bluewave

The funny thing is the Euro did a great job with the U.S. summer temperature forecast. But the forecast of over 20 named storms and 200 ACE was too high in the tropical Atlantic. So it’s interesting that the model can hone in on one set of circumstances but completely miss another. As for next winter, we would need some type of mismatch which would mute or shift the predominant -PDO pattern all the seasonal models have. So not sure if what happened in the Atlantic will be relevant beyond some extra SST warmth and fewer wave breaking events in the North Atlantic from a large number of tropical systems. My guess is that the very high ACE years created these wave breaks which lead to more -NAO development and better snowfall outcomes. But we are missing that this year so far. We would need some type of big mismatch for next winter to shift off of this type of look. This summer featured one of the strongest ridges south of the Aleutians and near New England .So the seasonal models really focus in on the Aleutian Ridge and Southeast Ridge next winter. But as always we’ll need to see what actually happens with the atmosphere next winter to know if the models are onto the correct idea. At the very least it looks like this will be our 10th warmer than normal winter in a row for the Northeast in places like NYC. But the details including the magnitude of the warmth and how much snow are difficult to guess at before we get more clues in the coming months.

First time since 1968 with no Atlantic named storm formations between August 13th and September 3rd which was a developing moderate El Niño summer into winter.

The record heat in Japan and adjacent marine heat wave have been two of the more extreme heat records last few summers around the world. It’s why this -PDO has been more defined by the warm pool in those areas a rather than the cold pool so far near the NE PAC. To have two consecutive summers with this big a jump above any previous records is very impressive.

We probably could have challenged the 2012 extent record if the record blocking this summer was closer to Canada and Greenland like in 2012. The 500mb block back in June was the strongest ever recorded for that part of the world for the month. But it shifted closer to Svalbard later in the summer and spared Greenland and the Canadian Arctic.

The JMA winter 2013-2014 forecast issued in October 2013 was one of the best ever for a seasonal model forecast. JMA October 2013 forecast https://ds.data.jma.go.jp/tcc/tcc/products/model/map/7mE/map1/pztmap.php Verification

Canadian high pressure should dominate this week with good radiational cooling in the outlying areas. But it appears that we are back to the measurable rain on weekends pattern. Looks like the frontal passage this past weekend will occur again next weekend. Comfortable temperatures and humidity running below average for early September.

Even though the Euro will likely turn out to be too high with the forecast for 20-25 named storms and over 200 ACE, the U.S. temperature forecast for the summer was very good. So this tells there are elements of the climate system that these seasonal models can handle an others they can’t. It will be interesting to see if the Euro does as well with its winter temperature forecast and 500mb pattern next few updates on the 5th of each month.

One of the reasons the Atlantic has been so quiet last few weeks is due to the ITCZ shifting north into the Sahara.

It’s the first time in known history that a El Niño summer ahead of a winter ONI of +2.0 or greater had 7 named storms and 2 category 4 hurricanes develop between August 20th and 31st to be followed by a developing La Niña the next summer with no new storms during this period. 2023 New developments between 8-20 and 8-31 TS Gert TS Emily Cat 4 Franklin TS Harold Cat 4 Idalia TS Jose TS Katina 2024 No new developments

This is an unusually strong MJO 5-6 pattern for early September. It’s one of the few times of the year when we get a cooler to closer to normal temperatures from these phases. So a nice change from recent early September patterns which have been much warmer.

This looks like it will be one of the strongest -PDO summers since 1950. The -PDO pattern was so strong that year that it produced a +13.0 January in Atlanta. While this is not meant to be a forecast for next winter, it just shows what is within the range of possibilities should we get a strong enough Aleutian ridge and deep enough trough out West. We already had a +13.2 with the 21-22 La Niña and -PDO at DFW in December 21. Extreme months like this usually pop up in forecasts very close to the time period. So it’s not usually something that we can forecast from so far out. Hopefully, we get some type of mismatch pattern next winter that takes an extreme winter month off of the table. But it’s something to just be aware of with such extreme -PDOs. https://www.ncei.noaa.gov/pub/orders/IPS/IPS-017CC821-F4F4-4CF6-868A-42E597844BF5.pdf

The atmosphere is becoming so moist that we don’t even need a tropical storm or hurricane to produce this type of extreme flash flooding anymore. We began to see this back in August 2011 when another unnamed low pressure system with training thunderstorms produced more impressive flash flooding in spots than Irene did a few weeks later. The same went for the unnamed system at Islip in August 2014.

Historic warmth for Svalbard.

