bluewave

Steadily rising September temperatures brought the recent 10 year period to a 70.3° average in NYC. September has shown the fastest monthly temperature rise for much of the East. So expect a significant monthly average temperature increase when the new 30 year climate normals come out. Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Sep Season Mean 70.3 70.3 2020 68.8 68.8 2019 70.4 70.4 2018 70.7 70.7 2017 70.5 70.5 2016 71.8 71.8 2015 74.5 74.5 2014 69.7 69.7 2013 67.9 67.9 2012 68.8 68.8 2011 70.0 70.0 Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Sep Season Mean 69.2 69.2 2010 71.1 71.1 2009 66.3 66.3 2008 68.8 68.8 2007 70.3 70.3 2006 66.6 66.6 2005 73.3 73.3 2004 69.3 69.3 2003 67.9 67.9 2002 70.2 70.2 2001 67.7 67.7 Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Sep Season Mean 67.8 67.8 2000 66.0 66.0 1999 69.0 69.0 1998 70.2 70.2 1997 67.0 67.0 1996 68.0 68.0 1995 68.3 68.3 1994 67.6 67.6 1993 67.3 67.3 1992 67.2 67.2 1991 67.5 67.5

Heaviest rains in the interior and strongest measured winds along the coast. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSOKX&e=202009301439 ...Rockland County... Sloatsburg 3.88 815 AM 9/30 CWOP Suffolk County... West Gilgo Beach 64 445 AM 9/30 CWOP

Updated for the 3.88 in Sloatsburg, NY. Rockland County... Sloatsburg 3.88 815 AM 9/30 CWOP

Record 7th consecutive September above 70° at LGA. The NYC and EWR version of this is 7 consecutive years above 68°. Monthly Mean Avg Temperature for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Sep Season 2020 71.2 71.2 2019 72.1 72.1 2018 72.8 72.8 2017 71.5 71.5 2016 73.8 73.8 2015 74.1 74.1 2014 70.4 70.4 2013 68.1 68.1 Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Sep Season 2020 68.9 68.9 2019 70.4 70.4 2018 70.7 70.7 2017 70.5 70.5 2016 71.8 71.8 2015 74.5 74.5 2014 69.7 69.7 2013 67.9 67.9 Monthly Mean Avg Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Sep Season 2020 69.2 69.2 2019 70.8 70.8 2018 71.4 71.4 2017 70.9 70.9 2016 71.8 71.8 2015 73.4 73.4 2014 69.8 69.8 2013 67.2 67.2

https://www.nature.com/articles/d41586-018-05978-1 Ocean heatwaves will become more frequent and extreme as the climate warms, scientists report1 on 15 August in Nature. These episodes of intense heat could disrupt marine food webs and reshape biodiversity in the world’s oceans. Scientists analysed satellite-based measurements of sea surface temperature from 1982 to 2016 and found that the frequency of marine heatwaves had doubled. These extreme heat events in the ocean's surface waters can last from days to months and can occur across thousands of kilometres. If average global temperatures increase to 3.5 °C above pre-industrial levels by the end of the century, as researchers currently project, the frequency of ocean heatwaves could increase by a factor of 41. In other words, a 1-in-100-day event at pre-industrial levels of warming could become a 1-in-3-day event. Marine heatwaves have already become more long-lasting, frequent, intense and extensive than in the past,” says lead study author Thomas Frölicher, a climatologist at the University of Bern in Switzerland. He adds that these changes are already well outside what could be expected on the basis of natural swings in Earth’s climate: the study’s analysis determined that 87% of heatwaves in the ocean are the result of human-induced global warming. Going global Scientists have studied heatwaves on land for decades. But it wasn’t until researchers faced episodes of extreme heat in the ocean in the past several years that they started paying more attention to the issue at sea. Those episodes included the massive warm water ‘blob’ in the northeastern Pacific Ocean that killed off sea otters (Enhydra lutris) in Alaska and sea lions (Zalophus californianus) in California, and disrupted fisheries off North America from 2014 to 2015. They also included the massive 2015–16 El Niño that ravaged coral reefs around the world. The emphasis on marine heatwaves is really motivated by the recognition that the same kinds of extremes can happen in the ocean as on land,” says Noah Diffenbaugh, a climatologist at Stanford University in California. He adds that this latest study takes global perspective on these regional issues. The study provides a useful framework for disentangling short-term temperature spikes from long-term warming trends in the oceans, says Kris Karnauskas, a physical oceanographer at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. He says that marine heatwaves could be the result of natural temperature swings that become more extreme owing to a warming ocean. Or they could be a signal that global warming is changing how the ocean functions — thus altering the likelihood and intensity of marine warming events. Frölicher says current models suggest that more frequent and intense ocean heatwaves are largely a result of warming oceans. And now, he and his team are working to develop models that can explore marine heatwave trends and their ecological impacts at local and regional levels. https://www.nature.com/articles/s41586-018-0383-9 https://www.nature.com/articles/s41467-019-08471-z#ref-CR7 Tropical cyclones that rapidly intensify are typically associated with the highest forecast errors and cause a disproportionate amount of human and financial losses. Therefore, it is crucial to understand if, and why, there are observed upward trends in tropical cyclone intensification rates. Here, we utilize two observational datasets to calculate 24-hour wind speed changes over the period 1982–2009. We compare the observed trends to natural variability in bias-corrected, high-resolution, global coupled model experiments that accurately simulate the climatological distribution of tropical cyclone intensification. Both observed datasets show significant increases in tropical cyclone intensification rates in the Atlantic basin that are highly unusual compared to model-based estimates of internal climate variations. Our results suggest a detectable increase of Atlantic intensification rates with a positive contribution from anthropogenic forcing and reveal a need for more reliable data before detecting a robust trend at the global scale.

