What should be done if severe windshear conditions exist just prior to takeoff?

Delaying takeoff until the windshear subsides is the most prudent course of action when severe windshear conditions are present just prior to takeoff. Severe windshear can lead to sudden and unpredictable changes in wind direction and speed, significantly affecting the aircraft's performance during takeoff. By postponing the departure, the crew allows for conditions to stabilize, which can enhance safety for both the aircraft and those on the ground.

Making the decision to take off in such hazardous conditions can lead to a number of potential risks, including loss of control or an inability to achieve the necessary lift. Likewise, attempting to penetrate shear at low airspeed can increase vulnerability to this phenomenon, potentially compromising the aircraft's performance. While changing routes can be a consideration under certain circumstances, it is not always feasible or appropriate based solely on windshear alone. Therefore, exercising caution by delaying is the best practice in this scenario.