bluewave

Lander, Wyoming hit the snowfall jackpot this month.

My guess is that record +30C warm pool is slowing the forcing down around the Maritime Continent instead of allowing it to move more quickly to the east. New run forcing further west Old run was further east

This is the first time at the start of December that such a strong El Niño had an extensive +30C SST pool from the Maritime Continent to east of the Dateline.

Yeah, we need these day 11-15 favorable Pacific forecast patterns to still be there once we are in the more reliable day 6-10 forecast period. We can remember how the day 11-15 EPS had a favorable Pacific pattern to start December. Now the new day 6-10 is milder than the old day 11-15 since a trough is forecast to dig into the West. New run for December 1st Old run for December 1st

The early February 21 blizzard worked since the upper low lingered in place near the East Coast after the December into January 20-21 +PNA. Plus we got a great Rockies ridge amplification at the time of the storm which was an effective +PNA even if the raw indices had a -PNA. That’s why I am a big fan of using 500 mb anomalies over the raw indices at times. So even though we were technically -PNA at storm time, it was nothing like the raging -PNA we had last winter with the trough digging into the Baja.

I believe the last time a favorable EPS 11-15 forecast this time of year verified in our favor was in 2020.

You were talking about a wintery precip threat a while back for late November. I pointed out to you that we seldom see this with a piece of the trough hanging back to the SW . Any amplified short waves will pump the SE ridge which is what is happening with this storm system. So we only need a SE ridge for 1 day to result in a warmer storm track.

Same old story of recent years with a stronger SE ridge than forecast resulting in a further west storm track. New run Old run

Yet we have some very strong forcing in the MJO 2 to 4 regions along with the Nino itself near the Dateline. It’s why the RMM charts aren’t of much use right now. This is like the atmosphere playing a chord instead of individual Nino or Niña notes. So plenty of competing influences to go around with dueling +30 C warm pools in the WPAC and around the Dateline.

Cruising toward at least our first week at super El Niño levels. Very warm in Nino 3 also. Plus it looks like Nino 4 is approaching the all-time weekly record of +1.7 set in 15-16. https://www.cpc.ncep.noaa.gov/data/indices/wksst9120.for

It will be colder than the lowest November maxes last few years. But the 2019 and 2018 low maxes for the month of November at 34 and 28 should be safe. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. Year Lowest Max Temperature Missing Count 2023 44 6 2022 40 0 2021 39 0 2020 36 0 2019 34 0 2018 28 0 2017 38 0 2016 41 0 2015 44 0 2014 36 0 2013 30 0 2012 40 0 2011 46 0 2010 42 0

The surface temperature departures this month have been less impressive than the departures at 850 mb over the Northeast. So while this will probably be our coldest temperatures of the fall so far, probably nothing too out of the ordinary for this time of year.

Yeah, it just makes the last 5 years seem even lower then they were. So we went from the highest 5 year snowfall total to the 7th lowest. These all of nothing snowfall patterns have become the new normal after the record 95-96 season was followed by 8 lowest 5 year snowfall total. Minimum 5-Year Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Value Ending Date Missing Days Period of record: 1871-01-01 to 2023-11-24 1 66.1 1932-12-31 0 2 66.2 1931-12-31 0 3 71.9 1955-12-31 0 4 72.2 1954-12-31 0 5 74.8 1992-12-31 0 6 77.0 1953-12-31 0 7 77.7 2023-12-31 37 8 79.4 2001-12-31 1 9 81.8 1977-12-31 0 - 77.7 1975-12-31 0

2014 to 2018 is going to be tough to beat for 5 year maximum snowfall since it was probably at least a 100 year event. Maximum 5-Year Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Value Dates Missing Days 1 269.9 2014-01-01 through 2018-12-31 0 2 256.2 2013-01-01 through 2017-12-31 0 3 227.0 2015-01-01 through 2019-12-31 0 4 223.3 2012-01-01 through 2016-12-31 0 5 219.4 2011-01-01 through 2015-12-31 0 Maximum 5-Year Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Value Dates Missing Days 1 209.4 2014-01-01 through 2018-12-31 0 2 205.2 1914-01-01 through 1918-12-31 2 3 204.9 1892-01-01 through 1896-12-31 3 4 204.3 1893-01-01 through 1897-12-31 3 5 202.1 1944-01-01 through 1948-12-31 0