The Central Arctic continues to set records for low extent as we get close to the beginning of October.

64th day this year at JFK with a 70° or higher dew point. This brings JFK into 4th place. The top 4 years were all since 2016. Kennedy Intl LGT RAIN 72 70

Looking like our first year with 30 or more 90° days and none in the spring or fall. Monthly Number of Days Max Temperature >= 90 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 2010 0 0 0 1 2 12 18 11 4 0 0 0 48 2018 0 0 0 0 4 4 10 16 4 0 0 0 38 2002 0 0 0 2 0 5 14 13 1 0 0 0 35 2020 0 0 0 0 0 5 19 10 0 M M M 34 1991 0 0 0 0 4 9 10 9 2 0 0 0 34 2016 0 0 0 0 3 1 15 10 3 0 0 0 32 1983 0 0 0 0 0 5 11 8 7 0 0 0 31 2005 0 0 0 0 0 7 10 10 3 0 0 0 30 1953 0 0 0 0 1 7 10 9 3 0 0 0 30

Within the last few days. Looks like it’s part of their big upgrade. https://eccc-msc.github.io/open-data/msc-data/changelog_multisystems_en/#tuesday-january-21-2020 A major project to migrate to a new supercomputing infrastructure employed by the Meteorological Service of Canada was completed on January 21, 2020. This successful migration was the result of a joint, sustained effort over several months by experts at the Canadian Meteorological Centre, Science and Technology Directorate, and Shared Services Canada. Over the coming years, this important upgrade will permit further technological transfers from Research and Development into Operations, supporting the continuous improvement of the meteorological and environmental forecast services offered to Canadians and to other federal and provincial government agencies, users, and partners. The official note announcing the migration is available at this lin

Another example of these abrupt precipitation shifts that many areas are experiencing. Very challenging time to be in the agricultural industry. We can swing from one extreme to another.

Very unusual rainfall distribution this month. Portions of Long Island experienced one of their wettest starts to September. This was followed by record dry conditions since then. Heavy rains to end the month will only add to the oddity. 9-10....Pt Lookout....6.47.....Massapequa....5.41...Wantagh Mesonet...4.64....Amityville....4.04....Copaigue....4.05 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Precipitation Sep 11 to Sep 26 Missing Count 1 1910-09-26 0.00 0 - 1908-09-26 0.00 0 - 1884-09-26 0.00 0 2 2020-09-26 T 0 - 1941-09-26 T 0 - 1917-09-26 T 0

Hartford is hoping for their first 1”+ rain event since late April.

Cool departures should turn warm as we continue the warmer September pattern.

This was their driest ever 05-01 to 9-25. Time Series Summary for Hartford Area, CT (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Precipitation May 1 to Sep 25 Missing Count 1 2020-09-25 6.98 0 2 1964-09-25 8.35 0 3 1957-09-25 8.82 0 4 1965-09-25 9.45 0 5 1914-09-25 10.79 0

Maybe the wetter Euro and UKMET further east will work out for them. I guess it comes down to how much of a phase we get between the two pieces of energy.

The New England crew is probably happy that this is a rainfall departure and not snowfall.

