bluewave

It’s interesting that the rapid warming of the North Pacific could be contributing to the 2012 minimum not being surpassed due to a weakening of the AD since then. Article Open access Published: 18 November 2025 Decelerated Arctic Sea ice loss triggered by accelerated North Pacific warming over the past decade https://www.nature.com/articles/s43247-025-02882-1 This study offers fresh insights into the mechanisms behind the decelerating decline of Arctic sea ice from 2007 to 2024. We demonstrate that an SST trend in the North Pacific excites a Rossby wavetrain that propagates into the Arctic, driving a downward trend in the summertime Arctic Dipole (AD) index (−0.1 year⁻¹, p < 0.02). This shift induces anomalous surface wind patterns and colder air temperatures, fostering sea ice increases in the central Arctic Ocean near 180 °W (region 1) and the Canadian Arctic Archipelago (region 2), with trends of 0.4% year−¹ and 1.1% year−¹, respectively. These regional gains offset losses elsewhere, contributing to the observed slowdown in overall Arctic sea ice decline. Previous studies have documented the upward trend in September Arctic sea ice extent since 200734,35,36, yet its underlying cause remains unresolved. Our findings complement prior research on sea ice outflow11 and ocean heat transport13, while not diminishing their importance. For instance, southerly wind anomalies linked to increased sea ice in regions 1 and 2 (Fig. 2c, d) may reduce outflow through the Fram Strait, while northerly winds near the North Pole transport ice into region 1, enhancing its growth. Contrary to reports of an increasing AD index over the 2007–2024 period relative to the 1992–2006 period13, we attribute the deceleration to a declining summertime AD index, driven by North Pacific SST warming, which agrees with previous studies37,38. This warming, potentially tied to rising greenhouse gas emissions, merits further investigation to pinpoint its origins.

Colder start to December fits within the long term trend since 1991. NYC average temperatures have only risen +0.7° in NYC from December 1st to 16th. But the December 17th to 31st average temperatures over the same period have increased by +4.6°. This matches the streak of 55°+ days every year since 2011 around NYC from the 17th to 25th. So my guess is that the warmest departures we see this month will occur after the 16th. Time Series Summary for NY CITY CENTRAL PARK, NY highest temperature December 17th through 25th since 2011 Click column heading to sort ascending, click again to sort descending. 2024-12-25 59 0 2023-12-25 62 0 2022-12-25 58 0 2021-12-25 60 0 2020-12-25 61 0 2019-12-25 57 0 2018-12-25 61 0 2017-12-25 55 0 2016-12-25 58 0 2015-12-25 72 0 2014-12-25 62 0 2013-12-25 71 0 2012-12-25 56 0 2011-12-25 62 0

Yeah, the number of 1” snowcover days at ISP the last 7 seasons has been roughly half that of the colder and snowier 70s and 80s at 11 days vs 21 days. Monthly Number of Days Snow Depth >= 1 for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean 0 0 2 3 6 0 0 11 2024-2025 0 0 1 7 5 0 0 13 2023-2024 0 0 0 5 6 0 0 11 2022-2023 0 0 0 0 1 1 0 2 2021-2022 0 0 0 6 9 0 0 15 2020-2021 0 0 7 0 23 0 0 30 2019-2020 0 0 3 0 0 0 0 3 2018-2019 0 0 0 1 1 2 0 4 Monthly Number of Days Snow Depth >= 1 for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean 0 0 2 10 6 2 0 21 1988-1989 0 0 7 2 3 3 0 15 1987-1988 0 1 3 15 0 2 0 21 1986-1987 0 0 1 12 10 1 0 24 1985-1986 0 0 3 4 13 0 0 20 1984-1985 0 0 1 13 10 0 0 24 1983-1984 0 0 1 15 0 6 0 22 1982-1983 0 0 4 3 8 0 1 16 1981-1982 0 0 0 19 0 0 4 23 1980-1981 0 0 1 22 0 2 0 25 1979-1980 0 0 1 3 1 1 0 6 1978-1979 0 0 0 3 14 0 0 17 1977-1978 0 0 0 13 22 18 0 53 1976-1977 0 0 6 23 7 0 0 36 1975-1976 0 0 5 8 7 2 0 22 1974-1975 0 0 0 1 5 1 0 7 1973-1974 0 0 0 14 10 1 0 25 1972-1973 0 0 0 0 2 0 0 2 1971-1972 0 0 0 3 8 1 0 12 1970-1971 0 0 5 11 1 0 1 18 1969-1970 0 0 7 19 6 2 0 34

