A new forecast for Summer 2021 (least for June and July 2021) was updated on AER Blog /https://www.aer.com/science-research/climate-weather/arctic-oscillation//.
The most interesting published outputs on the blog and Twitter were forecasts for 4-33 and 34-64 day or June 2021 and July 2021 for Northern Hemisphere.
From the outputs is evident, that Europe, mainly including Mediterranean (latest ECMWF forecasts promised warm southern Europe least: https://mkweather.com/summer-2021-in-europe-will-be-colder-such-was-forecasted/), similarly such as colder Midwest in the USA and in July cold East Asia, will be experiencing with not a very hot Summer 2021.
Canadian Arctic and Verkhoyansk region, such as Sahara, Middle East and later again Central Asia and European Russia and western Siberia, should thanks to blocking situation above Europe profit by tropical advections with origin in the Middle East and Sahara.
According to AER "The latest CFS forecast for July shows a surprisingly lack of heat across the Northern Hemisphere", what means, that large parts of continents, mainly the USA, southern Canada, Europe or Eastern Asia or parts of non-Arctic Russia.
However, circulation like this should trigger extreme heatwaves in desert climate from Sahara, trough Middle East to Gobi desert, while Sahel and subequatorial climate zone should be colder and stormy.
Cold pattern for Europe should mean more showers and more cold outbreaks from N-NW into Europe, probably near predominant AO- / NAO- phases, weaker Icelandic low and Azores high and stronger Greenland high.
Circulation pattern from last months (La nina, solar cycle minimum, above average volcanic activity) /https://mkweather.com/a-big-european-circulation-anomaly-in-2021-totally-oppositely-such-as-in-the-world-and-showing-what-climate-change-should-bring-until-2100/; https://mkweather.com/2021-22-little-ice-age-years-with-volcanic-activity-in-last-30-years-had-tendency-to-be-la-nina-during-solar-cycle-minimum/; https://mkweather.com/2021-22-little-ice-age-years-with-volcanic-activity-in-last-30-years-had-tendency-to-be-la-nina-during-solar-cycle-minimum/; https://mkweather.com/the-next-cold-winter-strong-la-nina-in-winter-2021-2022-forecasted/; https://mkweather.com/solar-cycle-behind-nao-coldwaves-in-europe-and-la-nina-coldwaves-around-the-world-2021// therefore should be in main features preserved in Summer 2021, what should bring in European countries many surprises.
In some region of Europe, cold summer, with negative temperature anomaly below 0°C hasn´t been measured more than 30 years and there is a not negligible possibility, that Summer 2021 should break this long line, similarly, such as Spring 2021 should end in parts of Europe such as the coldest since 1987 https://mkweather.com/the-coldest-spring-2021-in-europe-since-1987//.