bluewave

It’s little details like that which can be challenging detect much before we get to within the range of the 6-10 and 11-15 day forecast. The winter began with the near record Aleutian Ridge -PNA and very amplified MJO 6-7 forcing in December leading to the +13 warmest December at DFW. But we got the great MJO 8 in January salvaging the entire winter. Even though areas south of New England flipped back to the warmer and less snowy pattern in February. Unfortunately, we have had more examples of big MJO 4-7 transits weakening before 8 only to reload in 4-7 again. So we will probably need some help from the MJO 8 or even something else in order to avoid the winter pattern which has been locked in since February 2022.

The MJO forecasts look like we are following the warmer and less snowy groupings of La Ninas since 2010 in October 2011, 2016, 2021, and 2022 staying under +2. The better La Nina’s were higher than +2.8 like we got in 2010, 2017, and 2020. I will update the exact RMM number we reach in a few weeks. My guess is that these weaker MJO 4-6 Octobers were able to rebound stronger from December into January allowing the MJO 4-6 to have a strong influence on the pattern. The stronger MJO 4-6s in October were more muted in December allowing the other phases and factors to dominate. But even though 17-18 started out great through early January getting into phase 8, we did end up with record 4-6 activity from mid-January into February. So it was one case where the strong October MJO 4-6 reemerged mid to late winter. While 16-17 was a warmer La Niña winter, the MJO 4-6 activity wasn’t too outrageous. But the warmth was driven by the very amplified Aleutian Ridge which acted like a strong MJO 4-6 even though the RMM wasn’t as strong as say 2011-2012, 2021-2022, and 2023. In general the MJO 4-7 phases have been very amplified regardless of ENSO state since December 2015. We could even point to March 2012 as a bit of a precursor as to what would happen to the MJO several years later. It’s based on the MJO RMM amplitude and VP anomalies in phase 5-6 during La Niña Octobers since 2010. The stronger October MJO responses had better winters in NYC relative to the other La Ninas in the multiyear event group. Those stronger MJO 5-6 Octobers also had the more robust peak La Niña ONIs from fall into winter of the multiyear groups. All the La Niña winters around NYC since 11-12 have averaged warmer than normal. But even the warmer than average 17-18 and 20-21 winters had better snowfall than the other years in the multiyear group. In addition, we haven’t had any cold neutral ENSOs in the -0.1 to -0.5 peak range with a strong -PDO since 2010. So not sure how the relationship would work for any year with the official CPC ONI not getting colder than -0.5. The other thing to consider is that we don’t know how long this relationship will continue to work it. So I will update this post with some early ideas for the coming winter after we see how the MJO verifies for the month of October. http://www.bom.gov.au/clim_data/IDCKGEM000/rmm.74toRealtime.txt https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php Multiyear La Niña groupings below with peak MJO 5-6 strength and the peak ONI from the fall into winter…….Strongest October MJO 5-6 and La Niña ONI leading to best NYC winters of the multiyear group bolded… October 2022…Phase 6 peak +2.177…..ONI….-1.0 October 2021….Phase 5 peak +2.087….ONI….-1.0 October 2020…Phase 5 peak +2.818….ONI…..-1.3 October 2017….Phase 6 peak +3.353….ONI….-1.0 October 2016….Phase 5 peak +1.800….ONI….-0.7 October 2011….Phase 6 peak +1.674….ONI….-1.1 October 2010….Phase 5 peak +2.880…ONI…..-1.6

Pretty much the October version of our recent highly amplified Aleutian Ridge and Southeast Ridge decadal winter pattern

The PDO at 500 mb is also near the most negative on record for the first half of October matching the SST index. This is a continuation of the record Aleutian ridge which has been in place this year. The poleward extension over the next 10 days will help to amplify the Southeast Ridge to near record levels for late October as the AO sees a near record increase also.