A record breaking 8 warmer than normal winters in a row since the 15-16 super El Niño. Then we have the December warming trend which has the 2nd half of the month warming faster than the first half. This has lead to to regular 55°+ highs around the solstice from December 17th to 25th every year since 2011. The average December 1-15th high in NYC back in 1981 was around 39.6° and only warmed to 41.0° in 2022 for a rise of +1.4. The December 16-31 average temperature rose much more steeply from 35.2° to 39.0° for a large increase of +3.8°. So the late December average temperature in the 2020s is nearly the same as the early December temperature in the early 1980s. Snowfall has been much more variable and has been in all or nothing mode. Great outcomes from 15-16 to 17-18. Then a significant drop from 18-19 to 22-23. But we did have the great 20-21 season across the region and the January 22 record snows on Long Island. Forecasts for snow need to make it into the 120 hr or lower forecast period to be believable since we have had so many day 6-10 and 11-15 patterns which looked snowy that never verified. NYC 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 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Highest Max Temperature Dec 17 to Dec 25 Missing Count 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 2010-12-25 40 0 2009-12-25 39 0

The warmest temperatures of the whole season came in September this year. Plus we had record heat in late October. Since the 1991-2020 climate normals have warmed so much, we can still have a top 20 warmest summer with only a +0.3 departure at Islip. Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season 2023 93 90 91 96 91 97 85 97 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Year Mean Avg Temperature Missing Count 1 2010 74.7 0 2 2022 74.6 0 - 2020 74.6 0 3 1999 74.5 0 4 2016 74.4 0 5 2011 73.9 0 6 2019 73.8 0 7 2021 73.7 0 8 2018 73.5 0 - 2005 73.5 0 9 2013 73.4 0 10 2012 73.3 0 - 1991 73.3 0 11 2015 73.2 0 - 1980 73.2 0 12 1994 73.0 0 - 1966 73.0 0 13 2008 72.9 0 - 1995 72.9 0 14 2006 72.8 0 - 1998 72.8 0 15 2002 72.7 0 - 1973 72.7 0 16 2023 72.6 0 - 1993 72.6 0 - 1988 72.6 0 17 2014 72.5 0 - 1983 72.5 0 18 1969 72.4 0 19 2017 72.2 0

Another endless summer pattern in September or October transitioning to a little below average in November.

As long as we can line up some decent conditions for a rogue snowstorm or two by February not overly concerned about what happens early on during most El Niños. Don’t mind delayed as long as it isn’t denied.

Yeah, looks like the model blend has the first possible freeze of the season in NYC for tomorrow morning.

It looks like the early part of December features dual forcing from the Maritime Continent back to just east of the Dateline. Not that I put a ton of stock in these extended weekly model extensions, but the GEFS finally has some east based forcing in late December like we saw in 97-98. This time period is still highly speculative. But the model may be responding to the sharp increase in Nino 3 SSTs.

Yeah, very warm and dry November for the CONUS outside the Northeast.

Happy Thanksgiving to everyone. We may have to be patient for our first snowfall. Very slow start to the season so far across the US.

That is a very good question. I am more in the warmer winters have become more frequent camp since the super El Niño. But we don’t have enough data yet to say it has become permanent. It’s just that the warming WPAC and Western Atlantic have loaded the dice for more warmer outcomes. I still think we’ll eventually get another cold winter in the Northeast. Just that it won’t quite be to the magnitude of what we saw during recent cold winters like 14-15 and 02-03. To get a colder pattern I think we would need to get more of a 500 mb type +PDO pattern like we got in January 22 over several months. I am still trying to figure out how we got that pattern with such a strong -PDO. But my guess is that there is a section of the WPAC near 15N that can override the warmer signal that usually dominates when the entire WPAC is so warm. That is what some of the papers said after the 13-14 and 14-15 winters. I would also like to know why that 13-14 and 14-15 record Western ridge pattern has shifted to the warm season instead of winter leading to record heat and drought out West. So in short, I don’t really know how we could confidently forecast a cold Northeast winter ahead of time absent a strong +PDO and Modoki signature like we got in 14-15. Our next cold winter may just turn out to be a pleasant surprise when forecasts goes warm again. Though it’s possible someone will find an early season signal and go cold and get it correct.

They estimated from a tree ring study that the 1960s drought was the worst in 400 years. https://seaandskyny.com/2012/04/29/trees-tell-the-story-of-500-years-of-nyc-drought-history/

That early December snapshot looks a lot like last December with a Greenland block and hostile Pacific. But hope we have a better chance at getting lucky due to an undercutting Nino STJ. If not in December then later in the season if we can hold the Greenland block.