Earliest 20° reading in NYC since the 2007-2008 La Niña. But the snowfall outcome was lower this time around. We finally got some cold into Eastern Canada which has been lacking in recent years. Dec 5, 6:51 am 21 2 43 11 ENE 9 10.00 CLR 1027.20 30.18 30.35 24 20 Climatological Data for NY CITY CENTRAL PARK, NY - December 2007 Click column heading to sort ascending, click again to sort descending. 2007-12-01 38 25 31.5 -11.7 33 0 0.00 0.0 0 2007-12-02 36 20 28.0 -14.9 37 0 0.33 1.4 0 2007-12-03 47 32 39.5 -3.1 25 0 0.31 T 0 2007-12-04 34 28 31.0 -11.3 34 0 0.00 0.0 0 2007-12-05 33 28 30.5 -11.5 34 0 0.02 0.3 0 2007-12-06 33 21 27.0 -14.7 38 0 0.00 0.0 T 2007-12-07 35 28 31.5 -9.9 33 0 T T 0

This source shows the strongest tendency decline in months. Makes sense since we are seeing a big reversal from all the +PNA warmth last December which was a mismatch to the La Niña background state. The more robust La Niña background states can feature strong gradient patterns in December with a cold Canada and Northern Tier. Especially when the pattern matches up so closely with the December MJO 6 composite. The forcing in the MJO 6 region is driving the U.S. Western ridge and colder Eastern trough pattern which will dominate December 1st through the 16th. The stronger blocking near Greenland is a result of the other area of the forcing in the Western Hemisphere and the recent +AAM spike in late November. So a bit of a hybrid composite with the split forcing. Split forcing pattern

Strengthening La Niña background state with the falling AAM heading into mid-December leading to the very amplified Aleutian Ridge and -PNA trough in Western Canada.