We are on track to set a new September monthly 500 mb positive height record for the West Coast. A new daily record was set earlier this month. This would surpass the previous September monthly record set in 2012.

https://www.disl.edu/about/news/marine-heatwaves-and-hurricanes-study-examines-compounding-impact-of-severe-weather Several coastal communities are picking up the pieces after being ravaged by hurricanes in the past month. Hurricane Laura, a category 4, and Hurricane Sally, a category 2, seemed to meander their way across the Gulf of Mexico constantly shifting forecasts and keeping meteorologists on their toes. In the hours before these storms struck land, they seemed to explode in intensity. Researchers at the Dauphin Island Sea Lab with support from the Jet Propulsion Laboratory can offer insight into why these storms intensified quickly as they moved across the continental shelf. “Surprisingly, both Hurricane Laura and Hurricane Sally appeared to have similar setups to Hurricane Michael with both storm events being preceded by smaller storms (i.e. Hurricane Hanna and Marco, respectively),” Dr. Brian Dzwonkowski explained. “This pre-storm setup of the oceanic environment likely contributed to the intensification prior to landfall. Importantly, this pre-landfall intensification was not well predicted by hurricane models or forecasts, which as you can imagine is critical information for evacuation and disaster preparation.” Dzwonkowski and his team’s publication, “Compounding impact of severe weather events fuels marine heatwave in the coastal ocean”, outlines how one storm could impact the intensity of another storm by restructuring the thermal properties of the water column. Nature Communications published the findings in its September issue. The research focuses on Hurricane Michael which devastated Mexico Beach, Florida, and the surrounding communities, on October 10, 2018. The category 5 storm intensified hours before making landfall. Dzwonkowski, a physical oceanographer with the Dauphin Island Sea Lab and Associate Professor at the University of South Alabama in the Department of Marine Sciences, and his team tracked down the key events and processes that pushed the coastal waters in the Gulf of Mexico to an extremely warm state (i.e. a marine heatwave), likely contributing to the intensification of a storm so close to shore. Unlike the deep ocean, the continental shelf has a shallow bottom that limits how much cold water can be mixed up to the surface, cooling the sea surface temperature and weakening approaching storms. Dzwonkowski and his team focused on how a strong mixing event pushes surface heat downward and clears the bottom water of its cold water reserve. If this mixing is followed by a period of rewarming, such as an atmospheric heatwave, the shelf’s oceanic environment could be primed for the potential generation of extreme storm events, i.e. Hurricane Michael. This work shows that understanding the preceding weather conditions in a region where a storm is going to make landfall can improve interpretation of hurricane model forecasts and what the storm is likely to do prior to landfall,” says Dr. Dzwonkowski In mapping out heat flux and mixing, the team focused on the Mississippi Bight in late summer and early fall with data gathered by a mooring site off Dauphin Island’s coastline. The mooring site collects data throughout the water column allowing for the full heat content of the shelf to be determined. The period prior to the landfall of Hurricane Michael turned out to be the warmest ocean conditions during this time period in the 13-year record. “Turns out hurricanes and atmospheric heatwaves will be getting stronger in a warming world which would indicate the identified sequence of events that generate these extreme conditions may become more frequent,” Dzwonkowski said. “The occurrence of extreme heat content events, like marine heatwaves has significant implications for a broad range of scientific management interests beyond hurricane intensity.”Importantly, the mechanisms that generated this marine heatwave are expected to be more frequent and intense in the future due to climate change, increasing the likelihood of such extreme conditions. For example, coral reefs and hypoxia-prone shelves are already stressed by long-term warming trends. These temperature-specific benthic communities and habitats are typically of significant societal and economic value. As such, the newly identified sequence of compounding processes is expected to impact a range of coastal interests and should be considered in management and disaster response decisions. This research was funded by the NOAA RESTORE Science Program and NOAA NGI NMFS Regional Collaboration network. https://www.nature.com/articles/s41467-020-18339-2 Abstract Exposure to extreme events is a major concern in coastal regions where growing human populations and stressed natural ecosystems are at significant risk to such phenomena. However, the complex sequence of processes that transform an event from notable to extreme can be challenging to identify and hence, limit forecast abilities. Here, we show an extreme heat content event (i.e., a marine heatwave) in coastal waters of the northern Gulf of Mexico resulted from compounding effects of a tropical storm followed by an atmospheric heatwave. This newly identified process of generating extreme ocean temperatures occurred prior to landfall of Hurricane Michael during October of 2018 and, as critical contributor to storm intensity, likely contributed to the subsequent extreme hurricane. This pattern of compounding processes will also exacerbate other environmental problems in temperature-sensitive ecosystems (e.g., coral bleaching, hypoxia) and is expected to have expanding impacts under global warming predictions.

Montana was one of the few spots not to see as many above normal months.

Yeah, I saw that. The early 90s were colder times combined with the strong +AO and PV. We actually surpassed those records last JFM. A new paper mentions that the IO standing wave may have contributed. Similar to another paper that I posted last winter. So we need to look to the Indian Ocean for hints on the AO. So some of the long range +AO forecasts for last winter worked out very well. But it verified much stronger than they indicated. https://www.essoar.org/pdfjs/10.1002/essoar.10503356.1 P Positive SST anomalies in the Indian Ocean have

Maybe another 70° minimum if the front slows down enough.

Looks to max out from 4 to 5 sd around Alaska and also Greenland.

Expansion of the extreme drought conditions in New England.