[Ref US AIM Section 3 Airport Operations 4-3-7]
How do pilots know if there is low-level wind shear (LLWS) near airport? (in USA)
Ans: Controllers (ATC) will provide low-level wind shear (LLWS) information to pilots by giving the pilot the airport wind followed by the boundary wind.
Wind shear alert, airport wind 230 at 8, south boundary wind 170 at 20.