The forecast from a week ago was actually pretty good. This weekend was always about a front coming through. The only difference is the front slowed down a little from the forecast last Saturday. New run Old run

We are on track for one of strongest -PDO summers on record as the daily index declines again. 2024 -1.55 -1.33 -1.52 -2.12 -3.00 -3.16 -2.97

Back to back top 10 wettest summers for me. Time Series Summary for NEW HAVEN TWEED AP, CT - Jun through Aug Click column heading to sort ascending, click again to sort descending. 1 2009 17.52 0 2 2006 17.45 1 3 2011 17.38 0 4 1972 16.54 0 5 1955 15.30 0 6 2003 14.55 0 7 1952 13.87 0 8 2024 13.77 1 9 2023 13.45 2 10 1950 13.08 0

Yeah, looks like this was the first time that HVN had 30 days with a 75° or higher dew point.

You are missing the point. We are discussing what has already happened and the strengths and weakness of the approaches used over the last decade since the 15-16 super El Niño. You should cut the scientific climate and weather forecasting community some slack since these changes to our climate are happening faster than some of our older technology based models can keep up with . People are just doing the best they can with the technology we have available at the time. The weather and climate is an open and transparent system where everyone can see the results. Big pharma is different since it’s always not immediately obvious whether all the results of a study have been disclosed. So you are making an apples and oranges comparison.

The AMO itself may not be as relevant to the overall North Atlantic SSTs if we continue to see these subtropical record warm blobs east of New England and the Canadian Maritimes. It could result a the shift in tropical cyclone tracks with some areas seeing more activity and other less. But it will be interesting to see how things go in coming decades. https://www.nature.com/articles/s41598-017-11046-x Over the recent few years, striking changes in Atlantic SSTs have occurred in the subpolar gyre, where the cold anomaly that developed from 2013–2015 was termed the ‘cold blob’ in the press13. This cold anomaly resulted from extremely harsh winters of 2013–2015, characterised by strong surface heat loss14 which resulted in persistent cooling of the upper ocean15 and drove deep ocean convection16, 17. Here, we assess the impact of this cooling on the AMO index, and evaluate the observed changes over the past 3 years relative to the cold AMO period of the 1990s. The AMO index, however, masks any spatial distributions in SST changes, and while the AMO index is negative, the subpolar cold anomaly is accompanied by a warm anomaly in the subtropics. We investigate whether the cold subpolar anomaly is likely to persist and consider how the present cold state of the AMO may evolve.

The Atlantic is still near the warmest on record. The last time there were forecasts for an AMO shift back in 2013 to 2017 the weak cooling only lasted for a few years. Then the SSTs reached record levels over recent years. So this could be an indication that aerosol reductions are playing a role and that the reduction is inhibiting a return to a cooler phase. But we may need a few decades more of observations to confirm. https://link.springer.com/article/10.1007/s00704-022-04207-0 Is Atlantic Multidecadal Oscillation a genuine representation of natural variability in the climate system? Or perhaps is it strongly forced by external drivers? In this paper, a data-driven attribution investigation has been performed for the Atlantic Multidecadal Oscillation (AMO) behaviour in the past via a machine learning technique, NN modelling. We clearly see a forced nature of AMO in the last 150 years, with a strong contribution of the forcing coming from anthropogenic sulphates, which induces its typical oscillating behaviour. The following original application of our model to future predictions of the AMO behaviour shows that it shall probably lose its oscillating characteristic features. The only way to recover them is to consider an unrealistic increase in anthropogenic sulphates in the future under a strong mitigation scenario, and possibly a low-power solar regime. Due to the established influence of AMO on climate and meteorological phenomena in several regions of the world, our results can be important to better understand the past and envisage several future scenarios. Discussion of potential AMO shift back in 2013. https://tropical.colostate.edu/Publications/sidebars/fogarty_and_klotzbach_2014.pdf

This is a great explainer on why we only had 5 named storms so far and models like the Euro were forecasting over 20 for the season. But as we saw with Beryl, individual systems that are able to form with the record SSTs can become very intense. Many have been commenting in this unusual AEW behavior so far this season especially for a La Niña with record Atlantic SSTs. https://news.ucar.edu/132966/dampening-seeds-hurricanes

Another top 5 warmest summer for many stations across the Northeast.

The exception to that was 09-10 to 17-18 with the very high concentration of BM snowstorms. Starting in 18-19 we shifted to more of a coastal hugger, cutter, and suppressed southern stream pattern. While all the winters going back to 15-16 were warmer to record warm in the Northeast, we still had a very favorable Pacific through the November 2018 snowstorm. Then we entered the very hostile Pacific phase that winter. People were willing to overlook all the warmth from 15-16 to 17-18 since the benchmark put on a real show for snow lovers. But warmth and a hostile Pacific won’t cut it around here for good winters. 20-21 really went against the grain for one the strongest +PNA patterns for such a robust La Niña. Seems like a piece of that repeated briefly in January 22. Since then it really has been pretty much a shout out for winter. Hoping we can at least see some snowfall improvement over the last two winters even though the early signals are there for a potential 10th warmer than normal winter in a row for the Northeast.

It remains to be seen since there is such a small sample size of inactive years between 8-20 and 8-31 during La Ninas.