bluewave

A simplified way to think of extent versus area is to imagine a slice of swiss cheese. Extent would be a measure of the edges of the slice of cheese and all of the space inside it. Area would be the measure of where there is cheese only, not including the holes. Frequently Asked Questions on Arctic sea ice The block back in June set the all-time record for the highest 500mb heights over that section of the Russian Arctic for the month of June.

Looks like the daily area has actually dropped below 2012. Probably the biggest spread we have seen between area and extent in mid-August. So that dipole pattern back in June must have a very big influence. https://sites.google.com/view/arctic-sea-ice/home/about

Looks like the thickest smoke of the season so far.

Ben Noll has it on his site. Just open the menu and scroll down. https://www.bennollweather.com/climate-graphics

Yeah, seasonal forecasts like the Euro just rely on SST and La Niña. They don’t forecast dust very well which is an inhibiting factor. But the dust usually relaxes in a September which could allow things to ramp up in September with the record SSTs and La Niña as we approach the peak of the hurricane season.

This will be the first time that such a strong El Niño had this much more tropical development in late August than a La Niña the following season. We were already up to the K storm by the end of August last year. So my guess is that the competing marine heatwaves around the world are altering the typical tropical activity response in recent years. But most years don’t show the peak in activity until September which is still ahead of us. September is when the dust usually relaxes.

Probably have to rely on convection for rains next few weeks as the tropics look quieter after Ernesto. We’ll see if one of the waves can enhance the rainfall or maybe try to develop as we get closer to September.

First time since 1955 that August opened with a 100° first week followed by a tropical storm which broke the heat.

95° has been the average max last decade after August 25th at Newark. But it’s been a challenge since 1993 reaching 100°. Must be related the summers getting wetter. Had the 2019 early October flash drought been a month earlier we would have done it. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2023-10-07 97 0 2022-10-07 93 0 2021-10-07 97 0 2020-10-07 93 0 2019-10-07 96 0 2018-10-07 98 0 2017-10-07 92 0 2016-10-07 95 0 2015-10-07 98 0 2014-10-07 95 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 1953-10-07 105 0 2 1948-10-07 103 0 3 1993-10-07 100 0 - 1973-10-07 100 0

Could be a few more scattered cold pool storms later. The warm spots in NJ may make a run on 90° Friday. Then scattered storms over the weekend into early next week as an upper low and frontal system slows down coming east.

A new study on reduced shipping aerosols potentially contributing to the global temperature rise over the last year or so. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024GL109077 5 Synthesis and Conclusions New methods are making rapid progress in identifying ship tracks with machine learning, and using trajectory methods and satellite imagery to understand the evolution of cloud properties over time for both visible and invisible tracks. These methods indicate significant reductions in visible ship tracks since the IMO2020 shipping regulations changes reduced sulfur emissions from ships. Global estimates are 25%–50% reduction in the number of visible tracks. This work should help us better constrain at the process level the impact of visible and “invisible” ship emissions on marine clouds and extend that globally. Simulations with hybrid approaches and global models indicate a radiative forcing change of +0.12 ± 0.03 Wm−2 could result from the reductions in sulfur emissions. This result is based on simulations from several models. However, further refinement of models is still desired. For example, simulations reduce shipping sulfur mass emissions, but the IMO2020 sulfur regulation has had a drastic effect on the size distribution and number of primary aerosols from shipping (Yu et al., 2020), affecting aerosol number and possibly radiative forcing. There has been speculation that the record warm temperatures in 2023 are at least partially attributable to the reduction of cooling as a result of the IMO2020 regulations. The analysis of recent temperatures shows that the anomalies in temperature in 2022 and 2023 were correlated (in space) with changes in clouds. Since 2020 the correlation between temperature and clouds has been above 0.4, higher than over any 3 year period in the CERES record back to 2002. The magnitude of the observed cloud changes is too large to only be a cloud feedback response to temperature changes, implying that other factors have been modifying clouds. Further simulations analyzing cloud anomalies with and without surface temperature anomalies could be used to try to quantify the feedback contribution. Furthermore, there are significant (but weak) pattern correlations with simulations of cloud changes due to shipping emissions. The magnitude of the observed CRE anomalies is about 3X larger than would be expected from shipping emissions alone. On a global or Northern Hemisphere average, the CERES observed CRE is not anomalous over the 2020–2023 record, so no large scale shift in clouds is evident due to meteorology. This analysis indicates it is plausible that the IMO2020 shipping regulations changes through sulfur emission reduction have significantly contributed to recent Northern Hemisphere temperature anomalies. Shipping cannot account for all of the observed warming. The analysis is done using 2 years of data data under the new shipping emissions, and only one set of model simulations is used for pattern correlations. However, the results are not that sensitive to the exact surface temperature data or dates used for the correlations, and the forcing is similar across models, and not dependent on the specific nudging period. Pattern correlations are significant but weak, and more detailed process analysis is needed. Attribution with an energy balance model indicates that the global average contribution of shipping changes could be nearly 20% of expected warming by 2023. Energy balance modeling also indicates that perhaps half the total global warming of ∼0.07 K from the shipping emissions effects of +0.12 W m−2 has been realized after four years (2020–2024), and continued warming is expected. The forcing is however highly localized. Based on the patterns of warming, a substantial part of 2023 warming over the N. Hemisphere mid-latitude oceans could be attributed to shipping emissions reductions. To constrain the attribution, further simulations with constrained coupled model simulations with an interactive ocean would likely be needed. However, this will not be trivial: the global shipping perturbation of +0.1 Wm−2 and about 0.07 K of temperature rise would have to be discerned from coupled simulations with climate noise. As an example, the interannual standard deviation of 101 years (years 1100–1200) of the CESM2 pre-industrial control simulation (Danabasoglu et al., 2020) is 0.47 Wm−2 for net TOA flux and 0.09 K for SST. Thus large ensembles, long runs and/or careful constraints would be required. The IMO2020 regulations are a critical “natural laboratory” to determine whether continued declines in general air pollution due to regulations around the world will continue to increase and possibly accelerate global warming over the next decades (Hansen et al., 2023). This is critical for reducing the large uncertainty in climate forcing due to aerosols (Bellouin et al., 2020), and for evaluating the potential of intentional modification of marine clouds to offset global warming (Diamond et al., 2022). To better constrain these results further at the process level, we need better access to ship position and type information from the Automatic Identification System (AIS), which broadcasts ship position and identification information. Almost all the AIS data (especially satellite derived open ocean data), even historical, is only available at a prohibitive cost. Releasing such data for research would allow detailed identification of specific ships with tracks, enabling extension of work by Gryspeerdt, Goren, et al. (2019) and Manshausen et al. (2022, 2023) to be conducted statistically and globally. This would enable us to directly link emissions to cloud perturbations and better constrain how much the IMO2020 regulations, and air pollution control in general, will contribute to global warming over the next decade. The IMO2020 regulations can be seen as an inadvertent experiment in solar geo-engineering, but in reverse (warming). Ship sulfur reductions may have contributed a significant amount to the 2023 extreme temperatures in the Northern Hemisphere, but the estimated magnitude appears to be too small to be the only cause. The significant ENSO warm event in late 2023 would have played a role as well. Understanding and attributing the changes is not just relevant for ships and the current decade, but for several decades to come as the world rapidly decarbonizes and reduces all anthropogenic emissions of sulfur and other particulates. To what extent are we accelerating climate change by cleaning up air quality faster than limiting greenhouse gas emissions? Our inability to provide a robust attribution of global radiative forcing and resulting temperature changes even 3 years after such a large experiment speaks to the huge challenges in managing any deliberate intervention (Diamond et al., 2022) due to natural variability.