During the 1970s and 1980s NYC averaged around 6.2”more of snow than we have over the last 7 seasons and ISP 8.0” more. We didn’t have to rely exclusively on KU NESIS events back then like we do now to get over 20” of snow on the season. We used to get snowy clippers and SWFEs. Plus the colder climate allowed for heavier snows on the front end before mixing became an issue. We never experienced a climate before that was so challenging to get over 20” from EWR to NYC and ISP. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 0.0 0.9 2.3 3.7 6.4 1.6 T 14.9 2024-2025 0.0 0.0 2.8 3.0 7.1 0.0 0.0 12.9 2023-2024 0.0 T T 2.3 5.2 T 0.0 7.5 2022-2023 0.0 0.0 T T 2.2 0.1 0.0 2.3 2021-2022 0.0 T 0.2 15.3 2.0 0.4 0.0 17.9 2020-2021 0.0 0.0 10.5 2.1 26.0 T 0.0 38.6 2019-2020 0.0 0.0 2.5 2.3 T T T 4.8 2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5 Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean T 0.2 2.2 7.9 7.6 2.7 0.6 21.1 1988-1989 0.0 0.0 0.3 5.0 0.3 2.5 0.0 8.1 1987-1988 0.0 1.1 2.6 13.9 1.5 T 0.0 19.1 1986-1987 0.0 T 0.6 13.6 7.0 1.9 0.0 23.1 1985-1986 0.0 T 0.9 2.2 9.9 T T 13.0 1984-1985 0.0 T 5.5 8.4 10.0 0.2 T 24.1 1983-1984 0.0 T 1.6 11.7 0.2 11.9 0.0 25.4 1982-1983 0.0 0.0 3.0 1.9 21.5 T 0.8 27.2 1981-1982 0.0 0.0 2.1 11.8 0.4 0.7 9.6 24.6 1980-1981 0.0 T 2.8 8.0 T 8.6 0.0 19.4 1979-1980 T 0.0 3.5 2.0 2.7 4.6 T 12.8 1978-1979 0.0 2.2 0.5 6.6 20.1 T T 29.4 1977-1978 0.0 0.2 0.4 20.3 23.0 6.8 T 50.7 1976-1977 0.0 T 5.1 13.0 5.8 0.6 T 24.5 1975-1976 0.0 T 2.3 5.6 5.0 4.4 T 17.3 1974-1975 0.0 0.1 0.1 2.0 10.6 0.3 T 13.1 1973-1974 0.0 0.0 2.8 7.8 9.4 3.2 0.3 23.5 1972-1973 T T T 1.8 0.8 0.2 T 2.8 1971-1972 0.0 T T 2.8 17.8 2.3 T 22.9 1970-1971 0.0 0.0 2.4 11.4 T 1.3 0.4 15.5 1969-1970 0.0 T 6.8 8.4 6.4 4.0 T 25.6 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean T 0.6 2.1 6.0 7.1 1.0 T 16.8 2024-2025 0.0 0.0 2.1 2.7 6.9 0.0 0.0 11.7 2023-2024 0.0 T T 3.1 7.8 0.0 0.0 10.9 2022-2023 0.0 0.0 0.4 T 3.0 1.6 0.0 5.0 2021-2022 0.0 T 0.3 31.8 3.3 1.6 0.0 37.0 2020-2021 T 0.0 7.5 1.1 24.9 T T 33.5 2019-2020 0.0 0.1 4.2 2.5 0.0 T T 6.8 2018-2019 0.0 4.3 T 0.9 3.5 4.1 T 12.8 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean T 0.3 3.3 8.8 8.5 3.0 1.0 24.8 1988-1989 0.0 0.0 10.4 4.4 1.2 3.0 T 19.0 1987-1988 0.0 1.1 4.2 10.7 0.1 3.4 0.0 19.5 1986-1987 0.0 T 3.4 8.8 8.6 1.7 0.0 22.5 1985-1986 0.0 T 2.1 2.6 10.4 0.1 T 15.2 1984-1985 0.0 T 4.7 13.5 8.7 T T 26.9 1983-1984 0.0 T 2.6 11.9 T 13.0 0.0 27.5 1982-1983 0.0 0.0 3.2 1.5 26.1 T 1.1 31.9 1981-1982 0.0 0.0 1.0 18.1 0.3 T 16.0 35.4 1980-1981 0.0 T 0.5 13.2 T 7.1 0.0 20.8 1979-1980 T 0.0 1.5 4.0 1.5 2.0 0.0 9.0 1978-1979 0.0 4.0 T 6.9 17.2 T T 28.1 1977-1978 0.0 0.8 0.2 27.7 28.9 10.4 T 68.0 1976-1977 0.0 T 6.2 11.2 6.6 4.0 0.0 28.0 1975-1976 0.0 T 11.0 7.8 7.5 3.9 0.0 30.2 1974-1975 0.0 0.5 T 1.8 11.0 1.2 T 14.5 1973-1974 0.0 0.0 T 9.0 17.0 8.0 T 34.0 1972-1973 T 0.0 T 1.5 3.0 T T 4.5 1971-1972 0.0 T T 2.1 12.5 1.0 T 15.6 1970-1971 0.0 0.0 2.1 11.3 2.0 1.0 2.5 18.9 1969-1970 0.0 T 12.0 7.0 7.0 1.0 T 27.0

The fast Pacific flow and lack of blocking didn’t allow the cold high to stay anchored over New England. The WAR flexed just enough so the thermal gradient got pushed north of NYC. So these features negated the usual colder influence we see with lows tracking south of Long Island. Plus the low was strung out on a N-S axis without enough deepening near the benchmark to allow the cold air to wrap in behind the storm.

Yeah, we have seen a record expansion of the Aleutian ridge since 1980. Some years the axis is further west near the Aleutians. Other years the ridge is displaced further east over the NE PAC and or Canada.

