World Grain - January 2020 - 68

FEATURE: INDONESIA SEEING MORE RAINFALL

peratures were so warm in the western Indian Ocean
that record-setting rainfall occurred in eastern Africa
DQGÀRRGLQJZDVKRUUL¿FLQPDQ\DUHDV,QGLD¶VPRQAverage 7-day topsoil moisture ended Dec. 27, 2019
soon was so enhanced with moisture from the warm
ocean water that the seasonal rains had a hard time shutting down, and then there was Indonesia and northern
$XVWUDOLDWKDWVX൵HUHGIURPVHULRXVGU\QHVVHDUO\LQWKH
year and were having a tough time getting rainfall even
though there was no El Niño. The Indian Ocean Dipole
phenomenon was breaking down in the fourth quarter of 2019. Ocean temperatures in the western Indian
Ocean were cooling while warming was evolving from
the eastern Indian Ocean into the Indonesian archipelago. As a result of this change, rain began falling
Average 7-day topsoil moisture ended Nov. 1, 2019
in southern Indonesia. Rain during the 30-day period
ending in late December was occurring more routinely
due to the change in ocean temperature anomalies and
a southward shift in the Inter-Tropical Convergence
Zone, which we will cover in another article.
Australia's drought might not have prevailed as extremely as it did in 2019 had it not been for the reFRUG SRVLWLYH ,2' DQG D SRRO RI VLJQL¿FDQWO\ ZDUP
ocean water near the equator near the International
Dateline. The cool water northwest of Australia and
to the east of Sumatra, Indonesia, and the warm waMoist
Extremely wet
Dry
Marginal
ter near the International Dateline and in the western
Adequate
Wet
Limited
Indian Oceans were helping to create a massive region
of higher-than-usual pressure over northern Australia
The longer the warm water remains in place, the higher and southern Indonesia. The high-pressure system
the potential is for additional precipitation.
prevailed for most of the Southern Hemisphere spring
A few years ago, when the Gulf of Alaska was colder and early summer, preventing rain from developing in
than usual, storm systems were not gaining moisture Australia's key grain, oilseed and cotton areas in the
or lift from the ocean because the cool water was sup- south and east, making the 2017-18 drought turn into a
pressing rising motions in the atmosphere. This in third year and helping push the drought to record proturn suppressed rainfall downstream across Canada's portions in some eastern areas of Australia.
Prairies, resulting in drought.
It will take little longer but as IOD breaks down and
In 2019, western Indian Ocean water temperatures ocean water north of Australia warms up, the highVRDUHG ZHOO DERYH DYHUDJH ZKLOH WKH ZDWHU R൵ WKH pressure system in Indonesia and northern Australia
southwest coast of Sumatra, Indonesia, was colder than will break down more completely. Rain should begin
usual. The anomalies set records of extreme and some falling in northern and eastern Australia as well as
of the cold water southwest of Sumatra worked its way southern Indonesia over the next few weeks as these
into Indonesia's archipelago. The cold water from the changes prevail. Drought may not completely end in
eastern Indian Ocean into the Indonesian archipelago Australia, but the prolonged rain-free period and excesresulted in suppressed rainfall in Indonesia and north- sive heat should soon abate.
ern Australia. The persistence of this feature resulted in
prolonged dryness in southern Indonesia, even though
Drew Lerner is senior agricultural meteorologist with World
there was no El Niño event. Scientists used to believe
Weather, Inc. He may be reached at worldweather@bizkc.
that the only way to get drought in Indonesia was from
rr.com. World Weather, Inc. forecasts and comments pertaining to
El Niño. This year proved that theory wrong.
present, past and future weather conditions included in this report
RELIEF FOR INDONESIA
The unusually warm ocean water in the western Indian
Ocean and cold water in the east is called the positive
phase of Indian Ocean Dipole (IOD). This year's tem68

constitute the corporation's judgment as of the date of this report
and are subject to change without notice.
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January 2020 / World Grain / www.World-Grain.com

World Weather Inc.

Indonesia and Malaysia topsoil moisture

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World Grain - January 2020

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