Could be some cold pool convection dropping down from the north later.

Looks like we warm up days 11-15 as the WAR flexes. Probably start to see at least some more low 90s. If the WAR links up with ridge to our West than mid 90s will be possible.

We have seen this several times since 2012 when a shorter period with a strong dipole caused a steep drop. In order to surpass 2012 we need a more sustained dipole pattern on top of early season preconditioning. The early August extreme drop in 2012 hasn’t been able to be surpassed yet as we have seen again this year. What may eventually happen is that the steadily warming Arctic could eventually allow 2012 to be surpassed with shorter dipole pattern like we had this summer. But the Arctic hasn’t warmed to that point yet. But it will be interesting to see how things go in coming years. There was a recent new paper explaining why 2012 has been so tough to replicate. https://www.climate.gov/news-features/understanding-climate/five-things-understand-about-ice-free-arctic Over the course of the entire satellite record, the average rate of Arctic sea ice loss is striking. If one looks at separate parts of the satellite record, different rates of ice loss emerge. Walter Meier has examined these different rates. He says, “From about 2002 to 2012, we had a pretty rapid decline in extent. September extents set new record lows in 2002, 2005, 2007, and 2012. But since 2007, the trend is essentially zero.” Meier cautions that this doesn’t imply any kind of Arctic sea ice recovery, only that 2012 remains the record holder. Greenhouse-gas emissions have continued to climb, so it’s possible that additional factors are at play. Dániel Topál suspects the principal other factor is natural variability. He doesn’t dispute the relationships between greenhouse-gas emissions, temperature, and sea ice, but he concludes natural variability will affect the timing of an ice-free Arctic to a greater degree than some other researchers have recognized. “Our paper says that models underestimate the atmospheric forcing influence, which is partially externally driven and partially internally driven,” he explains. catch, Topál explains, is that internal atmospheric variability has a bigger influence on Arctic temperatures than it has on global temperatures. He says, “In reanalyses, Arctic surface temperature trends are influenced by atmospheric circulation at least about 30 percent, but this effect seems to be missing in the models.” Topál suspects that ocean surface temperature variability as far away as the tropics could affect Arctic sea ice. “That’s probably what’s missing in the models right now. We still don't understand very much about it because our satellite observations are just nearly 50 years long and some of the oscillations in the Pacific can be up to 30 years,” he says. Even lacking certainty about Pacific oscillations, Topál can highlight natural variability in the Arctic climate, such as the Arctic Oscillation, that affects sea ice. “Atmospheric circulation between 2000 and 2012 was especially in favor of the anticyclonic circulation that increased the chances of rapid ice loss. Since 2013, we've seen a different circulation regime in the Arctic.” The record-low September 2012 Arctic sea ice minimum is a perfect example of the combination of long-term warming and weather. The minimum that summer was so far below the previous record that it appeared to foretell a grim future for the Arctic; it seemed possible that summer sea ice might decline to nearly nothing perhaps in a matter of years rather than decades. Since 2012, however, Arctic sea ice has not continued a significant decline. Although the September 2020 minimum came within roughly 430,000 square kilometers (170,000 square miles) of the record low, the 2012 record has not yet been matched. Obviously, 2012 being below average had a lot to do with the long-term trend. But the fact that it was record-low was due to the weather. Not only did Arctic atmospheric circulation favor sea ice decline in 2012, but there was another contributing factor. The National Snow and Ice Data Center (NSIDC) reported a strong storm centered over the Arctic in August of that year. The storm broke up the Arctic’s sea ice, driving down its extent, although the precise impact of this individual storm remains unclear. Storms are nothing new in the Arctic Ocean, but their influence on sea ice has grown over time. Dániel Topál says, “Weather events and storms definitely play a huge role. Sea ice is getting younger and younger, thinner and thinner.” Arctic sea ice is thinning because less ice survives summer melt seasons. Whereas ice that has survived multiple melt seasons is thick, rough, and resistant to melt, younger ice is vulnerable to storm-induced breakups. The same storm, encountering thicker ice, would likely have had less impact. “I think with the thinner, younger ice that’s in the Arctic now, there is the potential for even more sea ice variability,” Walter Meier says. Several years of [weather] conditions that favor ice growth, or at least ice preservation, would slow the arrival of an ice-free Arctic summer; a few years of extreme melt conditions or a few strong storms could hasten the arrival of ice-free conditions. But, Meier explains, weather conditions can’t be predicted more than about 10 days into the future. Furthermore, scientists don’t have a handle on potential changes in weather systems, such as Arctic storm intensity, that may emerge in coming decades.

