bluewave

While the CFS may be exaggerated in its decline, the drop in OHC may be we we see the slight decline and leveling off effect. Not many cases to draw from with and OHC decline from 1.4 in June to under +1.0 in late September. Not sure how much warmer we can get with a break in momentum like this.

October is another rapidly warming month from the old days like September has been. The monthly temperature increases from 81-10 to 91-20 have been more pronounced during certain months. Newark and Islip are compared below. The +1.0 or warmer months for either station were bolded. ……….EWR…..ISP Dec…+1.5….+1.5 Jan….+1.2…+1.3 Feb….+0.5….+0.5 Mar….+0.4….+0.6 Apr….+0.5…..+0.6 May...+0.6….+0.9 Jun….+0.3….+0.6 Jul…..+1.4…..+1.1 Aug...+0.6….+0.9 Sep….+1.0….+1.3 Oct…..+0.9..+1.4 Nov….+0.2..+0.5

Relative to the historic rankings, the warmest departures shifted over closer to the Dateline in August. Some areas in that zone had the warmest August SSTs on record. Same goes for the warm pool east of Japan. But the overall warmth of the entire WPAC is still there. We have seen month to month fluctuations across different zones of the WPAC in recent years. Big decline with the IOD in the fall of 2019 followed by rapid rebound in the winter. So this part of the basin keeps finding ways to maintain its heat even with short term fluctuations. Quite an extensive reservoir of +30C SST warmth.

It’s no secret that the warmth imbalance to the west is keeping the trades up and letting the Nino 3.4 SSTs decline a bit in recent days.

The resolution on those charts is pretty poor. The WPAC is very warm for this time of year. Plus it’s much warmer than all the previous very strong El Niño years. Also notice the unusual -PDO signature for such warm ENSO SSTs. Nino 4 is close to all-time record warmth for this time of year.

That historic marine heatwave east of Japan is probably helping to push the -PDO to even lower values than we saw during last fall. A daily reading of -2.6 must be near the record lows for this date. Hoping we don’t see some odd combo going forward of higher Canadian heights from the Nino and a Western Trough tucked underneath like we see with -PDO patterns. That would lead to a stronger NPAC Jet pushing the +PNA ridge too Far East and possibly overshadowing the STJ. Want to see the STJ dominate with some decent blocking for the NE snowfall fans. https://s2s.worldclimateservice.com/climatepanel/

I am not sure. But the biggest influence study I found was with the IOD back in 2019 which was twofold. That event had very intense Western-Central IO forcing which is believed to have driven the raging SPV and +NAO pattern that winter. But so far, we aren’t seeing anything like that forcing this year. Maybe related to the much warmer SSTs near SE Asia. The other factor to be aware of is rapid SST recovery near Java in December. That was associated with the MJO 4-6 wave in December 2019 which warmed what started as a cold December as the month progressed.

There isn’t as much interest in the DMI for us since it peaks before our winter starts. It’s usually a bigger story for people in that region. But sometimes the rapid recovery if the SSTs around Java can enhance unfavorable MJO phases for us. So that always bears monitoring.

I would just note that the entire area around the WPAC into the Eastern IO is much warmer than at the same time in 2019. So we can’t expect to see the same outcomes as that year. These competing marine heatwaves add a new level of complexity to the forecast patterns. So we can’t just rely on the old correlations under colder SST eras. Using just one index like Nino 3.4 or IOD exclusively in this new era just isn’t going to cut it anymore.

There are a few differences here. Cycles, oscillations, and teleconnections, will always exist whether the climate is warming or not. But there have been an increasing number of studies linking changes to these climate modes as the climate warms. So in effect we get the steady background warming combined with the familiar patterns warming also. So when these intersect, we can get such an extreme pattern of warmth like in the PAC NW summer 2021 that it surprises many. But we can look at waves in the ocean and and see how this happens when they combine. These extreme weather and climate events are akin to constructive interference with rogue waves in the ocean. Just substitute atmospheric Rossby wave behavior. Also these more stuck weather patterns seem to lock in in warmer states like standing waves. The other challenge is that our climate is changing faster than the technology that creates the regional climate models. Plus waiting 30 years to confirm a pattern or trend doesn’t help when we need to forecast extreme events on much shorter time scales.

