Global Soil Moisture Trend & Outlook

Introducing Atmospheric River Index
02/06/2019, 2:38 pm EDT
Strongest –PNA on record beneath a historic cold polar vortex causes record West U.S. cold in February. Related to solar minima?
02/10/2019, 10:32 am EDT
Show all

The most dramatic soil moisture changes the past 3 months are wetter across the eastern half of the U.S., drier in Brazil and South Africa.

Past 3 months: Much wetter eastern half of U.S.; Suddenly much drier Brazil.

Next 3 months: Wet Great Plains, some relief for southern Brazil.


Fig. 1: January 2019 global soil moisture % of normal and 3-month trend.

Observation discussion: The most striking soil moisture signatures after January 2019 remain the potent dryness in Europe present since last summer and worsening in recent months in northern Europe AND the steadily evolving wet soil moisture regime of the eastern 2/3 of the U.S. Sharp contrast is evident in many regions as almost all of the southern 1/2 to 2/3 of Canada is very dry while to the south the U.S. is wet and trending wetter. Another rapidly evolving and contrasting soil moisture region during January is the dryness across Brazil matched with very wet conditions in Uruguay to northeast Argentina.

In the Black Sea region previously dry conditions has eased slightly in early 2019 from Turkey to Ukraine and into gar southwestern Russia while dryness to the east of this region remains intense. Central Russia wet soils and northeast Russia dry soils strengthened slightly during January. Remarkably, there is not much change during the past 3 months to Eastern Asia except drier far Southeast Asia and wetter near the coast of China.

Slightly wetter in Indonesia during the last 3 months while the Australian drought remains intact and steady through the last 3 months. In Africa drought is intensifying for southern sections and more recently West Africa to the south of the equator.

Forecast discussion: The 3-month outlook is somewhat contingent on the ENSO regime. Currently, ENSO is in neutral phase. However, gathering surface and subsurface warmth near the Dateline is impressive and typically warmth in this zone shifts east into the East Pacific and can cause El Nino to develop. Therefore there is risk of El Nino returning during northern hemisphere spring. The climate forecast is driven by a neutral ENSO to weak El Nino climate correlation.

No major changes to the North America soil moisture regime are expected. Only 2 prominent soil moisture change forecasts are indicated. A wet scenario trends already wet soils wetter in the central, south and southwest Great Plains while a short distance to the east trends drier in the Missouri Valley to Illinois.

The Europe drought regains strength especially across southwest to west-central Europe. There is risk of wet weather during late spring in Western Russia otherwise northeast of the Black Sea trends drier.

The key to wet periods in both the U.S. and to a lesser extent Europe/Western Russia is the frequency and strength of the Madden Julian oscillation. The MJO may be quite strong given passage over anomalous warm water in the central (and possibly the eastern) equatorial Pacific. If so, the mid-latitude storm tracks are affected and can produce significant rain in favored areas.

Fig. 2: January 2019 global soil moisture % of 30-year normal and 3-month forecast.

Across Asia more rainfall adds to wet conditions of South-central region. A dry pattern across India trends drier the next 3 months. The expected return of at least a weak El Nino implies a drier climate for Indonesia and northeast Australia. South Africa drought also intensifies.

Finally, in South America a drier than normal climate is projected across central and northeast Brazil while dry soils in east/southeast sections observe at least slight improvement. Wet weather is forecast to continue to aggravate wet soil conditions in Uruguay and vicinity. Central and southern Argentina are dry.