The document discusses various types of weather forecasting for agriculture including nowcasting, short range forecasting, medium range forecasting, and long range forecasting. It describes the different time periods each covers and how they can help farmers plan agricultural operations. Weather forecasting is important for agriculture because weather greatly impacts crop yields, and accurate forecasts can help minimize losses from adverse conditions.
2. The weather elements which influence the
agricultural operations and crop production can be
forecast upto different spans of time.
Weather forecast is defined as “prediction of weather
for the next few days to follow”.
Weather forecasting is foretelling the coming weather
in advance. It may be defined as advance information
about the probable weather conditions for few days
to follow.
3. ■ Weather is a dominant factor determine the success or
failure of agriculture enterprises. This is because farmer has
no control over over this natural force. Weather manifests its
influence on agriculture operations and farm production
through its effect on soil and plant growth.
■ Out of total annual crop losses, a sustainable portion is
because of aberrant weather condition.
■ But losses could be minimize by making the adjustment
with coming weather through timely and accurate weather
forecasting
■ Weather forecasting also provides guidelines for long range
seasonal planning and selection of crops most suited to
anticipated climatic condition.
4. Types of weather forecasting
Weather forecasting for agriculture may be divide in to four
types:
■ Nowcasting (few hours to one day)
■ Short range forecasting (24 hours to < 3 days)
■ Medium range forecasting (3-10 days)
■ Long range forecasting ( for >10 days, a month and for a
season)
5. Nowcasting
■ A weather forecast in which the details about the current weather and forecasts up to
a few hours ahead (but less than 24 hours) are given.
■ It is a powerful tool in warning the public of hazardous, high-impact weather including
tropical cyclones, thunderstorms and tornados which cause flash floods, lightning
strikes and destructive winds.
6. Short range forecasting (SRF)
■ It is the forecast and warning of
weather elements hazardous to
agriculture valid for 36 hours and an
outlook for subsequent 3 days.
■ The SRF is issued twice a day based on
synoptic conditions.
■ Though SRF is use full in weather based
agricultural operations, the reaction
time available to formers is too short
for preventive measures against
adverse weather.
■ The error in forecast ranges from 20-30
per cent.
■ The SRF includes
– cloud spread,
– rainfall distribution,
– heavy rainfall waning,
– maximum and minimum
temperature,
– heat and cold waves,
– low pressure area,
– cyclone warning,
– hail storm and dust storm,
– snow, frost and
7. Medium range forecasting (MRF)
■ It is the forecast and warning of weather elements hazardous to agriculture valid for 3-
10 days.
■ The MRF is an objective and challenging one to weather scientists as it involves
enormous numerical computations with expertise in weather sciences.
■ A national center for medium range weather forecasting (NCMRWF) was established
in 1988 in new Delhi to develop atmospheric model for medium range weather
forecasting.
■ This forecast is issued twice in a week i.e. on Tuesday and Friday. Forecast error ranges
from 30 to 40 per cent.
■ Forecast includes
– cloud amount,
– rainfall,
– maximum and minimum temperature
8. long range forecasting (LRF)
■ It is the forecast for more than 10 days, a month, a season.
■ IMD started issuing the long range forecasting since 1988 onward on total monsoon rainfall of the
country by 25th may.
■ The predicted and actual long period average of monsoon (June –September) rainfall of the country were
in agreement except in1994.
■ This forecast is issued region wise i.e. country is divided in four zones:
(1) North eastern region
(2) Central region
(3) NorthWestern Region
(4) Peninsular region.
The forecast error varied around 40 per cent.The weather parameters on which forecast have been issued as
under
- Onset of monsoon rains
9. Significance of weather forecasting in
agriculture
■ Agriculture is mainly dependent of weather. If the weather is favourable, then crop
production will be higher. But if the weather is not under optimum/favourable range,
then it will cause losses to crop production depending upon its intensity of
abnormality. Such type of weather is termed as aberrant weather or abnormal
weather. However the losses due to aberrant weather can be minimized if it is
forecasted accurately. Rather it is impracticable to avoid crop losses due to aberrant
weather but it is possible to minimize crop losses to some extent, if weather forecast is
accurate and in time.
