The observability of the Higgs signal in the mass range of 200-800 GeV is investigated in the weak boson fusion channel at the CMS experiment at LHC. The weak boson fusion channel is characterized by two final state jets at large pseudorapidity. The forward calorimeter plays a key role in detecting these jets. The significant signals are obtained for H --> WW --> lvjj, H --> ZZ --> lljj and H --> ZZ --> llvv. Importance of the forward jet tagging and the central jet veto is emphasized to extract the signal from the large QCD W/Z + jets and the top backgrounds. This analysis shows that the Higgs particle with mass 300 GeV to 800 GeV can be observed in WW and ZZ decay channels with an integrated luminosity of about 10 to 120 fb(-1) in the low luminosity running conditions in CMS.