bluewave

The weaker Aleutian low has become a common theme with the persistent La Niña background state following the WPAC warm pool expansion. https://www.eurekalert.org/news-releases/1002264 Wang and co-authors examined 20 La Niña events from 1920-2022 to investigate the fundamental reasons behind the historic change of the multiyear La Niña. Some long-lasting La Niñas occurred after a super El Niño, which the researchers expected due to the massive discharge of heat from the upper-ocean following an El Niño. However, three recent multiyear La Niña episodes (2007–08, 2010–11, and 2020–22) did not follow this pattern. They discovered these events are fueled by warming in the western Pacific Ocean and steep gradients in sea surface temperature from the western to central Pacific. “Warming in the western Pacific triggers the rapid onset and persistence of these events,” said Wang. “Additionally, our study revealed that multiyear La Niña are distinguished from single-year La Niña by a conspicuous onset rate, which foretells its accumulative intensity and climate impacts.” Results from complex computer simulations of climate support the observed link between multiyear La Niña events and western Pacific warming. The new findings shed light on the factors conducive to escalating extreme La Niña in a future warming world. More multiyear La Niña events will exacerbate adverse impacts on communities around the globe, if the western Pacific continues to warm relative to the central Pacific. “Our perception moves beyond the current notion that links extreme El Niño and La Niña to the eastern Pacific warming and attributes the increasing extreme El Niño and La Niña to different sources,” Wang added. “The knowledge gained from our study offers emergent constraints to reduce the uncertainties in projecting future changes of extreme La Niña, which may help us better prepare for what lies ahead.”

The new DJF 500 mb pattern is a blend of El Niño and -PDO composites with the trough pulled further west from the earlier forecasts. So a colder West and warmer East trend from earlier runs. New run blended El Niño -PDO 500 mb composite Old run was more of an El Niño dominant composite

This month will be a good test of the El Niño vs -PDO influence. The key region in October is the EPO. The PNA becomes more correlated in the winter. El Niño Octobers typically have a -EPO pattern. -PDO in October is +EPO. So we can already see the back and forth between -EPO and +EPO in the model forecasts for the month.

Euro seasonal update is trending colder in the West and warmer East as it has a more well defined -PDO pattern for the winter. The main feature of the -PDO is the warm pool and ridge south of the Aleutians. While the Euro doesn’t have great seasonal skill, sometimes it’s trends from run to run provide some skill. New run Old run

We’ll see if the SPC HREF picks up on it once we are within range.

Too much SE flow today here so the most impressive records going north.

Almost Looks like a PRE or inverted trough associated with Phillipe as he interacts with the trough. We’ll probably have to wait until this gets within the range of the CAMS to see if this feature is real.

Record heat today on Long Island. We haven’t had an October record low on Long Island since 2003. Good early signal for the record cold that followed in January 2004. Reynolds Channel between Long Beach and Island Park was nearly frozen all the way across near the bridge.

Another outstanding job by this model with the September average extent finishing at 4.37 million sq km. This is nearly identical to the forecast of 4.46 million sq km issued back in June based on May melt pond data.

Not even sure what type of forcing we would need to get in order to break this streak of 8 warmer winters in a row for the Northeast. 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

The only Nino region to have a new record in September was 4 getting close to +30C.

More possible beach erosion with the new moon next weekend if the storm can develop enough. Then some of the highest astronomical tides of the fall with the full moon near the end of the month. That’s one period when any possible coastal storms would only need a +0.75 surge for minor, +1.75 for moderate and +2.3 to +2.5 for low end major coastal flooding.

Looks like we keep the rain on the weekends theme for a while longer. Rain with the cold front this weekend. Then another storm possible for next weekend.

Record warmth to start October as EWR and HPN tied their record highs. Data for October 3 - NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation Snowfall Snow Depth 2023-10-03 85 59 0.00 0.0 0 1950-10-03 85 61 0.00 0.0 0 2021-10-03 84 56 0.00 0.0 0 2002-10-03 84 63 0.04 0.0 0 1968-10-03 83 65 0.04 0.0 0 1967-10-03 83 53 0.00 0.0 0 Data for October 3 - WESTCHESTER CO AP, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation Snowfall Snow Depth 2023-10-03 80 54 0.00 M M 1983-10-03 80 60 0.00 0.0 0 2000-10-03 79 M 0.00 0.0 0 2006-10-03 78 49 0.00 M M 2001-10-03 78 51 0.00 M M 1968-10-03 78 63 0.02 0.0 0 1953-10-03 78 44 0.00 0.0 0

It is interfering with the strong WWB pattern we usually see during Septembers with -SOI. This is probably due to the lower pressures than average north of Australia.

