Types of weather forecasts and their use
A weather forecast predicts future weather from current observations, satellite images and computer models. In India the India Meteorological Department (IMD) issues forecasts. Forecasts are grouped by how far ahead they look:
- Nowcasting: for the next few hours; warns of thunderstorms, hail and heavy rain.
- Short-range forecast: for about 1 to 3 days; useful for daily jobs such as spraying, irrigation and harvesting.
- Medium-range forecast: for about 3 to 10 days; the most useful range for planning farm operations such as sowing, fertiliser application and harvesting.
- Long-range (extended/seasonal) forecast: beyond 10 days, up to a month or a season; e.g. the forecast of total monsoon rainfall. It helps choose crops and varieties and plan input supply.
Agrometeorological advisories combine the forecast with crop information and are sent to farmers through radio, TV, newspapers, SMS and mobile apps. They advise on what to do, for example: postpone pesticide spraying if rain is expected (rain washes chemicals off); delay irrigation if good rain is forecast; harvest and dry produce before a storm; protect crops and animals from cold waves and frost; take steps against heat waves.
Key points
- Nowcast: hours; short range: 1–3 days; medium range: 3–10 days; long range: beyond 10 days.
- Medium-range forecasts are the most important for planning farm operations.
- IMD is India's national weather agency.
- Agro-advisories turn weather forecasts into farm advice.
Exam tips
Questions usually give a time span and ask for the forecast type, or describe a farm decision and ask which forecast helps. Remember the boundary numbers 3 and 10 days.
Common mistakes
- Calling a seasonal monsoon forecast "medium range"; it is long range.
- Thinking forecasts only matter for rainfall; temperature, wind and humidity forecasts also guide spraying, frost protection and disease alerts.