bluewave

The more more amplified snowfall distribution pattern began at Islip in 1994. Prior to that, midrange seasons were much more common. Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Oct 1 to Apr 30 Missing Count 2023-04-30 5.0 0 2022-04-30 37.0 0 2021-04-30 33.5 0 2020-04-30 6.8 0 2019-04-30 12.8 0 2018-04-30 65.9 0 2017-04-30 39.3 0 2016-04-30 41.4 0 2015-04-30 63.7 0 2014-04-30 63.7 0 2013-04-30 46.9 0 2012-04-30 4.7 0 2011-04-30 55.3 0 2010-04-30 53.8 0 2009-04-30 36.2 0 2008-04-30 10.7 0 2007-04-30 9.0 0 2006-04-30 36.0 0 2005-04-30 58.8 0 2004-04-30 41.4 0 2003-04-30 54.6 0 2002-04-30 3.7 1 2001-04-30 38.9 1 2000-04-30 9.0 0 1999-04-30 19.4 0 1998-04-30 2.6 0 1997-04-30 12.4 1 1996-04-30 77.1 0 1995-04-30 5.1 0 1994-04-30 37.1 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Oct 1 to Apr 30 Missing Count 1993-04-30 28.6 0 1992-04-30 13.4 0 1991-04-30 13.8 0 1990-04-30 19.0 0 1989-04-30 19.0 0 1988-04-30 19.5 0 1987-04-30 22.5 0 1986-04-30 15.2 0 1985-04-30 26.9 0 1984-04-30 27.5 0 1983-04-30 31.9 0 1982-04-30 35.4 0 1981-04-30 20.8 0 1980-04-30 9.0 0 1979-04-30 28.1 0 1978-04-30 68.0 0 1977-04-30 28.0 0 1976-04-30 30.2 0 1975-04-30 14.5 0 1974-04-30 34.0 0 1973-04-30 4.5 0 1972-04-30 15.6 0 1971-04-30 18.9 0 1970-04-30 27.0 0 1969-04-30 33.5 0 1968-04-30 22.6 0 1967-04-30 50.8 0 1966-04-30 15.7 0 1965-04-30 39.5 0 1964-04-30 39.7 6

The one thing I have noticed with snowfall at places like Islip is the all or nothing snowfall pattern since the 90s. Either very high years or very low ones. Mid range years have become very rare but were much more common from the 60s to 80s.

When various ensemble members including the OP still have convection lingering near 120E at the end of the run in MJO 5 you know it’s going to be a mild pattern.

Because there is more a chance that they will be correct when the warm signal from the Pacific is so huge.

Yeah, pretty much like clockwork every year. It’s impressive that all 3 ensembles have the familiar Aleutian ridge, Western trough, Eastern ridge pattern near the end of their runs. So the same stagnant pattern of recent years whether it’s an El Niño or La Niña.

Yeah, while the forcing is setting up in a very warm region for the Northeast this month, the waves are progressing eastward. So that enormous December 2015 standing wave which drove those ridiculous departures will be a tough act to follow. Unfortunately, even if we go +2.5 to +5.0 in portions of the Northeast this month like NYC metro, that is against an already much warmer 91-20 climate normals. Plus it will continue the long term trend in December for places like NYC to average over 40° again. Regardless of ENSO state, the Decembers in the Northeast have been one of our fastest warming months.

I know people hear terms like MJO, PDO, El Niño, La Niña, etc and it can get lost in the translation. So a simplified version is using the term marine heatwaves. These are just blobs of much normal than normal ocean temperatures. Unfortunately as the planet warms, most of the heat actually goes into the oceans. So we have many warm blobs in the tropical and subtropical oceans. Since the Pacific is the largest body of water on the planet and lies just west of North America, it exerts a super sized influence on our weather. Thunderstorms gravitate to the areas of warmer waters. These create giant atmospheric waves which influence where the ridges and troughs will set up. Sometimes, we get standing waves that get stuck and drive more extreme patterns here of mostly warmth but on rare occasions cold. Unfortunately, when the Central to Western Pacific basin is much warmer than other regions, the thunderstorms line up there. And thunderstorms in those regions drive warmer patterns for us. It also also been one of the fastest warming regions of the planet. So this is why people have been referring to La Niña background state. When the MJO is active like it is now in the warmer phases, it can take a longer time getting to cooler phases since the Western Pacific is so warm. The MJO numbers are just regions on a map where the thunderstorms are concentrating. Plus when you have convection firing in multi warm regions like we have now, it can come out more as a chord than an individual note. So all these factors in recent years have been conspiring to making the Pacific Jet stronger than average which in term floods North America with mild Pacific air like we are seeing this month and many other recent ones.

