bluewave

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

It’s gone way beyond the -PDO. That’s why we never saw this type of sustained warmth for 9 straight winters before. This recent paper discusses the historic rise in the SSTs from east of Japan to south of the Aleutians. Plus the subtropical Atlantic has warmed far beyond any past +AMO periods. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078 The fundamental result of this study is that the first EOF of SST in the North Pacific has changed starting in 2014. For more than 20 years, the PDO has been used to describe the state of the North Pacific. However, since the marine heatwave of 2014, there have been remarkable changes to the dominant mode of SST in the North Pacific. The spatial pattern of the first EOF of SST from 1950 to 2021 is notably different from the PDO, suggesting that though the PDO served as a useful metric of SST variations until 2014 (Johnstone & Mantua, 2014), it may no longer be as effective a climate index for the North Pacific. From 1950 until the 2014 MHW, the first EOF remained consistent in its proportion of positive and negative regions with both taking up roughly half the area of the North Pacific (and with the positive region taken to be the eastern Pacific). When EOFs are calculated from 1950 to endpoints after 2014, the first EOF has a maximum positive region covering 77% of the North Pacific, with a PC indicating the largest anomalies on record. These changes to the first EOF/PC of North Pacific SST are nothing short of remarkable. In concert with these changes, the second EOF/PC of SST has also undergone profound evolution since 2014. This second EOF now accounts for approximately 18% of the variability, growing from 13% during the 1950–2013 period. The spatial structure of the second EOF now is positive over almost the entire basin, with a PC that has grown strongly positive in the last several years. Thus, the second EOF/PC describes warming over much of the Pacific not in the positive lobe of the first EOF.

Numerous local stations set a new monthly maximum temperature for the entire month of November or tied the old max yesterday. This is our first new monthly max since the mid 90s in October 2019. Luckily this wasn’t during July since there would have been widespread 100s. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. 1 2024 82 29 2 2022 80 0 - 1950 80 1 3 1993 77 0 - 1982 77 0 - 1975 77 0 Time Series Summary for WESTCHESTER CO AP, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. 1 2024 79 29 2 2003 78 0 - 1974 78 0 3 1993 77 1 Time Series Summary for IGOR I SIKORSKY MEMORIAL AIRPORT, CT - Month of Nov Click column heading to sort ascending, click again to sort descending. 1 2024 81 29 2 2022 79 0 3 1993 78 0 - 1975 78 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. 1 2024 80 29 - 2022 80 0 3 1990 78 0 Time Series Summary for New Brunswick Area, NJ (ThreadEx) - Month of Nov Click column heading to sort ascending, click again to sort descending. 1 2024 83 29 2 2003 82 0 - 1950 82 0 3 2020 80 0 - 1982 80 0 - 1974 80 0 - 1948 80 0 Time Series Summary for SUSSEX AIRPORT, NJ - Month of Nov Click column heading to sort ascending, click again to sort descending. 1 2024 79 29 2 2003 78 0 3 2020 77 0 4 2022 76 2 - 2015 76 0 - 2001 76 1

The monthly max departures dominated over the mins due to the record high pressure, drought, and good radiational cooling conditions.

If a 20-40 meter Southeast Ridge 500 mb anomaly actually verified like the CanSIPS is showing , then the temperature anomalies would be much warmer. The 500 millibar anomaly chart is close to the 16-17 La Niña winter. Several locations that winter went 5+. We would need at least one month with a big mismatch pattern for the La Niña and -PDO to stay in the more moderate +1 to + 3 range where the warmest departures actually set up.

First time that Newark had 5 days reaching 80° or warmer after October 20th. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 2024-12-31 5 61 2 1979-12-31 3 0 - 1950-12-31 3 0 - 1947-12-31 3 0 3 2023-12-31 2 0 - 1963-12-31 2 0 - 1946-12-31 2 0

The early unofficial ranking for October was 3rd warmest for the CONUS based on Prism temperatures. The official rankings should be out in a few weeks. 2016 is currently ranked 3rd and 2015 was 5th warmest. Our last top 10 coldest October was in 2009 which finished at 4th coldest. Several mid-Atlantic stations had their snowiest season on record following that cold October. It was the last one that several Southeast locations registered a top 10 coldest winter.

Yeah, this +EPO pattern has been on steroids. We have about 5 weeks to see if a wetter pattern can emerge by early December. Nobody wants to see a repeat of the 01-02 dry pattern which ran from the fall of 01 into the summer of 02.

We are going to need a big reversal of this dry pattern mid to late month in order to avoid the driest fall since 2001. Time Series Summary for Philadelphia Area, PA (ThreadEx) - Sep through Nov Click column heading to sort ascending, click again to sort descending. 1 2024 0.77 30 2 1922 2.37 0 3 1879 2.91 0 4 1915 3.66 0 5 2001 3.97 0 6 1884 4.05 0 7 1871 4.09 61 8 1914 4.14 0 9 1908 4.27 0 10 1990 4.56 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Sep through Nov Click column heading to sort ascending, click again to sort descending. 1 2024 0.36 30 2 1965 3.31 0 3 2001 4.02 0 4 2013 4.86 0 5 1973 5.38 0 6 1998 5.96 0 7 1982 6.34 0 8 2007 6.50 0 9 1967 6.56 0 10 1994 7.42 0

More record warmth to start November with highs approaching 80° again right onto Long Island. Very strong downslope offshore flow. The steeper low level lapse rates with the dry frontal passage will allow wind gusts to approach 35-40 mph.

Some spots to our north approached +30 today. THE WATERTOWN NY CLIMATE SUMMARY FOR OCTOBER 31 2024... VALID TODAY AS OF 0400 PM LOCAL TIME. CLIMATE NORMAL PERIOD: 1991 TO 2020 CLIMATE RECORD PERIOD: 1949 TO 2024 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST VALUE (LST) VALUE VALUE FROM YEAR NORMAL ................................................................... TEMPERATURE (F) TODAY MAXIMUM 78R 2:30 PM 72 1989 53 25 42 MINIMUM 63 6:25 AM 15 2002 35 28 26 AVERAGE 71 44 27 34

Looks like the warmest October on record north of 80N. https://ocean.dmi.dk/arctic/meant80n.uk.php

Latest 80°reading of the year at HPN beating 2023 and 1989 by 2-3 days. https://www.weather.gov/wrh/timeseries?site=khpn First/Last Summary for WESTCHESTER CO 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. 1989 03-28 (1989) 80 10-29 (1989) 82 214 2023 04-12 (2023) 82 10-28 (2023) 81 198 1963 05-05 (1963) 83 10-28 (1963) 80 175 1979 05-09 (1979) 86 10-22 (1979) 82 165 2016 05-25 (2016) 87 10-19 (2016) 83 146

Only the 4th time that JFK will finish October with a 70° or warmer average high temperature. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Oct Click column heading to sort ascending, click again to sort descending warmest average high temperature 1 2017 71.0 0 2 2024 70.2 1 - 1971 70.2 0 3 2007 70.1 0 4 2021 69.9 0 5 1963 69.2 0 6 1995 69.0 0 7 1949 68.7 0 8 1984 68.6 0 9 1990 68.4 0 10 1961 68.3 0

The record 500 mb block which was over Canada since May 2023 finally came south.

The coast to coast blocking ridge shut the rainfall off for a large portion of the U.S.

Even areas north of LIE on LI could see 80° before the sea breeze arrives later today.