmth lingers longer than expected.

Yeah, we take what we can get in the post Boxing Day Blizzard December era. I don’t think we realize how spoiled we got from 2000 to 2010. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Dec Season Mean 2.6 2.6 2023 0.0 0.0 2022 T T 2021 0.2 0.2 2020 10.5 10.5 2019 2.5 2.5 2018 T T 2017 7.7 7.7 2016 3.2 3.2 2015 T T 2014 1.0 1.0 2013 8.6 8.6 2012 0.4 0.4 2011 0.0 0.0 Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Dec Season Mean 8.9 8.9 2010 20.1 20.1 2009 12.4 12.4 2008 6.0 6.0 2007 2.9 2.9 2006 0.0 0.0 2005 9.7 9.7 2004 3.0 3.0 2003 19.8 19.8 2002 11.0 11.0 2001 T T 2000 13.4 13.4