WSMP31 LMMM 190900 SIGMET LUQA AIRFIELD WARNING NO. 30 THUNDERSTORM T.O.O. 19/0837UTC THUNDERSTORMS MAY AFFECT LUQA AIRFIELD WITH BKN CB BASE 1500FT ABOVE LUQA AIRFIELD. VIS MAY FALL TO 3000M AND WIND GUSTS MAY REACH 25KT. VALID TILL 19/1100UTC=