My guess is that that the timing is somehow related to these frequent December MJO 4-6 intervals which have been increasing in duration and intensity in recent years. But we would probably need a formal study which hasn’t been done yet.

Nobody is making light of the implications considering the historic and rapid global temperature rise in recent months. This is the first El Niño year with so much planetary warming in the early months of the event. Past instances like 15-16 were later in the winter. Whether the atmosphere has been in La Niña or El Niño, both 22-23 and 15-16 both tied for 2nd warmest Northeast winter. We recognize how every winter since the 15-16 super El Niño has been warmer to record warm. So our questions with this El Niño vs competing La Niña influences are strictly about any snowfall potential, STJ vs NPAC Jet, +PNA vs-PNA intervals, WPAC warm pool, MJO, ambient record NATL SSTs etc…

The real mystery is why the rate of December warming during recent decades has accelerated around the solstice at a number of Northeast stations in relation to the rest of the month? So we get the annual spike in temperatures leading up to holiday periods each year. This has been especially pronounced around the NYC Metro. It also shows up at stations further north. 1981-2022 December temperature change by time of month NYC….12-1 to 12-15…..+1.4……..12-16 to 12-31….+3.8 ALB…12-1 to 12-15…..+3.2………12-16 to 12-31…..+5.4

Since the warmer December pattern emerged in the Northeast most noticeably in 2011, our only two cold teleconnection years were 2017 and 2013. Those required strong 500 mb -EPO blocking. But it was by far the rarest teleconnection pattern pattern of the last 12 Decembers. So we are running 10 warmer to record warmer to only 2 colder with no cold ranking records. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/regional/time-series/101/tavg/1/12/1895-2023?base_prd=true&begbaseyear=1981&endbaseyear=2010 Northeast December temperature departures 2022….+1.2…..La Niña 2021…..+4.5….4th warmest….La Nina 2020…+3.2….17th warmest….La Nina 2019…..+1.3….weak warm ENSO 2018….+1.6…..El Nino coupling issues 2017….-3.5…..La Niña 2016….+0.6….La Niña 2015…+11.7….1st warmest..Super Nino MJO46 2014….+3.9….14th warmest…weak El Nino 2013….-1.1…….Neutral 2012…+4.7….10th warmest…Neutral 2011….+5.0….8 th warmest….La Niña

We got a Niña background in December 2015 which was warmer than any previous December by a wide margin. Perhaps it was the interaction with the super El Niño that made it so extreme. The one paper on the event was focused on the strong MJO 4-6 which was the first for a super El Niño. We had mixed forcing elements in December 2018 with a Nina-ridge north of Hawaii and an eastward displaced +PNA El Niño ridge in Canada. But NYC did get the colder front loaded La Niña start to December before the warmer MJO 4-6 kicked in during the mid to later portion of the month. So we don’t have a great sample size of competing Niña-like influences December patterns in El Niño years since the super El Niño in 15-16. Dominant La Niña or El Niño patterns will usually be great in December with blocking like we saw in the 2009 Nino, 2010 Niña, and 2020 Niña. But last December was disappointing with a strong La Niña background and 2nd strongest -AO. So we missed out on the frontloaded La Niña period in December before the warmer mid to late winter Nina portion arrived. Decembers have really struggled to produce wintery weather for us regardless of ENSO or degree of coupling since 2011. Maybe it’s a shorter winter thing in warmer world when December sometimes act like a late fall month rather that early winter. Sometimes a great March can make it feel like we are getting our 2nd or third winter month.

6th lowest annual daily minimum extent. Most of the daily minimum extents have been in the 4s since the lower Arctic ice sea era began in 2007. 12 finishes in the 4s…3 in the low 5s…and 2 in the 3s. https://nsidc.org/arcticseaicenews/2023/09/arctic-sea-ice-minimum-at-sixth/ 1 2012 3.39 1.31 Sept. 17 2 2020 3.82 1.47 Sept. 16 3 2007 2016 2019 4.16 4.17 4.19 1.61 1.61 1.62 Sept. 18 Sept. 10 Sept. 18 6 2023 4.23 1.63 Sept. 19 7 2011 4.34 1.68 Sept. 11 8 2015 4.43 1.71 Sept. 9 9 2008 2010 4.59 4.62 1.77 1.78 Sept. 19 Sept. 21 11 2018 2017 2022 4.66 4.67 4.70 1.80 1.80 1.81 Sept. 23 Sept. 13 Sept. 19 14 2021 4.77 1.84 Sept. 16 15 2014 2013 5.03 5.05 1.94 1.95 Sept. 17 Sept. 13 17 2009 5.12 1.98 Sept. 13

