NAM AIR QUALITY DIAGNOSTIC DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 1005 AM EDT TUE JUN 12 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). *** ...INTERIOR VALLEYS OF CALIFORNIA... THE NAM INITIALIZED SURFACE TEMPERATURES AS MUCH AS 10 TO 15 DEGREES TOO LOW NEAR THE EDGE OF THE TERRAIN OVER SOUTHERN CALIFORNIA...MOST LIKELY DUE TO ELEVATION RESOLUTION WITHIN THE MODEL. ...NORTHERN FRONT RANGE OF COLORADO... THERE WERE NO SIGNIFICANT INITIALIZATION ERRORS NOTED WITH THE NAM OVER THIS REGION. ...EAST TEXAS AND LOUISIANA... THERE WERE NO SIGNIFICANT INITIALIZATION ERRORS NOTED WITH THE NAM OVER THIS REGION. CISCO