■ The input cost can be minimized by avoiding wastage of inputs through short term
adjustment of input applications with coming weather. The applications of forecasting
also depend upon the lead time of forecasting. So the applications can be grouped
with the type of forecasting:
10. Short range applications
■ Adjustment of day to day field operation
■ Scheduling of irrigation and application of agro-chemicals
■ Protection of field crops & livestock from frost/cold wave &
heat wave
■ Efficient use of labour
11. Medium range applications
■ Sowing and planting of crops
■ Management of labour, irrigation water and agro-chemicals
■ Protection measures against frost/cold wave and heat wave
■ Management of inputs and products of livestock
■ Transportation of farm products
12. Long range applications
■ Selection of crops, varieties and breeds
■ Management of water resources
■ Management of farm inputs such as labour, machinery, seeds
13. Climatic / agro climatic forecasting
■ It requires past meteorological data for a good numbers of years (say 30-50 years) the
trends in rainfall and its variability, probability on the distribution of rainfall over a
season can be determined weekly using the past data on the rainfall for a given
location.
■ This information is useful to crop planners and farmer as crop growth periods can be
adjusted under rainfed conditions depending upon rainfall probabilities.
■ the climatic trends also helps in understanding the impact of climatic variability on
agricultural production over a period of time.
14. Different tools used in weather
forecasting
■ Pilot balloons
■ Radiosnodes
■ Radar
■ Satellites
■ Surface data
16. Synaptic method
■ The atmosphere at an area is known at an instant through a set of meteorological
variables, viz. rainfall, maximum and minimum temperature, wind and pressure
system measured simultaneously at various locations. These observation are called
synoptic.
■ Using the observation recorded simultaneously, surface and upper air chart are
prepared which give the present state of atmosphere.
■ The inference on expected movement of weather system is drawn using previous and
present charts.
■ In addition to synoptic charts, satellites picture also supply considerable information
evolved on the lines of the past analogous one.
■ Often, selection of past analogous situation is based on experience and memory of the
person involved, but with the advent of computer picking up of analogies is quite easy
and became faster and more objective.
17. Statistical method
■ The statistical method are mostly used in long range and climate forecasting.
Techniques based on multiple regression and auto regressive integrated moving
average (ARIMA) are used for predicting Indian monsoon rainfall based on 16 global-
land-ocean-atmospheric variables.
■ Using above technique, the total rainfall during south-west monsoon is predicted well
in advance during the last week of may.
■ The technique is working well for prediction of total monsoonal rainfall of the country.
However the ARIMA model fail on metrological sub division wise since the model are
not area specific.Also, model needs testing, verification and validation regularly.
18. Numerical weather prediction
■ Thinkers frequently advance ideas long before the technology exists to implement
them. Few better examples exist than that of numerical weather forecasting. Instead
of mental estimates or rules of thumb about the movement of storms, numerical
forecasts are objective calculations of changes to the weather map based on sets of
physics-based equations called models.
19. Reliability of weather forecasting
depends on
■ Awareness of the observer on the
importance of weather forecasting
■ Network of observatories- surface and
upper air stations
■ Dissemination role of telecommunication
network like AIR DD and news media
■ Type of weather forecasting (SRF, MRF
and LRF)
■ Efficiency of space tool
■ metrological data and past analogies
■ Skill and experience of weatherman
■ Present day technology knowledge gain
in the field of weather forecasting
■ Weather analysis and generation of
computer output- how fast it dose
■ Communication of data from collection
to weather forecasting center
■ Frequency of data collection
■ Timely and correctness of the
observation
20. Weather services to farmers
■ A reliable system of short range and medium range weather forecast is need for
effective on farm management practices such as cultivation of land preparation
of seed bed, planting, choice of crop in case of prolong monsoon break, fertilizer
management, harvesting of crop, post harvest storage and transportation to
markets.■ IMD started issuing farmers weather bulletin (FWB) on regular basis since 1945 and later it was
entrusted to regional meteorological centers (New Delhi, Mumbai, Calcutta, Chennai, Nagpur),
which contain a forecast of expected weather for 36 hrs. and an outlook for another 2 days.
