NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1016 AM EDT THU JUL 26 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...
...SOUTHERN NEVADA...

THE NAM INITIALIZES TEMPERATURES 10-20 F LOWER THAN OBSERVED OVER
SOUTHERN PORTIONS OF INTERIOR CALIFORNIA AND EXTREME SOUTHERN
NEVADA. 

...NORTHERN UTAH...

WINDS EAST OF THE GREAT SALT LAKE DIFFER AS MUCH AS 90 DEGREES
FROM OBSERVED.  THE NAM IS INITIALIZED WITH WESTERLY
WINDS...WHEREAS OBSERVATIONS INDICATED SOUTHERLY WINDS. 

...PACIFIC NORTHWEST...
...DESERT SOUTHWEST...
...CENTRAL ROCKIES/HIGH PLAINS...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.

...MID MISSISSIPPI VALLEY...
...OHIO VALLEY...
...GREAT LAKES...
...TENNESSEE VALLEY...
...SOUTHERN MID ATLANTIC...
...SOUTHEAST...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.

...NORTHERN MID ATLANTIC...
...NORTHEAST...

THE NAM APPEARS TO BE UNDER-REPRESENTING THE LINES OF SHOWERS AND
THUNDERSTORMS THAT WERE ADVANCING EASTWARD ACROSS NORTHERN
MARYLAND...SOUTHERN PENNSYLVANIA...NORTHERN NEW JERSEY...SOUTHERN
NEW YORK...INCLUDING LONG ISLAND...AND SOUTHERN NEW ENGLAND.  THE
NAM ALSO UNDER-REPRESENTED A SEPARATE AREA OF SHOWERS AND
THUNDERSTORMS THAT MOVED INTO NORTHWESTERN PENNSYLVANIA AND
WESTERN NEW YORK.


PEREIRA