The windmill palms have been doing very well on Long Island as long as you wrap them ahead of the winter.

Palm trees will eventually become more common around NYC in coming decades once the January average temperature gets above 36°. https://modernfarmer.com/2018/03/will-climate-change-make-your-hometown-full-of-palm-trees-this-is-literally-a-story-about-palm-trees-its-not-a-leading-question/ But palm trees are popping up in more locations than ever before, and can serve as signposts since they can only grow in certain climates. If you’ve got a palm tree that survives year-round, that tells you something about the local climate. To learn more, researchers from Columbia University’s Lamont-Doherty Earth Observatory took a closer look at the gentle, picturesque palm tree. Lead author Tammo Reichgelt, who has previously studied Antarctic ice melt, looked into the specific requirements of palms, and used records of more than 20,000 fossil palm records to see how palms have spread over time. Palm seedlings, in particular, are extremely sensitive to cold; palms in general cannot survive if the average temperature during the coldest month of the year is lower than 36 degrees Fahrenheit. That need for consistently warm, or at least not consistently cold, weather is why palms are so associated with warm climates; they are hardy plants, widespread and capable of growing in both dry and wet areas in great concentration, but winter knocks them out. That said! Rising temperatures might allow palms to survive in places not ordinarily considered tropical. Let’s take, just for example, Norfolk, Virginia and Greenville, North Carolina. As recently as the 1980s, these cities were too cold to permit palms to survive without a hefty amount of human assistance. Now, though, they’ve breached that climate border; Reichgelt’s research suggests palms could survive there now.

Strong forcing near the Dateline is still phase 7. While we can debate how reliable week 2 models forecasts are, they are not showing a MJO 8 pattern. If we verify that Aleutians ridge and Western Trough with an Eastern Ridge, then it will be reflective of a more MJO 4-7 pattern in mid-December. But Tip just had a very good point about the Pacific Jet in the main El Niño thread. It too could produce a more La Niña-like pattern which is similar to warmer MJO phases pattern. So we could very well see a blend of warmer influences that may not perfectly match any given composite exactly. Just that the lowest common denominator will be a Pacific pattern intent on producing warmth with a very fast jet. Whether we describe it as El Niño or La Niña may not make much difference on the final outcome.

Those RMMs are chasing convection to the east. The actual VP anomaly charts from Euro and GEFS never get the actual forcing past 4-7 for the next few weeks. But this is to be expected with the record +30C SSTs from near the Dateline to the Maritime Continent. Strong forcing near the Dateline is still in the warmer phase 7.

Later starts to winter especially in the Northeast have become the norm.

40°+ Decembers are the opposite the sky is falling for most people off this forum since they can save on heating bills and spend more on the holidays.

So the fist 4 days of December are averaging +5 to +10. The next 4 will average closer to normal. Then we are right back to the 50s by later next week and more days in the +5 to +10 range. So it looks like NYC is on track for another December over 40°. The new 91-20 warmer December average for NYC is 39.1°.

Heavy rains in the Pacific Northwest this time of year are more a La Niña thing. So like in 15-16, the westward lean of the forcing in the MJO 4-7 range resulted in heavier rains displaced further north than usual for an El Nino. So a stronger northern branch of the jet stream. As you mentioned, this is probably why the PNA is struggling to stay positive in early December. Very warm December for much of North America when we have such a strong jet stream off the Pacific and and TPV with the -AO -NAO is located in Eurasia. The competing Nino and Niña-like influences are both warm.

