Progress of Time-lagged North America Rapid Refresh Ensemble Forecast System (NARRE-TL) and its Verification

The NCEP's Time-lagged North America Rapid Refresh Ensemble Forecast System (NARRE-TL) has been successfully implemented along with the Rapid Refresh model (RAP) in May 2012. Based on both North America Mesoscale (NAM) model and RAP of NCEP as base models, the NARRE-TL has 13km horizontal resolution covering CONUS and Alaska regions, hourly updated out to 12 hour forecast. Aiming at providing ensemble guidance to aviation weather prediction, the products of NARRE-TL include multiple levels of icing, jet stream, and turbulence (Clear Air Turbulence), surface visibility, fog, ceiling height, convection, simulated radar reflectivity, precipitation types, and accumulated precipitation. The general process and configuration have been reported on the 15th Conf. on Aviation, Range and Aerospace Meteorology (ARAM, 2011). In this report, the focus will be on grid-to-grid verifications of 3 NARRE products, including visibility, icing and reflectivity against 2.5km-RTMA's visibility, AWC/NCAR's ADDS CIP analysis and NCEP/OU's radar moasic data, respectively. The general methodology of the grid-to-grid verifications for these 3 products will be introduced. To compare with the skills of RAP and NAM, the performances of the same products for both RAP and NAM are also verified. The results based on the past 6 months will be presented and be discussed.