NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1028 AM EDT THU JUL 07 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/OHIO VALLEY/SOUTHEAST...

THE 12Z NAM SURFACE TEMPERATURES AND WINDS COMPARED WELL WITH
OBSERVATIONS. HOWEVER...THERE IS A STRONG MOISTURE GRADIENT IN
NORTHERN NC WHICH WAS NOT ANALYZED WELL BY THE 12Z NAM.
SPECIFICALLY...THE GREENSBORO NORTH CAROLINA SOUNDING SHOWS A PW
OF 1.84 INCHES. 
THE 12Z NAM ANALYZED ONLY ABOUT 1.5 INCHES AT GREENSBORO.  THE MID
AND UPPER-LEVEL MOISTURE COMPARED WELL WITH INFRARED IMAGES.

...SOUTHERN PLAINS...

THE 12Z NAM SURFACE TEMPERATURES...WINDS AND MOISTURE FIELDS WERE
ANALYZED WELL COMPARED WITH OBSERVATIONS. 


...SOUTHWEST/CALIFORNIA...

THE 12Z NAM SURFACE TEMPERATURE WAS INITIALIZED ABOUT 10 DEGREES
COOLER THAN OBSERVED NEAR PHOENIX ARIZONA. WINDS ARE LIGHT AND
VARIABLE WHICH IS GENERALLY DEPICTED IN THE 12Z NAM
INITIALIZATION. ATMOSPHERIC MOISTURE WAS ANALYZED WELL COMPARED
WITH OBSERVATIONS.


KONG/PETERSEN