In this study, various observations were ingested through WRFVAR system to simulate the intensity and track of Hurricane Katrina 2005. These observational data include ADP surface and upper air observations, QuickScat (microwave scatterometer SeaWinds), Airborne GPS radio occultation data ( from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Data Analysis and Archival Center (CDAAC) ), Special Sensor Microwave/Imager (SSM/I) retrieval and brightness temperatures at the seven channels. For each simulation, only one type of observation has been assimilated into model. The analysis focuses on the hurricane intensity and track deviation against the observed (best track) based upon 6h interval. One-month retrospective run of WRF model has been conducted to derive Background Errors Statistics with control variable option of cv_option=5 (new NMC approach for regional application). The preliminary results showed that assimilating ADP surface and upper-air and GPS radio occultation observations have improved the track forecast within 48h, where ADP provides the best forecast. But QuickScat observation degrades the track forecast. It was also noticed that all experiments missed to capture the central intensity of hurricane based on either minimum SLP or maximum sea surface wind speeds. The further result analysis will be presented during meeting.