NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1024 AM EDT TUE JUL 05 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). ***

...MID-ATLANTIC STATES/NORTHEAST/OHIO VALLEY/GREAT
LAKES/MIDWEST...

THE NAM 500MB HEIGHTS WERE INITIALIZED WITH A GENERAL NEGATIVE
BIAS WITH SOME POSITIVE BIAS IN THE MID-ATLANTIC REGION. WINDS AT
250MB WERE INITIALIZED CLOSE TO THE OBSERVED. THE MID-AND
UPPER-LEVEL MOISTURE PLUME IN THE UPPER MIDWEST APPEARS TO BE
INITIALIZED TOO FAR WEST WHEREAS THE LOW-LEVEL MOISTURE COMPARES
WELL WITH THE OBSERVED.


...SOUTHERN PLAINS...

THE NAM 500MB HEIGHTS WERE INITIALIZED WITH A POSITIVE BIAS. WINDS
AT 250MB WERE INITIALIZED WEAKER THAN THE OBSERVED NEAR THE GULF
COAST. ATMOSPHERIC MOISTURE APPEARS TO MATCH THE OBSERVED QUITE
WELL IN THE MID AND UPPER-LEVELS BUT IS TOO DRY NEAR THE CENTRAL
GULF COAST.


...SOUTHWEST/CALIFORNIA...

THE NAM 500MB HEIGHTS WERE INITIALIZED WITH A NEGATIVE BIAS. WINDS
AT 250MB WERE INITIALIZED SLIGHTLY WEAKER THAN THE OBSERVED.
ATMOSPHERIC MOISTURE APPEARS TO MATCH THE OBSERVED REASONABLY
WELL.


KONG