NAM AIR QUALITY DIAGNOSTIC DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 1001 AM EDT MON AUG 08 2011 *** The following information pertains to initialization errors noted on the 12Z NAM that may negatively impact the performance of the 12Z CMAQ output as used for air quality forecasting. Specifically, errors that apply to temperature, winds, relative humidity and precipitation are included. This discussion only applies to geographical regions of the CONUS where air quality is currently forecast to be degraded (i.e. CODES: YELLOW/ORANGE/RED/PURPLE/MAROON). *** ...SOUTHERN CALIFORNIA... NO MAJOR INITIALIZATION ISSUES. ...TENNESSEE VALLEY AND MID-ATLANTIC... THE NAM IS TOO MOIST OVER THE WESTERN TENNESSEE VALLEY. GARRETT