 Over the next several days , Bilis moved generally northwestward toward Taiwan , slowly strengthening over open waters . Bilis was designated a severe tropical storm by the JMA on July 11 , but the storm did not strengthen much further over the next few days due to a marginal upper @-@ air environment and dry air entrainment . PAGASA upgraded the system to typhoon status on July 12 , but the JMA never officially recognized the system as such in its advisories . Bilis reached its official peak intensity of 60 knots ( 110 km / h , 70 mph ) later that day . 
