The Profound Influence on Asia/Australia Soil Moisture by the +IOD

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Highlight: FEB/MAR/APR 2020 brings wetter Northern U.S./Western Europe climate. Central Argentina drought worsens and patchy rains arrive in Australia.

Fig. 1: The NOAA/CPC soil moisture ranking percentile valid December 2019 with annotated 3-month trend.

Observation discussion: Most prolific is the widespread dryness and drier trend across Australia during quarter 4 of 2019 (Fig. 1). The drier trend in Southeast Asia and widening wet signature across East Africa and South-central Asia – each very profound soil moisture trends are all part of the climate pattern produced by a historic positive phase of the Indian Ocean Dipole (Fig. 2). The +IOD pattern is fading as 2020 arrives.

In South America East Brazil trended drier during Q4 of 2019 while dryness in Central Brazil eased. Previously, a wet signature across Argentina also eased as soil moisture is now neutral. Central Argentina is steadily dry. The wet change across Peru was due to influence of transient Madden Julian oscillation/Kelvin Wave activity.

In the U.S. a wetter regime associated with warm regions of ocean water near and east of Hawaii and across the western North Atlantic was observed across Mexico into the Southwest U.S. and throughout much of the East U.S. Only the Northwest (and Texas) have been dry spots in the U.S. Western Canada has also been drier.

Western Europe turned wetter during late 2019 while the Black Sea region is much drier. Northwest and Central Russia were wetter during Q4 of 2019.

Fig. 2: The seasonal global SSTA analysis for quarter 4 of 2020.

Forecast discussion: The outlook based primarily in the global NMME SSTA and rainfall anomaly outlook valid for FEB/MAR/APR 2020. Expected is already wet soil moisture conditions in the Midwest U.S. and into the Northeast States to trend wetter while the recent wet trend in the Southwest U.S. reverses drier (Fig. 3). In South America Northeast Brazil turns wetter while northern South America drier due to the influence of the negative phase of the Atlantic meridional mode (-AMM). Meanwhile central Argentina encounters drought.

Western Europe is likely to turn drier while the dryness in the Black Sea region is steady. Much of Northern Russia remaining drought is eased by a wetter pattern into the spring months.

Northern India to China are wet during the period while Southern India turns drier. Western Indonesia trends drier while eastern Maritime Continent is drier. A wet forecast is indicated for South-central Australia while western continent trends drier. South Africa drought worsens.

Fig. 3: The NOAA/CPC soil moisture ranking percentile valid December 2019 with annotated 3-month forecast.