bluewave

I shifted the map closer to the Northeast so we could see the finer details. While the 2020s are still young, our strong -AO blocking Decembers of 2022 and 2020 were much further south than their counterparts from previous decades. December 2022 was the furthest south block on record with a monthly -AO value lower than-1.5 and -PNA for the month. Same goes for December 2020 which was furthest south based for a +PNA. We could expand to compare January 2021 which had an -AO block lower than -1.5 which was further south based than previous decades. We could also include other months of the year but not enough space in this post to compare. 2020s December -AO -PNA Earlier -AO -PNA December 2020 -AO +PNA Earlier -AO +PNA

I think part of the issue we see on wx twitter is the tendency for people to give long range ENSO models the same weight as a short term model forecast. I have been pointing out since last spring the warm bias these ENSO forecasts have been exhibiting for years. It’s OK to question a models output which makes for a much better forecast. Plus this warm bias has become more evident in the recent era of the seemingly perma-Niña background state.

The bottom line is that 70° Septembers and 60° Octobers have become more common. Same goes for 50° Novembers and 40° Decembers. In the old days we had the coldest Septembers which were closer to 60° and Octobers which were near 50°. The most extreme version of this was the 50° December 2015 which would still rank near the warmest on record for November. So our monthly temperatures continue to shift closer to places like Norfolk and DC. The good news for us is that we can adapt to a climate closer to Virginia.

So why are you ignoring the posts from the CPC stating that there is only a 30% chance of a super El Niño due to the much lower upper ocean heat anomalies?

It’s all about proportionality. Sure it feels chilly out there this morning. But the cold is nowhere near a record. Highs in the low 80s later this week is near the record. We would need lows in the 20s to set a record. That’s what people are saying. Several of our recent winters since 15-16 were near the warmest on record. But even a winter averaging around or over 40° or warmer feels chilly outside and you will still need a jacket on most days. Newark Area, NJVersion: 18.2 (created 2023-09-05)Period of record: 1893 through 2022DateLowest minimum temperatures (degrees F) 10/25 31 in 1907 31 in 1903 33 in 1939+ 10/26 31 in 1952 31 in 1936 31 in 1933+ 10/27 27 in 1936 29 in 1976 29 in 1907 10/28 25 in 1936 27 in 1904 29 in 1976 10/29 29 in 1904 30 in 1965 30 in 1940 10/30 31 in 1952 31 in 1910 31 in 1902 10/31 27 in 1904 29 in 1975 30 in 1910+ Newark Area, NJPeriod of record: 1893-01-01 through 2023-10-22DateHighest maximum temperatures (degrees F) 10/25 79 in 2001 79 in 1963 78 in 2021 10/26 79 in 1964 79 in 1963 78 in 1989+ 10/27 81 in 1963 80 in 1947 78 in 1989 10/28 82 in 1984 81 in 1919 78 in 1989+ 10/29 78 in 1971 78 in 1946 76 in 1989 10/30 82 in 1946 80 in 1961 80 in 1950 10/31 82 in 1946 79 in 1950 77 in 1945

Nino 3.4 is struggling to get much past the 1.6 to 1.7 range on the dailies with the upper ocean heat so much lower than other strong El Niños. So the October daily peak was similar to September. Most El Niños show a decent jump from September to October. So the Euro seasonal is going to have one of its biggest misses on record for an October average forecast of 2.03. The CFS is actually going to be closer to the mark for its October forecast of 1.60. The current monthly average from OISST is 1.53. ECMWF 2.03 NCEP CFSv2 1.60 Current October OISST average 1.53.

Yeah, I had several posts showing the more south based based blocks with the warmer Atlantic SSTs in recent years. Also the tendency to get near record -AO months like last December with the NAO hardly going negative. The SW lean to the blocking is causing very large spreads between the AO and NAO. Some implicated the -PNA last December. But there were months in the older era with even deeper -PNAs that coincided with -AOs and colder NATL SSTs with blocks that didn’t build so close to New England. December 2022 2nd lowest December -AO on record behind 2009 and more south based block with the NAO hardly responding. AO -2.719 NAO..-0.15

Yes. The record NATL SSTs are probably the reason for the more south based blocking down to New England in recent years.

