NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1024 AM EDT WED JUL 25 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...
...NORTHERN SIERRA NEVADA RANGE...
...DESERT SOUTHWEST...

THE NAM INITIALIZES TEMPERATURES 5 TO 20 F LOWER THAN OBSERVED
OVER SOUTHERN PORTIONS OF INTERIOR CALIFORNIA AND EXTREME SOUTHERN
NEVADA.  ALSO SOME LOCATIONS OVER INTERIOR SOUTHERN CALIFORNIA
REPORT WINDS FROM THE WEST AT 10 TO 15 KTS VERSUS THE NAM ANALYSIS
THAT INDICATES WIND SPEEDS OF ONLY AROUND 5 KTS.


...NORTHERN UTAH...
...CENTRAL COLORADO...

THE NAM INITIALIZES SURFACE TEMPERATURES 5 TO 10 F LOWER THAN
OBSERVED JUST EAST OF THE GREAT SALT LAKE.


...EAST-CENTRAL/SOUTH-CENTRAL PLAINS...
...LOWER MISSISSIPPI VALLEY...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.


...MID/UPPER MISSISSIPPI VALLEY...
...OHIO VALLEY...
...GREAT LAKES...

SOME LOCATIONS OVER SOUTHWESTERN WISCONSIN REPORT WINDS FROM THE
EAST INSTEAD OF SOUTH-SOUTHEAST AS IN THE NAM ANALYSIS... THOUGH
ANALYZED SPEEDS OF 5 TO 10 KTS ARE REASONABLE.  COMPARING RADAR TO
THE FIRST 3-HR NAM FCST SUGGESTS THE MODEL MAY BE
UNDER-REPRESENTING CONVECTION INITIALLY OVER SOUTHEASTERN
WISCONSIN AND SOUTHERN LAKE MICHIGAN.  ON THE OTHER HAND THERE IS
NO OBSERVATIONAL SUPPORT FOR LIGHT RAINFALL WHICH THE NAM PLACES
OVER SOUTH-CENTRAL INTO EASTERN ILLINOIS.


...TENNESSEE VALLEY...
...SOUTHEAST...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.


...MID ATLANTIC...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.


RAUSCH