NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1018 AM EDT MON JUN 13 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). ***


...OHIO VALLEY/LOWER GREAT LAKES...

THE NAM HAS INITIALIZED TEMPERATURES 5 TO 7 DEGREES F WARMER THAN
OBSERVED OVER NORTHERN OHIO JUST SOUTH OF LAKE ERIE.


...TENNESSEE VALLEY/SOUTHEAST...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.


...MISSISSIPPI VALLEY...

RAINFALL OBSERVED OVER MISSOURI APPEARS TO HAVE GREATER
COVERAGE/INTENSITY THAN INDICATED NEAR THE BEGINNING OF THE NAM
FORECAST.


...SOUTHERN HALF OF THE PLAINS...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.


...DESERT SOUTHWEST/CENTRAL VALLEY OF CALIFORNIA...

OBSERVED TEMPERATURES AT SOME LOCATIONS OVER INTERIOR SOUTHERN
CALIFORNIA AND EXTREME SOUTHERN NEVADA ARE AT LEAST 10 TO 15
DEGREES F WARMER THAN INITIALIZED BY THE NAM.  MORE LOCALIZED
AREAS WITHIN THE CENTRAL VALLEY OF CALIFORNIA HAVE OBSERVED
TEMPERATURES UP TO 5 TO 10 DEGREES F WARMER THAN THE NAM
INITIALIZATION.  MEANWHILE WINDS TO THE NORTH/NORTHEAST OF LOS
ANGELES ARE OBSERVED FROM THE NORTH OR WEST AT 10 TO 15 KNOTS
VERSUS INITIALIZED WINDS OF 5 KNOTS FROM THE WEST.  


RAUSCH