Yeah, Saturday was the 4th coldest high temperature departure of the year so far at HPN. Anytime we get at least -10 for high or low departure it really stands out these days. Data for WESTCHESTER CO AP, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Departure 2023-02-04 -16.1 2023-02-25 -15.3 2023-04-29 -14.4 2023-09-23 -12.7 2023-05-03 -10.7 2023-08-24 -10.2 2023-04-28 -10.1 2023-05-04 -10.0

All we can say that is the summer matched a warmed up weak El Niño MEI composite. September has had mixed El Niño and La Niña influences. So it wouldn’t be a surprise if we see more back and forth going forward like the models show. Obviously, El Niño winters are typically backloaded for their best effects. So it’s still way too early to know how the typically best part of the winter plays out. Our sample size of El Niño experiences since the WPAC warm pool has greatly warmed is pretty small. 15-16 was well coupled and we still got a Niña-like month in December before the heart of the season. So everything worked out once we got a great El Niño blocking pattern. 18-19 was showing signs from the fall of not being able to couple which carried though the winter. So hopefully we see improved coupling going forward in time for the typical back loaded portion of El Niño winters. Probably a range of possibilities based on competing Nino-like or La Niña influences. Obviously, we would want a clean El Niño pattern to dominate the typically back loaded portion with blocking and a great STJ.

I hear you. When we subtract the strongest El Niño background states from this summer we get a strong -PDO warm pool from Japan across the Pacific. Plus the record Niña-like WPAC warm pool which has been a nearly permanent feature over the last decade. The Atlantic being so off the charts warmer than what we have seen is probably boosting the ACE and weakening the shear from past states with the summer Nino regions were so warm.

I am not sure if it’s the residual forcing or just the very Niña-like SST profile continuing from recent years outside the immediate ENSO regions.

Because the forecast is more of the same for the next few weeks which will take us through the first half of the fall IO period with no strong Eastern Indian Ocean forcing like we got back in 2019.

The IOD mostly influences the Indian Ocean to Australia during the Northern Hemisphere fall when it peaks. When the forcing gets overpowering in the Western IO, it can strengthen the polar vortex and +NAO like we saw from the fall of 19 into the winter of 20. But so far, the VP anomalies over the IO are much weaker than that record breaking event. Weaker IOD fall forcing so far Record IOD in 2019 much stronger forcing signature.

I hear what you are saying about the Euro and EPS. The day 11-15 GEFS looks like it will end up doing better than the EPS. But it’s still showing the -PNA influence in the new day 11-15. We’ll see how it goes. New 6-10 Old 11-15 New 11-15

My one concern is the tendency for the day 11-15 forecasts to default to El Niño climo. But finally see that there will be other competing influences once day 6-10 forecast period arrives. This is how the long range EPS missed the more -PNA in its day 11-15 forecast. So we often have to wait to until day 6-10 in order to see what the actual drivers will be. New day 6-10 run more -PNA and Aleutians Ridge Old day 11-15 defaulting to more +PNA and stronger Aleutian Low

Just add 2° to the NYC September average temperature to compensate for the artificial cooling from the trees. Notice how much warmer the downtown NYC average temperatures have been this month. Even Montauk is several degrees warmer this month. The the new WTC station at Liberty Park is 2° warmer and it right on the water. So the actual temperature in Central Park away from the trees will finish above 70° in September. 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 74.7 NY WORLD TRADE CENTER WBAN 73.9 NJ NEWARK LIBERTY INTL AP WBAN 73.6 NY LAGUARDIA AIRPORT WBAN 73.5 NY MONTAUK AIRPORT WBAN 73.3 NY WEST POINT COOP 73.0 NY FARMINGDALE REPUBLIC AP WBAN 72.2 NJ HARRISON COOP 72.0 NY NY CITY CENTRAL PARK WBAN 71.8 NY JFK INTERNATIONAL AIRPORT WBAN 71.8 CT NEW HAVEN TWEED AP WBAN 71.7