bluewave

I don’t think it’s a coincidence that the rapid warming of the subtropical Pacific and Atlantic occurred with the super El Niño temperature jump in 15-16. This warming has been associated with the rapid expansion of the subtropical ridge near the East Coast of the U.S. and East of Japan to south of the Aleutians. This pattern has only become reinforced by the further record global temperature jump over the past 15 to 18 months. So this could be the result of a threshold effect related to the much warmer base state. It’s why the North Pacific pattern is so different from past -PDO instances. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078 The Pacific Decadal Oscillation (PDO) is a widely used measure of the temperature variability in the North Pacific Ocean. The PDO is the result of a well-known technique called empirical orthogonal function (EOF) analysis that isolates the most energetic modes of variability of the analyzed variable. The first time EOF analysis was applied to oceanographic data was in the 1970's when it was used to identify the most energetic modes of North Pacific sea surface temperature (SST). The first EOF of North Pacific SST has proved so useful as a measure that it received the moniker PDO. Our analysis suggests that a period of persistent marine heatwaves in the North Pacific since 2014 has been so powerful that this first mode of variability of SST has fundamentally changed and the PDO may not be as useful an indicator as it once was.

One of the sources for uncertainty is that several recent studies have found that the cool blob in the North Atlantic is associated with lower pressures and stronger winds rather than changes in the AMOC. In addition, it has recently been shown that the observed reduction in sea surface temperatures in the subpolar North Atlantic (also known as the warming hole), often assumed to be an indication of the AMOC slowdown, could largely be driven by the atmosphere alone without any changes in ocean circulation2

Nearly all of the winter Aleutian Ridge 500mb anomaly since 1999 is a result of 16-17 to 23-24.

The one early snowfall indicator which has worked for every La Niña winter in NYC going back to the 95-96 has been the December La Niña snowfall. Years with 3 or more inches December have gone on to above normal seasonal snowfall. Every December with under 3” has had a below average snowfall season. This is why December is so important with La Ninas around NYC. 22-23….Dec snow…..T……season….2.3 21-22…..Dec snow….0.2…season…..17.9 20-21…..Dec snow….10.5…season…38.6 17-18……Dec snow….7.7…..season…40.9 16-17…….Dec snow…3.2…..season…30.2 11-12…….Dec snow….0…….season….7.4 10-11…….Dec snow….20.1….season….61.9 08-09…..Dec snow….6.0……season….27.6 07-08…..Dec snow…..2.9…..season….11.9 05-06…..Dec snow…..9.7…….season…40.0 00-01……Dec snow….13.4……season….35.0 99-00…..Dec snow…..T……….season….16.3 98-99…..Dec snow…..2.0……..season….12.7 95-96…..Dec snow…..11.5……..season….75.6

That was before the Pacific became so hostile.

That’s the strongest the Aleutian Ridge out near the Dateline has been from January into October. 2020 5631.444 2021 5647.413 2022 5622.112 2023 5646.048 2024 5655.698

SMQ already set the record by a good margin at 121 days reaching 80° since they didn’t have the sea breeze to deal with this summer. Time Series Summary for SOMERSET AIRPORT, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2024 121 58 2 2016 117 0 3 2007 111 0 4 2005 109 1 5 2020 105 0

EWR needs two more 80° days to tie the record of 118 days set back in 2015. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2015 118 0 2 2024 116 58 - 2021 116 0 3 1994 114 0 4 2016 113 0 - 1993 113 0 - 1991 113 0 5 2011 111 0 - 2010 111 0

Since the CAA has been so weak this fall NYC is on track for one of their latest first under 40° readings. First/Last Summary for NY CITY CENTRAL PARK, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 1938 04-11 (1938) 33 11-15 (1938) 37 217 2022 04-19 (2022) 39 11-14 (2022) 37 208 1946 04-28 (1946) 37 11-13 (1946) 38 198 1977 05-09 (1977) 36 11-12 (1977) 37 186 1916 04-10 (1916) 38 11-12 (1916) 38 215 1994 04-08 (1994) 34 11-11 (1994) 38 216 1898 04-29 (1898) 39 11-11 (1898) 38 195 1961 04-20 (1961) 38 11-09 (1961) 35 202 1943 04-22 (1943) 39 11-09 (1943) 38 200 2019 04-06 (2019) 39 11-08 (2019) 29 215 2017 04-01 (2017) 37 11-08 (2017) 39 220 1955 04-09 (1955) 39 11-08 (1955) 38 212 1971 04-25 (1971) 38 11-07 (1971) 34 195 1973 04-15 (1973) 39 11-06 (1973) 34 204 1931 04-30 (1931) 38 11-06 (1931) 34 189 1927 04-25 (1927) 38 11-06 (1927) 34 194 1918 04-25 (1918) 39 11-06 (1918) 38 194 1953 04-21 (1953) 36 11-05 (1953) 35 197

You had to be away from the water north of the LIE to get the freeze since spots like the Stony Brook mesonet missed it.

