WSCN25 CWAO 180831 CZUL SIGMET U2 VALID 180830/181230 CWUL- CZUL MONTREAL FIR FRQ TS OBS AT 0830Z WI 40NM WID LINE BTN /N4847 W07804/45 N CYVO - /N4606 W07922/15 S CYYB TOP FL460 MOV ENE 25KT WKN RMK GFACN33/CZYZ TORONTO FIR SIGMET P4=