I am glad that my early October indicator pointing to a more -PNA worked out again this year. Was expecting a decline in the PNA from the record levels last year. But we always have to wait until December in order to get the specific value. This is why Canada into the Northern Tier are so much colder than last December.

That smaller part is a representative subset of the wider Atlantic part of the Arctic which is also at record lows for the date. You can see record daily lows extending over to Svalbard on the Atlantic side of the Arctic. Due to geography and season, the September records have been more Pacific focused like in September 2012. So the record lows on the Atlantic side caused the entire Arctic to have a record low Jaxa extent on December 2nd. The extent is the lowest on record for the date at -425K below the previous record set in 2016. Winter records are usually more on the Atlantic side over the years since it’s easier to have open water extending into the Barents and Kara seas due to Atlantification of the Arctic. There is a much narrower opening to the Arctic near Alaska so it’s easier for the area north of Alaska to freeze over by this time of year. Wider Arctic low matches regional lows across the Arctic.

While we couldn’t make any progress with the persistent warm storm track pattern next few days, at least we are finally getting an Arctic outbreak focused right over the Northeast Friday morning.

Another case of the Arctic sea ice record lows occurring outside of the annual minimum period in September since 2012.

The split forcing that I mentioned is preventing s clean MJO 8 response due to the interference leading to a moderation of the pattern mid month on the EPS. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.pdf The MJO resumed its eastward propagation while greatly strengthening in amplitude over the Western Pacific during the past week. • RMM observations currently show the signal at greater than 3 standard deviations in amplitude, the highest registered since March, 2024 • Based on objectively wave filtered upper-level velocity potential anomalies, the recent strengthening is likely tied to higher frequency wave modes constructively interfering with both the enhanced and suppressed MJO envelopes. • The strong Western Pacific MJO has led to a weakening of the La Nina background circulation over the equatorial Pacific, with convective anomalies developing off the equator. • As the faster propagating tropical variability moves away of the slower MJO envelopes, a transition towards more competing interference is favored, resulting in a substantially weakened MJO signal over the Western Hemisphere during the next two weeks. • Even with a weakened MJO, subseasonal forcing still favors the greatest chances for tropical cyclone development over the South Pacific, with lowered chances over the Indian Ocean. • The extratropical response associated with Western Hemisphere MJO events during December historically consists of development of high latitude blocking over/near Greenland, potentially allowing for Arctic air to be advected into portions of the central and eastern CONUS.

The EPS has been handling this pattern pretty well over the last week or so. It has been fairly steady with the MJO 6 500 mb pattern dominating. Longer duration MJO 6 patterns tend to show a poleward shift with more ridging returning to Plains and East after the first 10 days. This matches the moderation the EPS has been showing in the pattern for mid month. So the first 10 days or so will probably be the coldest part of December relative to the means.

It’s climo for recent gradient patterns no matter what winter month it is. We warm up enough for mostly rain near the coast with amped systems. This was the case last February. But since February is colder we were able to get a little more snow on the front end before the changeover.

A new tropical oscillation called the TWISO has been recently discovered. So maybe the reason we are getting a strong MJO 6 gradient pattern in early December is somehow related to it being out of phase with the MJO. Plus the split forcing between the Maritime Continent and the Western Hemisphere could also be creating an interference pattern. Models showing a MJO 6 interference gradient pattern in early December https://www.pnas.org/doi/10.1073/pnas.2511549122 The tropical climate variability is characterized by various oscillations across a range of timescales. Oscillations that imprint the tropical mean state are generally attributed to slow processes, such as the seasonal cycle or interannual variability. Here, we identify a pronounced tropics-wide intraseasonal oscillation (TWISO) in satellite observations and reanalyses. This oscillation, with a period of 30 to 60 d, is evident across multiple variables and involves interactions between convection, radiation, surface fluxes, and large-scale circulation. It is primarily manifested as convective perturbations in the tropical Indo-Pacific warm pool accompanied by oscillations in the large-scale tropical overturning circulation. Here, we examine the relationship between TWISO, the Madden–Julian Oscillation (MJO), and the instability of radiative-convective equilibrium. Certain phases of TWISO coincide with specific phases of the MJO, suggesting a potential connection between the two. However, although the MJO can amplify the oscillation amplitude of TWISO, it is not essential for TWISO to occur. Finally, due to its broad manifestation across the tropics, TWISO potentially exerts widespread influence on tropical weather and climate at regional scales.

