NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1009 AM EDT MON AUG 13 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...
DESERT SOUTHWEST...

THE NAM INITIALIZED SURFACE TEMPERATURES AS MUCH AS 15 DEGREES TOO
LOW NEAR THE MOUNTAINS DUE TO ITS TERRAIN RESOLUTION.

EASTERN WASHINGTON...

THERE WERE NO SIGNIFICANT INITIALIZATION ERRORS NOTED WITH THE NAM
IN THIS REGION.


SNAKE RIVER VALLEY OF IDAHO...
NORTHERN WASATCH FRONT...

THE NAM INITIALIZED SURFACE WINDS AS MUCH AS 10 KTS TOO WEAK IN
SPOTS.


FRONT RANGE OF COLORADO...

WIND DIRECTIONS DIFFER BY AS MUCH AS 90 DEGREES IN SOME LOCATIONS.


CENTRAL OKLAHOMA...
EAST TEXAS...

THERE WERE NO SIGNIFICANT INITIALIZATION ERRORS NOTED WITH THE NAM
IN THESE REGIONS.


LOWER OHIO AND TENNESSEE VALLEYS...

THE NAM IS UNDERESTIMATING THE INTENSITY OF THE HEAVY RAINFALL
BANDS MOVING ACROSS THE REGION THIS MORNING.

UPPER OHIO VALLEY...
MID ATLANTIC...
SOUTHEAST...

THERE WERE NO SIGNIFICANT INITIALIZATION ERRORS NOTED WITH THE NAM
IN THESE REGIONS.


PEREIRA