Choose a recurring decision that may change depending on the expected weather. It could involve preparing a farm for heavy rain, rescheduling a task or adjusting work in a greenhouse. The examples are hypothetical and their figures are illustrative; they do not correspond to a client. If you are missing a piece of information, write down what you need to find out. You can proceed with an estimate as long as you identify it as an estimate.
Part one: write the rule
1. Choose the decision
Example: Prepare the ponds at a shrimp farm for an episode of heavy rain, several times during the rainy season.
Include the location, period and weather condition that affects the work. “Heavy rain” needs a definition that the technical manager can connect to the management of the farm.
2. Estimate the costs
For a preparation that reduces damage if the event occurs, write down your estimate and where it comes from, or what still needs to be checked.
The avoidable loss is the difference between the previous two figures. Use that amount in the calculation: threshold (%) = cost of preparing ÷ avoidable loss × 100.
Example: Preparation costs $300 and can prevent a $10,000 loss. The break-even point is 3%. A forecast probability of 5% is above that threshold.
This calculation compares expected monetary costs under the assumptions in the first guide. If you cannot estimate how much damage the measure prevents, leave the result pending. If rescheduling creates other losses or the decision has constraints that the calculation does not capture, write them down before adopting the rule.
3. Assign the action and its timing
Complete the sentence using the same event and threshold as in the calculation.
If the probability of exceeds %, authorises and carries it out. We need to prepare.
Example: If the probability of the defined rain event exceeds 3%, the farm manager authorises the preparation agreed with the technician and the pond team carries it out. The timing must be completed with the actual time needed at that farm.
4. Set the last time for waiting
Write down the last date and time at which an update would still allow the action to be carried out. Include the time needed to organise staff.
Write down what it is, if one exists, and its cost. There will not be one in every case.
5. Record other decisions
Repeat the exercise with other actions, if appropriate. Use the threshold only where the assumptions of the calculation are valid.
| Decision | Person responsible | Cost of preparing ($) | Avoidable loss ($) | Threshold (%) |
|---|---|---|---|---|
Part two: put the decisions in time order
6. Choose a season or a job
Example: Delivering flowers for Valentine's Day. Production is scheduled months ahead; as delivery approaches, daily work is organised and management is adjusted to local conditions.
Complete the rows that make sense for your case. The time frames are prompts for thinking and can be changed. An information need recorded here must still be compared with what a forecast can provide.
| What can you decide or change? | What do you need to know about the weather? | |
|---|---|---|
| 3 months | ||
| 15 days | ||
| 7 days | ||
| 24 hours | ||
| 1 hour |
Review the rows with the person who would carry out each action. Check that the time available is sufficient and identify the decisions for which you still lack useful information.
7. Gather information from the operation
Record the area and any differences between locations that could change the decision.
These may include logbooks, work dates, expenses or losses. Identify which information comes from records and which comes from the team's memory.
8. Return to the rule after using it
Keep the forecast used, the time of the decision and the action carried out. During the review, record what happened and how much it cost. Consider several events before judging the rule: one day when you prepared and it did not rain is not enough on its own to justify keeping or changing it.
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