The signal is so strong for warmth that all the guidance sees it pretty well.

Places like ISP missed their first freeze getting down to 34°. So they have a shot at one of the latest first freezes on record since there won’t be much cold around next few weeks. The latest on record occurred on 11-15-22. Frost/Freeze Summary for ISLIP-LI MACARTHUR AP, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 2022 03-30 (2022) 25 11-15 (2022) 29 229 1984 04-10 (1984) 30 11-15 (1984) 29 218 2016 04-10 (2016) 32 11-14 (2016) 32 217 1994 04-23 (1994) 32 11-12 (1994) 32 202 1981 04-22 (1981) 32 11-12 (1981) 31 203 1977 04-11 (1977) 32 11-12 (1977) 32 214 2005 04-17 (2005) 30 11-11 (2005) 30 207 2017 03-30 (2017) 32 11-10 (2017) 26 224

2024 is currently in the lead in your area just ahead of 2012 through November 3rd. Time Series Summary for Buffalo Area, NY (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 2024-11-03 55.7 0 2 2012-11-03 54.9 0 3 2021-11-03 54.5 0 4 1921-11-03 53.9 0 5 2016-11-03 53.8 0 6 2020-11-03 53.7 0 - 1991-11-03 53.7 0 7 2023-11-03 53.5 0 - 2017-11-03 53.5 0 8 1949-11-03 53.4 0 9 1998-11-03 53.3 0 10 1955-11-03 53.1 0

It’s a key component of the AMOC as outlined in the recent paper. https://www.aoml.noaa.gov/reassessing-the-stability-of-the-florida-current-new-insights-from-40-years-of-observations/ However, the strength of the Florida Current, a key component of the AMOC, has remained stable for the past four decades, according to a new study by scientists at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML), the University of Miami Cooperative Institute for Marine and Atmospheric Studies (CIMAS) and Rosenstiel School, and the National Oceanography Centre (UK).

The last 9 year winter average temperature rise has been impressive at all our local sites. NYC has seen the same rate of increase as ISP vs the 81-10 means. HPN has experienced a slightly higher increase. NYC….81-10…35.1°……last 9 winters….38.5°…+3.4° ISP……81-10…33.0°…..last 9 winters….36.4°….+3.4° HPN….81-10…30.9°….last 9 winters….34.8°…..+3.9°

The 81-10 winter normals at ISP were 33.0° vs 35.3° at IAD.

The ISP winter average temperature since 15-16 has been 36.4°. The 81-10 climate normals at IAD in the Washington DC suburbs were 35.3°. So ISP has been about a degree warmer than the 81-10 winter means in Suburban Northern VA.

Our only 2 months without 80s have been December and January. But since the 2nd half of December has been warming faster than 1st half, the 12-7-98 Newark monthly max of 76° has been unbeatable so far. Getting to 80° in January would still be a stretch since the currently monthly max is still 74° at Newark in 1950. But under the right set of conditions, 75 to 78° could be in range one of these years.

Our big winter event since 15-16 around NYC has been an historic run of 9 warmer to record warm winters in a row. The 38.5° 9 winter average for NYC was a little warmer than the DCA 81-10 average of 38.2°. So we have had a mid-Atlantic winter temperature regime.

The one constant with the CanSIPS recent winter forecasts has been that the actual area where the ridge axis set up was much warmer than those 2m temperature forecasts. The same goes for most of the other seasonal guidance. It could be that once a standing wave gets going that it’s very hard for the models beyond the medium range to keep pace with the actual temperature departures.

