Global Soil Moisture Anomalies And 3-Month Trend

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The most striking soil moisture anomalies across the globe as of Nov. 1, 2019 is the historic wet signature across India (afte rthe latest wet monsoon on record) and drought signatures ove rparts of Brazi, Europe, South Africa and Australia.

Fig. 1: The 3-month global soil moisture change chart.

Discussion: Two areas are vividly dry (Brazil) and wet (India). The 3-month trend in Brazil is much drier with the core of the dry change in southwest and southeast Brazil (Fig. 1). The dryness extends to central Brazil. Central Argentina also trends drier the past 3 months. The primary contributor to the South America dryness is cooler than normal SSTA in key moisture source regions off the west coast of South America and east of Brazil. Waters southeast of Brazil have warmed in recent weeks. The historic wet regime across India caused by the latest wet monsoon on record was caused by the influence of a historic positive phase of the Indian Ocean Dipole (+IOD) which continues.

In the U.S. the already soaking wet northern Great Plains trend wetter during the past 3 months. The culprit is a semi-permanent upper low pressure trough over the Interior Northwest U.S. present all of 2019 and the catalyst to the Great Plains wet pattern this year. To the south of this very wet zone the Southwest U.S. into northern Mexico is much drier. Additionally, Florida to Cuba to Central America trended drier the past 3 months.

There are no major soil moisture changes in Europe as dryness is dominant. Southeast Europe to Ukraine trended drier during the past 3 months beneath a semi-permanent upper level high pressure system. The persistent upper level trough across the cool pool of water south of Greenland known as the North Atlantic Warm Hole (NAWH) emitted low pressure troughs across U.K. causing a wet soil moisture change. Wind flow off the Norwegian Sea caused Northwest Russia to turn wetter than normal.

The South Africa drought widened and intensified while east Africa tropical areas trended wetter due to the influence of the +IOD regime. Eastern tropical Africa also trended wetter the past 3 months.

The East China and Australian drought worsened during the past 3 months.

The 30-day global SSTA analysis and trend (Fig. 2) indicates neutral ENSO although the anomalous warmth near the Dateline recently spread eastward. Close monitoring of this eastward warm expansion is watched closely as the subsurface in this region is very warm. Dynamic/statistical models are not forecasting the return of El Nino. However, a weak El Nino surprise is certainly possible. The strong positive IOD pattern continues but is forecast to weaken by early 2020. The NAWH pattern in the North Atlantic is unusually strong for this time of year and forecast to continue through upcoming winter and certainly influencing the winter 2019-20 climate across Europe. Similarly, a “warm blob” in the northern Pacific Ocean persists and will influence the northwest North America climate during the winter season.

Fig. 2: The global 30-day SSTA trend analysis.