Climate Exchange

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Seasonal climate prediction in Chile:

the Agroclimate Outlook

Juan Quintana, Benito Piuzzi and Jorge F. Carrasco, Dirección Meteorológica de Chile –

Dirección General Aeronáutica Civil; and Liliana Villanueva,

Ministerio de Agricultura, Unidad de Emergencia Agrícola

he Agroclimate Outlook is a monthly bulletin produced

by the Dirección Meteorológica de Chile (DMC) and freely

available in the organization’s website. It contains infor-

mation about the predicted seasonal climate conditions that

are most likely to prevail during the next three months. The

total precipitation accumulation and the average minimum

and maximum air temperatures for the three-month period are

predicted variables, which are considered for analysing and

predicting the implications in the agriculture sector. The seasonal

forecast is based on the correlation between the El Niño Southern

Oscillation (ENSO) and the predicted variables in Chile.

Agricultural meteorology deals with the relationship between

weather and climate and crop, livestock and soil management.

Agricultural activity carries implicit risks of diverse origins,

among which, are atmospheric factors. Generally speaking, these

factors can be weather- or climate-related, according to the dura-

tion of the meteorological event. Thus, phenomena that develop

and have a lifetime from a few hours to a week are considered

weather-related and their forecasts are produced at least on

a daily basis. On the other hand, there are other phenomena

griculture

whose genesis and duration involve longer periods

of time, from few weeks to months or even years.

These are considered climate-related and their fore-

casts are produced and disseminated on a monthly

basis. Weather or climate forecasts, regardless of their

characteristics, do not refer to or indicate the degree

of risk given by the prediction; they rather express

and inform users on the degree of likelihood that a

meteorological event can occur in a given time and

place. Atmospheric factors can have implications

on agriculture and related activities, and knowing

in advance how they will develop (forecasts) and

affect a region can help farmers and decision-makers

to take actions for mitigating or benefiting from the

predicted atmospheric conditions. For example, they

can receive information for better agriculture water

management, for planning periods of planting and

harvesting, for improving livestock management or

for altering grazing and rotation pastures.

The natural climate variability in Chile often results

in extreme meteorological events, such as droughts,

floods, cold waves (including frost), heat waves and

sometimes severe thunderstorms and hailstorms. These

extreme phenomena occur on different temporal and

spatial scales – thunderstorms and floods can last a few

hours, while frosts and droughts might last for days or

even months; and while some events might affect a small

area, others will be of synoptic scale, affecting a large

region. This variability is the result of natural processes

that, alone or combined with others, can develop an

atmospheric condition triggering and supporting the

occurrence of a meteorological event. For instance,

frost days are mostly caused by very cold air masses

moving behind a frontal band. Periods with little or no

precipitation during the winter, or a rainy period (three

to four weeks) in central Chile (30-40° south) can be

associated with atmospheric alterations caused by the

Madden-Julian Oscillation,

which is an intra-seasonal

climate variability that takes place in the equatorial

band of the Indic and western Pacific ocean region with

a recurrence period of 30-60 days. On the other hand,

under or above annual normal precipitation in Chile is

most likely associated with the inter-annual variabil-

ity caused by ENSO, which is an oceanic-atmospheric

Source: DMC

The most frequent weather and climate risks in Chile