Newark has a shot at 80° on Wednesday as the highs have been beating guidance with the drought recently. This would only be the 4th time Newark made it over 80° after November 5th. The most recent occurrence was back in 2022. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 2022-12-31 81 0 2 1993-12-31 80 0 - 1948-12-31 80 0

The main hope is that a piece of the wetter pattern to our west comes east mid to late month. But it will have to show up under 120hrs to be believable. Otherwise it’s just another version of the GFS 384 hr snowstorm that keeps getting pushed back.

The change since 15-16 was more of a shift rather than linear. The future will depend on the choices the global society makes. So that aspect is unpredictable. But a business as usual pattern for another 30 years will make the last decade seem cold by comparison. The cost of business as usual may become so great that process forces a change and the climate reaches a point of stabilization rather than these rapid jumps associated with non linear changes.

The winter average temperature since December 15 has been the same temperature as Virginia just south of DC had from 81-10. NYC has been at 38.5° last 9 winters and the old 81-10 DCA normals were 38.2°.So we have mid-Atlantic climate now. If the warming goes unchecked next 30 years, then we may get the 81-10 Norfolk or interior NC old normals. Historic pattern of winter warmth since the +13.3 December 2015 continues. This makes it a first 9 warmer to record warm winters in a row. It included 21 out of the last 27 winter months finishing warmer than average. NYC Feb 24…+4.2 Jan 24..+3.3 Dec 23..+5.5 …………..+4.3 Feb 23…+5.2 Jan 23…+9.8 Dec 22…-0.6 …………..+4.8 Feb 22….+1.4 Jan 22….-3.2 Dec 21….+4.7 ……………..+1.0 Feb 21….-1.7 Jan 21….+1.1 Dec 20…+1.7 …………..+0.4 Feb 20…+4.8 Jan 20….+6.5 Dec 19….+0.8 …………….+4.0 Feb 19….+0.9 Jan 19….-0.1 Dec 18…+2.6 …………….+1.1 Feb 18…+6.7 Jan 18….-0.9 Dec 17…..-2.5 …………….+1.1 Feb 17…..+6.3 Jan 17….+5.4 Dec 16….+0.8 …………….+4.2 Feb 16….+2.4 Jan 16….+1.9 Dec 15….+13.3 …………….+5.9

NYC was one of the cool outliers as all the other local stations were top 10 warmest for October. Many stations finished near the top for average maximum temperatures. So the lower ranking for NYC was artificial due to the excessive tree growth keeping the maximums much lower than all the other stations relative to the maximums. The tree growth issue was even more amplified since this was one of the most lopsided months for the maximums driving the departures. Time Series Summary for WESTCHESTER CO AP, NY - Month of Oct Click column heading to sort ascending, click again to sort descending. 1 2017 61.5 0 2 1971 60.3 0 3 2007 60.1 0 4 2021 59.8 3 5 1963 58.5 0 6 1954 58.0 0 7 2023 57.9 0 - 1995 57.9 10 8 1984 57.8 0 9 2024 57.5 0 - 1949 57.5 0 10 1990 57.3 2 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Oct Click column heading to sort ascending, click again to sort descending. 1 2021 64.4 0 2 2017 63.8 0 3 2007 63.5 0 4 1971 63.1 0 5 1990 62.4 0 6 1984 62.2 0 7 2023 62.0 0 8 1949 61.6 0 9 2024 61.5 0 10 1963 61.2 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Oct Click column heading to sort ascending, click again to sort descending. 1 1971 63.5 0 2 2017 63.2 0 3 2021 63.0 0 - 2007 63.0 0 5 1984 61.7 0 6 1995 61.6 0 7 1990 61.3 0 8 2024 61.1 0 - 1949 61.1 0 9 1954 60.1 0 10 2013 60.0 0 Go Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Oct Click column heading to sort ascending, click again to sort descending. 1 2017 61.9 0 2 2021 61.2 0 3 2007 61.1 0 4 1990 60.9 0 5 1971 59.7 0 6 2023 58.8 0 7 1995 58.5 0 8 2024 58.4 0 9 1963 58.3 0 10 2019 57.9 0 - 2013 57.9 0 - 2012 57.9 0 Go Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Oct Click column heading to sort ascending, click again to sort descending. 1 2017 61.9 0 2 2021 61.2 0 3 2007 61.1 0 4 1990 60.9 0 5 1971 59.7 0 6 2023 58.8 0 7 1995 58.5 0 8 2024 58.4 0 9 1963 58.3 0 10 2019 57.9 0 - 2013 57.9 0 - 2012 57.9