bluewave

The historic snowfall outcome in March 2018 for places like Long Island was one of the rare benefits of the rapid WPAC warm pool expansion. The record amplitude MJO 6 drove that SSW and March snowfall extravaganza. I would love to see more months like that was the WPAC warms. But they have been in the minority in recent years. https://wcd.copernicus.org/preprints/wcd-2020-17/wcd-2020-17-manuscript-version3.pdf SSW2018 occurred under the favourable conditions of the easterly phase of QBO, La Niña phase of ENSO and followed the MJO phase 6 with the largest amplitude in observational record (from 1974 to 2018) (Barrett, 2019). Barrett (2019) showed that the large-amplitude MJO episode in 2018 affected weather in the north-eastern United States under the conditions of strengthened Rossby wave teleconnections between the tropics and the extratropics. Furthermore, SSW2018 was preceded by a record-breaking meridional eddy heat flux at 100 hPa observed before an SSW since 1958 (see Fig. A1 in Appendix A, also pointed out by Ayarzagüena et al., (2018)).

Yeah, this has been the case frequently since the super El Niño. Missing a colder storm track in late November isn’t that big a deal since even a colder track is facing more marginal snowfall climo especially near the coast. But during the winter it’s a completely different matter. Missing the colder storm track last December with that last minute Southeast ridge pop up was a complete waste of the 2nd lowest December monthly -AO on record. Then we had the Christmas major flash flooding with that warmer track right after the 40” event in BGM in December 20. People said that it was understandable that December 2015 would be warm anyway since it was a super El Niño. But no other super El Niño produced a +13 winter month and an historic Southeast ridge like that. Plus we had the historic MJO 4-6 for a super El Niño. Then we heard how the February 2018 historic warmth and Southeast ridge was just the La Niña climo for February. But the 500 mb height anomaly in the Northeast was higher than any previous date for the entire winter season. And it was our first 80° reading in February. In 18-19 we heard how the El Niño was just too weak to couple and it was no big deal. But many weaker El Niño’s had no trouble coupling. That Aleutian ridge-Southeast ridge in 18-19 was not normal for even a weak El Niño. The strong Southeast ridge last winter got blamed on the -PDO. But most -PDOs from the earlier era had much weaker Southeast ridge patterns especially when the AO was negative.

The models usually struggle around this time every year trying to get the December pattern correct.

One day is all you need to force a warmer storm track.

In this case it is as the previous runs with less of a Southeast ridge this week didn’t have the La Niña-like forcing near the Maritime Continent. All it takes is for a small amount of forcing in the MJO 4-6 regions for the Southeast ridge to develop. It may not even show on the RMM charts but it’s there on the VP anomaly charts. New runs more Southeast ridge and Maritime Continent forcing Old runs less Maritime continent forcing and Southeast ridge

The NDFD gets NYC down to 33°-34° with widespread 20s in the suburbs.

Maybe we can sneak in a dry Thanksgiving weekend as the Euro and GFS suppress the southern stream low. The CMC still has the storm. But these split flow patterns are very tough for the models.

Tonight looks like it may be the coldest night of the fall so far in NYC. The MOS is down to 34° and some models have 33°. Then the temperatures rebound. What was supposed to be a Thanksgiving cooldown now has highs in the low 50s for NYC which is pretty much close to average.

What we are seeing this week is just more back and forth. The coming -EPO +PNA is more El Niño-like. But the occasional Southeast ridge and warmer storm track next few days is classic La Niña. So my guess is that the El Niño and La Niña influences will continue to compete for influence. This back and forth has been going on since last spring.

All this talk of how strong the El Niño is getting is pretty much moot since it’s still not well coupled with the mid latitude pattern across the North Pacific and North America. The November pattern so far is much closer to the La Niña composite with and Aleutian Ridge and secondary ridge near the Southern Rockies and Plains. The cooler trough near New England is also a November La Niña pattern. The persistent La Niña background state is one reason that November is one of the few months out of the year with cooler departures located near the Northeast. Most other months of the year have been near to record warm.

I have been pointing out how warm the area from the Dateline back to the WPAC has been since last spring. That’s why I though it was unlikely that this would follow the trajectory of a big east based event like 97-98. So now we have +30C near the Dateline and around the Maritime Continent. That’s why we are seeing the forcing back and forth between those regions right now.

I would say the fall pattern has been a blend of La Niña and El Niño influences.

https://www.nature.com/articles/s41558-023-01801-6 Understanding the recent increase in multiyear La Niñas Abstract Five out of six La Niña events since 1998 have lasted two to three years. Why so many long-lasting multiyear La Niña events have emerged recently and whether they will become more common remains unknown. Here we show that ten multiyear La Niña events over the past century had an accelerated trend, with eight of these occurring after 1970. The two types of multiyear La Niña events over this time period followed either a super El Niño or a central Pacific El Niño. We find that multiyear La Niña events differ from single-year La Niñas by a prominent onset rate, which is rooted in the western Pacific warming-enhanced zonal advective feedback for the central Pacific multiyear La Niña events type and thermocline feedback for the super El Niño multiyear La Niña events type. The results from large ensemble climate simulations support the observed multiyear La Niña events–western Pacific warming link. More multiyear La Niña events will exacerbate adverse socioeconomic impacts if the western Pacific continues to warm relative to the central

That the power of even a little forcing near MJO 4-6 around 120 E to pump the Southeast ridge. New run Old run

Looks like NYC continues to miss the freezes with the weak CAA and light winds. Thanksgiving should be a nice day for travel with seasonable temperatures. Good that the rain is coming in ahead of the holiday and after.

It’s pretty rare that we get any decent frozen precip events along the coast in late November with a piece of the trough hanging back over the SW.

So we get a battle between the Nino-like +PNA -EPO and Niña-like Southeast ridge around Thanksgiving.

You can already see the forcing back and forth this month.

It’s really a +30C forcing battle between the Maritime Continent and the area around the Dateline as the IOD is rapidly fading with big SST increases in MJO 4-6.

Yeah, much better pattern on Long Island than points further west.

That was still one of my favorite snowfall seasons. Probably the greatest Euro control run in history. The 950 mb benchmark blizzard could be the last time one of these Lockitin posts actually verified. https://www.weather.gov/okx/Blizzard_Jan42018

The 17-18 winter was +1.1 warmer than average due to the record 80° warmth in February. So the cold departures from December into January got erased by the big +6.1 departure in February. 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

We have had snow droughts before, but never an 8 winter cold drought before.

Yeah, the most impressive Arctic outbreak since 15-16 went to our west in February 2021. The February departures weren’t low enough for the winter to average colder than normal. So we go into this winter with a record 8 warmer than average winters in a row. A record breaking 8 warmer than normal winters in a row since the 15-16 super El Niño. 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