That being said, gradient patterns in recent years have been setting up just north of NYC. We haven’t been near a gradient pattern jackpot zone since February 2014 and 1994. The WAR amps just enough on the storm days and the highs move east of New England. This is what the current models runs are showing for early December.

I am hoping we can get follow up storm systems tracking south of Long Island in the coming weeks and months when it’s colder. We saw a storm take a similar track on 12-5-20 to our south with mostly rain along the coast. With very amped systems early in the season we need strong Arctic high pressure over New England like we got back on 11-15-18.

Big story this year continues to be the strong W to NW flow behind the lows racing by to our north. So far this year has had 63 days at Newark with wind gusts reaching 40 mph or higher. This resulted in the impressive sieche on Lake Erie

Looks like a split decision showing up for the first week of December. Long range models shifted colder with the trough into the East instead of the ridge from previous runs. But the large storm on the 2nd and 3rd shifted warmer with a further north track and stronger WAR. Main issue with the storm is the very fast flow and lack of blocking allowed the high over New England to move off the coast. So the further north storm and slightly stronger WAR on the day of the storm pushed the rain to snow gradient just to the north and west of NYC. Since the colder start to December is a new pattern not showing up until day 6-10, it’s uncertain how the current day 11-15 and beyond will actually play out. If you look back on our recent Decembers, they have a tendency to start out cold from the 1st through 15th. Then we get the warm up every year since 2011 between the 17th and 25th. So it will be interesting to see how things actually play out vs what the models are currently showing. We would want to eventually see a colder storm for our area while we still have the cold. This is very important during La Nina’s since we need to get over 6-7” of snow in December to match the above vs below seasonal snowfall that I outlined a few days back in this thread. So hopefully we can connect with at least one storm next few weeks while the colder start is still nearby. New early December pattern colder than old runs Old run too warm for early December New run warmer storm further north on the 2nd and 3rd Old run storm track colder to the south and more suppressed

Split forcing between the Maritime Continent and the Western Hemisphere appears to be causing an interference pattern resembling a phase 6 in early December. It could also be why the models have been showing so much volatility between runs over the last week as we head into December. A Northeast Pacific +TNH with a a cold upper low centered near Hudson Bay more closely resembles a phase 6 composite. So trying to guess what composite or pattern we end up with in mid to late December is anyone’s guess at this point. We will just have to let things play out next few weeks to see which area of forcing eventually wins out.

When we subtract the recent strongest El Niños from the era before the warming of the WPAC warm pool, it shows what I have been talking about. The WPAC hasn’t been cooling down like it used to during strong El Niños. So this leads to the forcing shifting further west than it previously did during El Niños. This is why we had Niña-like elements combining with the 2015-2016 and 2023-2024 events. During the weaker 2018-2019 and 2019-2020 events they couldn’t even couple and the La Niña background more completely dominated.

The 20th heaviest snowfall total through 11-26 at Marquette is very respectable. Time Series Summary for Marquette County Area, MI (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 2014-11-26 55.0 0 2 1989-11-26 49.3 0 3 1991-11-26 46.9 0 4 2000-11-26 46.8 0 5 2002-11-26 46.6 0 6 1997-11-26 44.9 0 7 2008-11-26 43.7 0 8 1988-11-26 43.3 0 9 1992-11-26 41.4 0 10 2018-11-26 40.8 0 11 2022-11-26 40.7 0 12 2005-11-26 39.8 0 13 1979-11-26 39.0 0 14 1993-11-26 38.7 0 15 1975-11-26 36.3 0 16 1976-11-26 31.1 0 17 2020-11-26 31.0 0 18 1995-11-26 29.8 0 19 1981-11-26 29.2 0 20 2025-11-26 28.9 0