■ In due course, meteorological center at state head quarters started to issue FWB’s.
■ All India radio used to broadcast FWB’s every evening in regional languages to reach the most
remote corner. However, they are found to fall short of requirement of farmers in terms of
duration of forecast validity and capability for small areas, likely impact on agronomic
operations. The crop weather calendars prepared for main crops last their significance with fast
changing varieties. As they contain limited information there was need to frame them in
relation to crop and to specific areas. Thus came the concept of agrometeorological advisory
services (AAS) and it is in operation.And it is in operations since 1977
21. Agro-met advisory services (AAS)
■ The AAS based on Medium range weather forecasting (3-10 days) as been made operational
by national center for medium range weather forecasting (NCMRWF). The ICAR and SAU co-
operates in this task. NCMRWF has proposed to establish 127 Agrometeorological field units
(AMFU’s) in all the agro climatic zones, which over the entire country. The agro climatic zones
were delineated by the ICAR under NationalAgricultural research project (NARP).
■ AMFU’s prepare ASS bulletins. These contain three parts. The first part of AAS consist of
weather events occurs during past week and weather forecast for next three days ahead.
These forecasts are given to acquaint the farmers with the expected weather on cloud
amount, rainfall, average wind speed, wind direction, maximum and minimum temperatures.
■ The second part contains the factual information on the varieties of crops their state and
stage, on going agricultural operations, and insect pest and disease of crops.
■ Final part consist information on the agro advisory.
■ Bulletin are prepared by the expert consist of Agricultural scientist of various disciplines and
agricultural officers of the locality in English and local language
■ The Agro met Advisory Service Units issue biweekly agro advisories to the state on Monday
and Thursday based on medium range forecasting. These describe weather over the state
22. National agro met advisory bulletin
■ The bulletin is prepared for national
level agricultural planning and
management and is being issued by
national agromet advisory service
center, agriculture meteorological
division, IMD.
■ The prime user of this bulletin are
crop weather watch group(CWWG),
Ministry of agriculture.
■ Bulletin is also communicated at all
other related ministries (state and
central), organization and NGO’s for
their use.
23. ■ This bulletin is prepared for state level
agriculture planning and management.
■ This bulletin are issued for 22 AAS
units at different state capitals.
■ Prime user of this bulletin state
ACWWG. This is also meant for other
user like fertilizer industry, pesticide
industry irrigation department seed
corporation, transportation and other
organizations which provide input in
agriculture.
State agro met advisory bulletin
24. District agro met advisory bulletin
■ This is prepared for the farmers of the district.
■ This bulletin are been issued from 30 AMFU’s functioning at state agricultural
universities.
■ This contains advisories for all the weather sensitive agricultural operations from
sowing to harvest.
■ It also includes advisories for horticultural crop and live stock.
■ This weather based advisories are disseminated to the farmers through mass media
dissemination, internet etc.. As well as through district level intermediaries.
■ The advisories will be communicated through multi channel dissemination system.
27. ■ Detailed information for each
important crop on their dates of
sowing, dates of commencement
and duration of major cultural
operations, important periods in
their life cycle and their most
probable weather requirements
have in India been presented in a
pictorial form called the “Crop
Weather Calendar”.
■ Such calendars have been prepared
for each state (province) covering all
the important crops grown.
■ The crop weather calendars consist
of three parts.
CropWeatherCalendars in India
28. ■ Climatic data requirement
Weekly climatic normal for standard meteorological weeks for each
computed for all AICRPAM centers. These normal meteorological data sets were
in a weekly format for the cropping season from the month of sowing till the
the crop in question.
■ Information on crop phenology
Crop phenological information collected from sowing to maturity is
a weekly basis. Important ‘phases’ like sowing, germination / emergence,
case of rice), vegetative growth, f lowering, grain formation and maturity are
per the Standard Meteorological Weeks. Further, information on the favorable
meteorological conditions for the crop (stage-wise or whole crop growth period)
lead to high yield were deduced from the long-term experimental data and
■ Information on pest and diseases
The data on weather conditions favorable for incidence of pests and
the nature of the weather warnings were collected.
Structure of crop weather calendar
