Risk is difference than uncertainty. Knowing the difference is critical to the success of any project.
Risk
Risk stems from known probability distributions. Cost estimating methodology risks result from improper models of cost. Cost factors such as inflation, labor rates, and labor burdens impact cost risk. Configuration risk steams from the variation in the technical inputs to the project.
Schedule and technical risks are coupled in most projects. Understanding level of correlation between these random variables is critical to any projects success.
Mitigating risk is a programmatic solution that can be explicitly planned, scheduled and executed when encountered.
The risk response to a huricane can be laid out in an emergency response plan.
Uncertainty
Uncertainty stems from unknown probability distributions. How requirements impacts change is an example. Budget perturbations are another. Rework and retest impact project performance.
Mitigating uncertainty can be planned by not executed without first encountering the uncertainty, assessing its impact, and diverting resources to the "new" plan.
The probability that a huricane of Force 5 will strike the Gulf Coast is just that a statistical probability. If and when it does strike, the emergency response plan will most certaintly have to be revised.