El Niños are usually cooler in the Southeast than the CPC and Euro seasonal. The colder departures further SW are more related the expectation on the Aleutian ridge north of Hawaii. This tends to promote downstream troughing near the SW instead of SE. Need a stronger Aleutian low north of Hawaii to keep the ridging near the East Coast in check.

That’s why I am not a big fan of the Aleutian ridge north or northwest of Hawaii. This persistent pattern for much of the last 8 winters tends to lower heights over the Western US and pumps the ridge in the Northeast. While the Euro seasonal raises the PNA in Canada, it still has the trough axis tucked underneath in the SW. The one hope is that we can cash in during any +PNA -AO intervals for a better snowfall outcome than last winter around NYC. But it would still be a record 9th warmer than average winter in the the Northeast if the trough axis remains near 115 west.

Yeah, the magnitude of the warmth increases the further north you get.

The warm departures on the warmer days will be more impressive than the cold departures on the colder days. That’s how the Northeast is on track for several stations having a top 10 warmest October. While the colder days have felt more fall-like, there has been no top 10 or record cold for this time of year.

We get the highs approaching 80° while Montana goes below 0°. Same old pattern of recent years with the cold dumping into the West. Plenty of time for the cold to moderate coming east. But we’ll still probably get 30s around NYC which will feel much colder following 80°.

I like the ensemble means better since those tercile maps lack the better definition.

The main challenge with the Euro seasonal is that it still has a trough near the SW in February. So storms ejecting from the SW could come out too far north without solid blocking on the Atlantic side. But I would still take my chances with that look compared to last winter. While it would be a record 9 warmer winters in a row for the Northeast, the snowfall would probably be better than last winter.

Even the Canadian which can sometimes have a cold bias has 80°.

Looks like the CPC is going with the Euro seasonal which has the warm Nino +PNA ridge to the north undercut by the -PDO trough near the southern Rockies. With a +PDO El Niño the trough would be over the Southeast. But it’s pulled west due to the -PDO in the seasonal forecasts. If we see the same error as the seasonal forecasts last winter, then the trough out West will be deeper pumping the ridge more in the East. You can see the Euro seasonal maintaining the Niña -PDO ridge north of Hawaii. But it also has the Nino +PNA ridge in Canada. Need to lose the -PDO and ridge north of Hawaii for the El Niño to be able to be the main driver.

It has been a split flow pattern. But the northern branch looks to dominate next weekend with the strong -PNA pattern. So some late season Niña-like 80° heat possible for the Northern Mid-Atlantic.

Models now indicating record 80° heat possible for next weekend. Maybe we can finally break the streak of rainy weekends. This would be the warm and sunny weekend which was so elusive all summer. Newark Area, NJPeriod of record: 1893-01-01 through 2023-10-21DateHighest maximum temperatures (degrees F 10/28 82 in 1984 81 in 1919 78 in 1989+ 10/29 78 in 1971 78 in 1946 76 in 1989 10/30 82 in 1946 80 in 1961 80 in 1950

The actual 500 mb pattern this month is classic MJO 6 with the deep Scandinavian trough and Hudson Bay ridge. I guess we can chalk it up to atmospheric lag since the MJO has been stuck in phases 4-6 for so many years. It’s as if the atmosphere isn’t even registering the subsidence near the Maritime continent with the near record +IOD.

The much lower upper ocean heat than usual for a strong El Niño is causing Nino 3.4 to struggle to push past +1.7 over the last month.

Blocking near Hudson Bay is classic La Niña in October. But this is even extreme for a La Niña. Somewhat similar to the La Niña in 2021. So not a very Nino-like North American pattern this October.

The first time the upper ocean heat anomalies during a developing El Niño were +.40 warmer in June than October. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

Relative to the means, the warm up next week will be more impressive than the cool down.