We were fortunate with parts of the area coming off the wettest July 2023 to August 2024 with over 100” in spots before the dry pattern began in late August. So while the drought monitor has been increasing the top layer and vegetation dryness in recent updates, the groundwater and surface reservoir supply is still in very good condition. It was probably the first time in U.S. history that a location like Suffolk County had a 12.00+ rainfall event in late August followed by such a 50 day dry stretch. Not sure any other parts of the U.S. experienced a short term deluge like that with so little rainfall in the following months.

I don’t think it was a coincidence that 2018 was the last top 10 coldest fall in Canada and Rockford, IL broke their all-time coldest temperature at -31 in late January. Granted the record cold that month was shorter lived and of a smaller aerial coverage than past Midwest Arctic outbreaks from the 1980s, but the cold in Canada during the fall gives us some hints ahead of time.It’s been a similar pattern for the Northeast with the strongest Arctic outbreaks over the last decade going to our west with the stronger WAR Southeast Ridge. https://www.canada.ca/content/dam/eccc/documents/csv/climate-trends-variations/autumn2023/Autumn_2023_regional_temp_table_e.csv https://www.weather.gov/lot/RecordColdJan2019

Yeah, the GFS came in over 591 DM with the ridge this weekend.

Yeah, Canada hasn’t had a colder than average winter since 2014 by their 1961-1990 reference period. Their last top 10 coldest winter was back in 1994 when we had all the record cold in the East and very impressive snowfall. But in general the warmest winters are El Niño. They set the record by a wide margin last winter. The 20-21 winter was their 5 warmest overall and 16-17 was 8th warmest. So some recent La Ninas have also been very warm by Canadian standards. https://www.canada.ca/content/dam/eccc/documents/csv/climate-trends-variations/winter2024/Winter_2024_regional_temp_table_e.csv https://www.canada.ca/en/environment-climate-change/services/climate-change/science-research-data/climate-trends-variability/trends-variations/winter-2024-bulletin.html

The Aleutian Ridge has been so strong from east of Japan to the Dateline that the Pacific Jet got forced much further north than usual leaving much of the CONUS dry.

AO volatility continues with one of the strongest October AO near 5 SD reversals following the recent very strong forcing near India.

It will initially start out as an over the top warm up with the near record 590 dm ridge for late October. But it takes several days for the warmest temps to make into the region like we saw over the summer. It’s late October so we will be getting highs of 75-80°. When we had a near record 500mb ridge back over the summer it was 95°-100°. We got lucky that this dry pattern since August 20th is well past the peak summer heating.

These big ridges over the Northeast have become the new normal as the GFS and Euro are both at least 590 dm.

It makes perfect sense if you understand that the ranking is done by the temperature and not the year. So multiple years can share the same temperature. It makes no sense to leave a gap in the ranks just because a tie occurs. Ties in scores are handled by giving the tied rows the same rank, and the next rank is then incremented without any gaps.

Stronger winds today than model forecasts since the high temps beating guidance again resulted in steeper low level lapse rates.

It’s a more accurate way of keeping statistical rankings when the distribution becomes more skewed to either the top or bottom of the range. The old way came about when we were in a stable climate era and month after month wasn’t in the top 10 warmest. So ranks aren’t skipped since there can be numerous ties near the top 10 in a rapidly warming climate. Creating gaps due to numerous ties artificially pushes similar temperatures out of the top 10. The NWS out in Upton has been doing it this way also. DENSE_RANK () does not leave gapsin the rank sequence when there are ties in the ordering. It ensures that rows with the same values in the ORDER BY clause receive the same rank, and the next rank is then incremented without any gaps