The most recent version of that was Henri and Ida record flooding from late August into early September 2021.

6-17 to 08-06 was the warmest on record for Central NJ. Time Series Summary for New Brunswick Area, NJ (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 2024-08-06 79.2 0 2 2010-08-06 78.5 0 3 1955-08-06 78.2 0 4 2020-08-06 77.7 0 - 2006-08-06 77.7 0 5 1949-08-06 77.5 0 Time Series Summary for SOMERSET AIRPORT, NJ Click column heading to sort ascending, click again to sort descending. 1 2024-08-06 78.2 0 2 2020-08-06 76.7 0 3 2006-08-06 76.4 0 4 2019-08-06 76.1 0 5 2010-08-06 76.0 0 Time Series Summary for HIGHTSTOWN 2 W, NJ Click column heading to sort ascending, click again to sort descending. 1 2024-08-06 79.2 0 2 2010-08-06 78.2 2 3 1955-08-06 77.7 0 4 1894-08-06 77.4 2 5 1934-08-06 77.2 35

Yeah, we always get these photogenic cloud structures when a cold pool is moving overhead.

While the Northeast has had a record breaking 9 consecutive warmer to record warm winters since 15-16, we still haven’t had a departure yet rivaling the magnitude of 2001-2002 or 1931-1932. Those were the 2 most anomalous warm departure winters relative to their 30 year averages. So at least we haven’t had a winter since 15-16 with a departure over +7.0 yet. As the winters continue to warm so do the 30 year averages. If we ever got a repeat of 01-02 or 31-32 departures in this much warmer climate, then it would be the first winter in the Northeast to average above freezing. I used dense rank sorting for the top 10 warmest Northeast winters by temperature rankings below. #1…..2023-2024…..31.3°……+5.5 #2….2001-2002…..31.2°…….+7.1 #3….2022-2023…..30.7°……+4.9 ……..2015-2016……30.7°…….+5.8 #4….2011-2012……30.0°……..+5.9 #5…..1997-1998…..29.6°……..+6.8 #6…..2016-2017…..29.5°……..+4.6 ………1931-1932……29.5°……..+7.4 #7…..2019-2020…..28.9°……..+4.0 #8…..1932-1933…..28.4°………+6.3 #9…..1998-1999……28.2°……..+5.4 ……….1948-1949…..28.2°………+5.3 #10….1952-1953……28.1°………..+4.8 https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/regional/time-series/101/tavg/3/2/1895-2024?base_prd=true&begbaseyear=1901&endbaseyear=2000

Pop up convection with the trough swinging through.

It’s a real rarity these days to get a cooler and drier 5 day period. Most of our cooler periods have been due to heavy rains in the warm season. So looks like a great week of weather for outdoor activities coming up.

Plenty of sinking air forecast day 11-15 in the Atlantic basin so there may be a break in activity after Ernesto for a time.

We will be in a recurving TC pattern for a while as the trough axis is right along the East Coast. This is actually the weakest the WAR has been all summer. So not much in the way of heat with a pattern like this.

Where was this pattern last winter?

Record rains in Montreal this month following the wettest month on record in July for Toronto.