NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1020 AM EDT THU JUN 02 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). ***

...MIDWEST/OHIO VALLEY...

THE 12Z NAM IS SIGNIFICANTLY UNDER DOING THE INTENSITY AND
COVERAGE OF AN ONGOING MESOSCALE CONVECTIVE COMPLEX INVOLVING
SOUTHEAST IOWA...EASTERN MISSOURI AND WESTERN ILLINOIS...ALONG
WITH THE RESULTING CLOUD COVER. THIS LARGER AND MORE ORGANIZED
COVERAGE OF SHOWER AND THUNDERSTORM ACTIVITY IS ALSO PRODUCING A
FAIRLY WELL-DEFINED OUTFLOW BOUNDARY WITH RESULTING WESTERLY AND
NORTHWESTERLY WINDS OF 10 TO 20 KTS ACROSS EASTERN MISSOURI AND
INTO WESTERN AND CENTRAL ILLINOIS. THIS IS VERSUS AN INITIALIZED
EAST-SOUTHEAST WIND OF 5 TO 10 KTS.


...TENNESSEE VALLEY...

NO SIGNIFICANT INITIALIZATION ERRORS WERE NOTED.


...SOUTHEAST...

THE NAM INITIALIZED SURFACE TEMPERATURES AS MUCH AS 5 TO 9 DEGREES
F WARMER THAN WHAT WAS OBSERVED OVER PORTIONS OF WESTERN GEORGIA. 


...EASTERN TEXAS/ARKANSAS/LOUISIANA...

THE NAM INITIALIZED SURFACE TEMPERATURES AS MUCH AS 5 TO 7 DEGREES
F WARMER THAN WHAT WAS OBSERVED OVER PORTIONS OF EASTERN AND
NORTHEASTERN TEXAS.


ORRISON