NAM AIR QUALITY DIAGNOSTIC DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 1041 AM EDT TUE AUG 28 2012 *** 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). *** ...TENNESSEE/OHIO VALLEYS... NO NAM INITIALIZATION ISSUES WERE NOTED. ...MIDWEST TO UPPER MISSISSIPPI VALLEY... THE NAM WAS UNDERDONE IN INTENSITY AND BETWEEN 100-200 MILES TOO FAR NORTH WITH A DECAYING AREA OF PRECIPITATION MOVING THROUGH SOUTHERN MINNESOTA BETWEEN 1200 AND 1400 UTC. ...SOUTHERN PLAINS... THE NAM WAS OVERDONE WITH THE COVERAGE AND MAGNITUDE OF PRECIPITATION ALONG THE RED RIVER INTO THE ARKLATEX. ...INTERMOUNTAIN WEST AND COLORADO FRONT RANGE... THE NAM WAS ABOUT 5-10 TOO COOL ACROSS THE SALT LAKE CITY METRO REGION. OTHERWISE...NO NAM INITIALIZATION ISSUES WERE NOTED. ...ARIZONA/SOUTHERN NEVADA/CALIFORNIA... THE NAM ANALYZED TEMPERATURES 5-10F TOO COOL ACROSS THE DESERTS OF EASTERN CALIFORNIA...SOUTHERN NEVADA INTO WESTERN ARIZONA. THE NAM ANALYZED TEMPERATURES 5-10F TOO WARM ALONG COASTAL SECTIONS OF SOUTHERN CALIFORNIA BETWEEN ROUGHLY IRVINE TO SANTA MARIA. THE NAM NEAR-SURFACE RELATIVE HUMIDITY FIELDS WERE TOO DRY ALONG THE SOUTHERN/CENTRAL CALIFORNIA COAST...WEST OF SANTA MARIA...WHERE SOME FOG WAS OBSERVED. OTTO