Somewhat similar forcing location this December from the Maritime Continent to the Dateline as we saw during the super El Niño in 2015. So a very westward lean to the forcing for an El Niño December. This is producing the forecast near record atmospheric river to start December into the Pacific Northwest. 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 10 Missing Count 1 2015-12-10 6.33 0 2 2007-12-10 5.69 0 3 1987-12-10 5.05 0 4 1970-12-10 4.68 0 5 1968-12-10 4.37 0 6 1989-12-10 4.10 0 7 1975-12-10 3.89 0 8 1956-12-10 3.46 0 9 1946-12-10 3.22 0

The main difference in 2010 was that the 60° day occurred when the AO was closer to neutral at -0.3 while this year the AO was still -2.5. Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature 2010-11-28 47 2010-11-29 48 2010-11-30 57 2010-12-01 60

Today may be the first 60° day during early December in NYC a few days after the AO going -3.3. It could also be a record for consecutive 50°+ days at the same time. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.daily.ao.nao.pna.aao.gdas.120days.csv

It’s just that the geographic footprint is much smaller with Arctic outbreaks nowadays like with the record 2021 cold in the Plains not making it to the East Coast. So a smaller percentage of the earths surface is able to experience record cold at any given time than in the past. But even if these outbreaks have a smaller aerial coverage, they can be intense in the more limited areas that get them.

Yeah, winter lovers in Europe can rely solely on the -AO and -NAO and don’t have to worry about a hostile Pacific.

The last time was back in 2002. It has been more common to make it to 50° or warmer on Christmas since 2003. Data for December 25 - NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation Snowfall Snow Depth 2022-12-25 28 14 0.00 0.0 0 2021-12-25 52 36 0.16 0.0 0 2020-12-25 61 29 0.92 0.0 0 2019-12-25 47 32 0.00 0.0 0 2018-12-25 40 33 0.00 0.0 0 2017-12-25 38 28 0.23 T 0 2016-12-25 50 36 0.00 0.0 0 2015-12-25 66 57 0.01 0.0 0 2014-12-25 62 44 0.09 0.0 0 2013-12-25 31 19 0.00 0.0 0 2012-12-25 41 32 0.06 0.0 0 2011-12-25 46 31 0.00 0.0 0 2010-12-25 32 25 0.00 0.0 0 2009-12-25 38 33 0.24 0.0 2 2008-12-25 57 33 0.13 0.0 0 2007-12-25 43 35 0.00 0.0 0 2006-12-25 45 39 0.37 0.0 0 2005-12-25 54 39 0.84 0.0 0 2004-12-25 33 25 0.00 0.0 0 2003-12-25 46 33 T 0.0 0 2002-12-25 37 31 1.30 5.0 M

I am not sure if we are ever going to see another March run of snow and cold like from 2013 to 2019 again. It was like someone flipped a switch to warmer in the 2020s. I guess time will tell.

Last December was the warmest on record for a December monthly AO reading of -2.0 or lower in NYC. December 2020 was the warmest on record for a 10" or greater monthly average snowfall and a monthly AO reading from -1.5 to -1.9. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table ……………..AO……..NYC T Dec 22….-2.719….38.5° Dec 10….-2.631….32.6° Dec 09….-3.413….35.9° Dec 05….-2.104….35.3 Dec 00….-2.354….31.1° Dec 95….-2.127….32.4° Dec 76….-2.074….29.9° ……………..AO…….NYC S….NYC T Dec 20…-1.736….10.5”…..39.2° Dec 02….-1.592…12.4”…..36.0°

Yeah, the TPV with this -NAO shifted over to Eurasia leaving a mild Pacific air mass in place across North America. As we found out in recent years, -NAO and -AO patterns can be very mild for us. This isn’t like the old days around 2010 when big -AO and -NAO drops meant cold. I think Don had a great post a while back on how the -AO and -NAO has become warmer for us.

I agree with you on this. It also goes to what I have been saying about the stronger MJO 4-7 with the rapidly warming WPAC as the IOD fades. The reason the models are starting to converge on a warmer solution for December is how strong the MJO 6-7 VP anomalies are forecast to get in the next few weeks. The MJO moving to the Dateline could constructively interfere with the El Niño strengthening it further. Just look at how strong the VP anomalies and WWB are forecast to be. This is why I don’t think the RMM charts will adequately show the strength of this MJO wave. MJO 7 is one of the warmest phases during and El Niño. When you include the lag which take up to 7 days per MJO phase this is why the models have the warmth persisting into so long into mid to late December. The chart below is courtesy of Allsnow who posted it in the NYC forum. My guess is that when the Euro monthly updates on Tuesday, it will have a strong MJO 6-7 look for December.