Weather Risk Overview

Weather Risk Overview Video

A project can experience negative impacts to its schedule and costs in the form of threat risks such as delays, accidents, malfunctions, and overruns. A project can also be impacted by a variety of weather-specific risks depending on its geographic location and the current season. Weather risks may include high winds, excessive wave height, flooding, and frozen bodies of water. These events can lead to periods of time where activity work cannot be performed, thereby threatening the finish dates and costs of individual activities and the project as a whole. You can use weather risk modeling to estimate periods of non-working time caused by weather events. Weather risk data is included in the risk analysis, enabling you to understand its potential impact on your project's schedule and cost.

Create weather risks to represent the individual weather events your project may experience. For each risk, define multiple weather periods and non-working estimates for each period to model how the risk's impact will change over time. Non-working time estimates are entered as a distributed range of days or as a percentage of non-work days within the weather period. Non-work percentage values are further enhanced by estimating the percentage of non-work days immediately following another non-work day, a weather modeling concept known as persistence. The recommended method for accurately estimating non-working time is to reference historical weather data for the type of weather event you want to model, the location of your project work, and the time of year in which the work will be performed.

After a weather risk is created, you should assign it to the activities that may be impacted by it. The non-working time estimates captured by each risk are applied to associated activities during the risk analysis. Weather risks without activity assignments are not included in risk analysis calculations.

Probabilistic Weather Calendar

After you add weather periods and non-working time estimates to your weather risks, you should ensure that each risk's weather data accurately models the corresponding weather event. Non-working probabilities are calculated and displayed in a probabilistic weather calendar for each weather risk. The probabilistic weather calendar runs a simulation of 100 iterations using the risk's period and estimate data. It then displays the non-working probabilities for each day that occurs in the risk's periods. The calendar is intended to be a visual confirmation that your weather data is being estimated as expected. You can revise your period dates and non-working time estimates and run the simulation again.

Use in Risk Analysis

Weather risks are included in the quantitative risk analysis calculations. The non-working time estimates are used when calculating varying durations and dates on the activities to which weather risks are assigned. Weather risk data contributes to the values shown in the Risk Analysis page charts.

Weather risks are not supported by the qualitative risk analysis. The probability and impact data represented by a project's risk matrix is not compatible with the varying non-working time estimates captured for weather risks. For this reason, separate pre-response and post-response values are not generated for weather risks. When running the quantitative risk analysis, the same weather risk data is used for activity-level calculations in both the pre-response and post-response contexts.

Weather modeling data generated by the risk analysis can be used to make more informed decisions during your project's planning phase. Consider the potential severity of each risk when developing strategies to reduce its impact on your project's schedule. For example, you may choose to schedule activities that could be severely impacted by rain to occur outside of the rainy season. In locations and seasons with higher likelihood of flooding, you might implement additional safety measures to protect your work site. If weather may affect the timeliness of material deliveries, you might consider reaching out to an alternate supplier. You can keep track of potential strategies by adding them as response actions to each risk.