Pictured: NOAA percentile ranking of global soil moisture and annotated 3-month trend.
During the past 3 months regional soil moisture changes include a drier trend across vast portions of North and South America while Central America to the eastern U.S. were wetter. Wetter changes were notable in Western Russia, western tropical Africa, eastern Saudi Arabia and western India. East-Central Russia to northern China were much drier the past 3 months similar to Australia where drought is intensifying. Dryness was also dominant across Interior Southeast Asia plus the western portion of Indonesia.
The dryness across the western U.S. and southwest Canada is due to a persistent upper ridge pattern returning after an exceptional wet last winter. The long-term drought wiped out by last winter’s rainfall has re-emerged. Vast dryness also affects eastern Canada due to a dry land wind in that region. A persistent upper trough over the Great Lakes lead to a wetter soil moisture trend in the east and southeast portion of the U.S.
A cool pool of water across the north-central North Atlantic correlates to a persistent upper trough in that same region. East of the upper trough a well-amplified upper ridge causes a harsh drought in southern Europe. Farther upstream a dominant upper trough in north-central Russia causes a vast wet soil moisture regime for that region although Ukraine has been somewhat drier.
While west/west-central Russia turned wetter the past 3 months the east-central portion of Russia to northeast China trended much drier. The dryness has generally included the Korean Peninsula. A large area of high pressure has dominated southern Russia, Mongolia and northern China the past 3 months. Southeast Asia has been mixed while dryness is strengthening across Western Indonesia.
The Indian Monsoon has varied in intensity and duration mostly linked to the Madden Julian oscillation regime. Western India has observed much wetter conditions.
A widening drought is occurring in Australia largely due to the cool SSTA pattern west and southwest of Australia lowering available moisture transported across Australia by the prevailing storm track.
In South America dryness has been widespread. While central and southeast Argentina maintain a wet signature far northeast Argentina to southeast Brazil trended drier. Western Brazil dryness has developed leaving most of Brazil in a drought.