If this dry pattern continues through November, then it would be the first time that Long Island had a driest season since 2001-2002. The driest seasons at ISP were the fall of 1965, winter 2001-2002, spring 1995, and summer 1966. Even if ISP can increase the rainfall enough in November, it could still finish close to 2001 which was the 2nd driest fall on record. 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 0.34 48 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 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. 1 2001-2002 5.38 0 2 1979-1980 5.51 0 3 1984-1985 5.67 0 4 1976-1977 6.04 0 5 1966-1967 6.58 0 6 2011-2012 6.86 0 - 1980-1981 6.86 0 7 1985-1986 7.47 0 8 1963-1964 7.94 2 9 2003-2004 8.04 0 10 1999-2000 8.05 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Mar through May Click column heading to sort ascending, click again to sort descending. 1 1995 6.00 0 2 1965 6.08 2 3 1986 6.49 0 4 1976 6.85 0 5 1981 6.95 0 6 2015 7.15 0 7 2013 7.22 0 8 1969 8.24 0 9 1985 8.30 0 10 1992 8.45 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Jun through Aug Click column heading to sort ascending, click again to sort descending. 1 1966 3.67 0 2 2005 3.74 0 3 1988 4.52 0 4 2022 4.75 0 5 1993 4.91 0 6 1964 5.10 0 7 2016 5.25 0 8 1974 6.13 0 9 1995 6.76 0 10 2015 7.27 0

Going to be tough to get much rain here with the models advertising a near record 590 dm ridge for next weekend.

While we still have big rainfall surplus since July 2023, several stations have had their driest start to fall. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 2024-10-12 0.89 0 2 1941-10-12 1.24 0 3 1931-10-12 1.58 0 4 1953-10-12 1.78 0 5 2013-10-12 1.92 0 - 1970-10-12 1.92 0 Time Series Summary for WESTCHESTER CO AP, NY Click column heading to sort ascending, click again to sort descending. 1 2024-10-12 0.83 0 2 2009-10-12 1.32 0 3 1986-10-12 1.73 0 4 1964-10-12 1.85 0 5 1970-10-12 1.90 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. 1 2024-10-12 0.34 0 2 1982-10-12 1.28 0 3 2019-10-12 1.38 0 4 1997-10-12 1.42 0 5 1986-10-12 1.63 0

No. I used dense rank sorting by temperature. https://medium.com/@kumarsatwik25/rank-and-dense-rank-in-sql-23ffcf77611e DENSE RANK (): The DENSE_RANK () function is a window function in SQL that assigns a unique rank to each distinct row within a result set, based on a specified ordering. Unlike the RANK () function, DENSE_RANK () does not leave gapsin the rank sequence when there are ties in the ordering. It ensures that rows with the same values in the ORDER BY clause receive the same rank, and the next rank is then incremented without any gaps.

The record warmth in Canada seems like a lingering El Niño influence combined with record Pacific WPAC warm pool going back to 2023.

Cooler week 1 followed by warmer week 2 with the dry pattern continuing. October 14-21 Oct 21-28

These new 1991-2020 climate normals as so warm that a small +1.4 summer in Boston was still the 9th warmest average temperature at 73°. While I know farming and energy customers need these regular climate normals updates, they tend to minimize the warming which has occurred. The next time we see a cooler winter in the Northeast, it could be a result of the new much warmer winter climate normals. But would have been considered a warmer winter in our older climate era. Time Series Summary for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 2021 74.6 0 2 1983 74.1 0 - 1949 74.1 0 3 2022 74.0 0 4 1994 73.9 0 5 2019 73.7 0 - 2018 73.7 0 6 2016 73.6 0 - 2010 73.6 0 7 1952 73.4 0 8 1984 73.3 0 9 2024 73.0 0 - 1973 73.0 0 10 2020 72.9 0 - 2013 72.9 0

A rare October 40° temperature gradient today with 80° in NJ and closer to 40° in NY State.

The 38.5° NYC average over the last 9 years was a little warmer than the DCA 1981-2010 winter average of 38.2°. https://ggweather.com/normals/DC81.html

I believe this may be the first time in U.S. history that a part of the county experienced 9 consecutive warmer than average winters with numerous all-time winter warmth records being set. 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