That PDO is so negative that it’s probably destructively interfering with El Niño development as seen with the stronger trades and Nino region temperature declines in recent weeks. https://earthscience.stackexchange.com/questions/966/why-is-the-warm-phase-of-the-pacific-decadal-oscillation-associated-with-stronge According to the State Climate Office of North Carolina webpage Global Patterns - Pacific Decadal Oscillation (PDO), experts believe Essentially, almost analogous to constructive and destructive interference in sound. Another relationship, from the University of Alaska, Fairbanks webpage The Pacific Decadal Oscillation also asserts that

It’s very difficult to get two consecutive winters that warm since the Northeast tied with 15-16 last winter. Even though last winter was just as warm as 15-16, we didn’t get an extreme +13 month. 16-17 was still one of the warmest after 15-16 but there was a step down by about 1° cooler. Warmest Northeast winters list

Every year plays out differently especially with all the competing influences now. But September 2012 was the only time we had a -PDO under -2.00 with the attempted El Niño development. We can remember the El Niño weakening in late September with the resurgence of the trades after some summer WWBs.

This is currently a split flow pattern with the PAC Jet dominating over the STJ. That big jet extension all the guidance is showing is what we usually see with La Ninas this time of year. So the -PDO pattern is really pushing back against the El Niño development at the present time. The firehose jet will give cause the -EPO to flip to an +EPO and erode the +PNA ridge.

If we don’t get a strong WWB pattern this month, then we probably have already seen the peak of this event. But even a stronger WWB pattern may only get us back to where we were a few weeks ago. There is only so much more we can warm without a big turnaround in OHC and WWBs. This kind of sudden falloff in SST departures from Nino 1+2 to 3.4 hasn’t happened before from these high levels in late September into early October. But it did happen with the 12-13 El Niño attempt from much weaker levels.

It’s because they are measuring the high temperatures now in NYC underneath trees. The thermometer was out in the open before the 90s. So this invalidates comparisons to NYC high temperatures before the change in observation methodology. Just add a few degrees to the NYC high temperatures and they would have as many top 10 warmest finishes as the other sites do. Even the new WTC station right on NY Harbor with local sea breezes finished the month above 70°. https://facilityexecutive.com/world-trade-center-weather-station-offers-insights-for-facilities/ Monthly Data for September 2023 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Mean Avg Temperature NY PORT AUTH DOWNTN MANHATTAN WALL ST HEL ICAO 71.7 NJ NEWARK LIBERTY INTL AP WBAN 71.2 NY LAGUARDIA AIRPORT WBAN 71.0 NY WORLD TRADE CENTER WBAN 70.4 NY MOUNT SINAI COOP 70.2 NY MONTAUK AIRPORT WBAN 69.9 NY FARMINGDALE REPUBLIC AP WBAN 69.8 NY MOLLOY CERCOM COOP 69.5 NY NY CITY CENTRAL PARK WBAN 69.4 NY JFK INTERNATIONAL AIRPORT WBAN 69.4 NY RIVERHEAD RESEARCH FARM COOP 69.4

Which goes to the importance of getting a strong WWB pattern to drive the El Niño development. This key ingredient was missing in September. Notice how much stronger the WWB pattern is during typical Septembers when we have a developing El Niño.

It’s more impressive if we include all the Friday to Sunday periods going back to June 1st. There were only 2 extended weekends since then with no measurable rainfall in NYC. So NYC went 16 out of 18 extended weekends with a least one day recording measurable rainfall. NYC Friday to Sunday rainfall since June 1st JUN….2-4…0.24 JUN….9-11…0.01 JUN….16-18…0.23 JUN….23-25…0.11 JUL…..30-2….0.58 JUL…..7-9……0.98 JUL…..14-16….1.84 JUL…..21-23….0.15 JUL…..28-30….0.06 AUG…..4-6……T AUG….11-13….0.69 AUG….18-20….0.77 AUG….25-27…0.96 SEP….1-3….0.00 SEP….8-10…1.92 SEP…15-17…0.23 SEP…22-24….2.21 SEP….29-01….5.52

While I loved living in Long Beach, they were always having mismanagement issues that lead to tax increases. They have been having some big financial struggles since Sandy. The locals aren’t happy that they are planning a very large ocean front condo and apartment complex. They are worried about more tax increases and stress on the infrastructure. Just too much development packed onto a very small island.

The oddest juxtaposition is getting such a low -PDO with such historically warm SSTs near the Dateline. Those two competing patterns may try have a Nino-like ridge building over Western North America only to get a Niña-like WPAC jet extension to try and knock it down.