NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1033 AM EDT MON JUL 23 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). ***

...COLORADO FRONT RANGE...

NO SIGNIFICANT INITIALIZATION ERRORS WERE NOTED WITH THE NAM IN
THIS REGION.

...NORTHERN UTAH...

THE NAM INITIALIZED SURFACE TEMPERATURES SOME 6 TO 10 DEGREES TOO
COOL...ESPECIALLY ALONG THE WEST FACE OF THE WASATCH...IN THE
UINTA BASIN AND IN THE SALT LAKE BASIN.

...INTERIOR VALLEYS OF CALIFORNIA...

ONCE AGAIN...THE NAM INITIALIZED SURFACE TEMPERATURES ARE 5 TO 10
DEGREES TOO COOL NEAR THE MOUNTAINS IN THESE REGIONS.  WIND SPEEDS
OF 10 KNOTS OR SO WERE OBSERVED IN THE SOUTHERN MOJAVE DESERT
WHERE THE NAM HAD WIND SPEEDS LESS THAN 5 KNOTS. 

...WESTERN AND SOUTHERN COLORADO BASIN...

THE NAM INITIALIZED SURFACE TEMPERATURES ARE 5 TO 8 DEGREES TOO
COOL...PARTICULARLY IN CLOSE PROXIMITY TO THE MOUNTAINS. THE NAM
DEPICTED SOME HIGHER RELATIVE HUMIDITY VALUES AND ISOLATED TO
SCATTERED SHOWERS IN THIS AREA...BUT IT APPEARS THAT THE MODEL
INITIALIZED THEM TOO FAR TO THE WEST.

...UPPER MIDWEST AND LOWER GREAT LAKES TO OHIO/TENNESSEE VALLEYS
AND NORTHERN GA...

NO SIGNIFICANT INITIALIZATION ERRORS WERE NOTED WITH THE NAM IN
THIS REGION.

...INTERIOR CAROLINAS TO MID ATLANTIC REGION AND SOUTHERN
PENNSYLVANIA...

THE NAM DEPICTED SCATTERED SHOWERS FROM CAROLINAS INTO SOUTHEAST
PENNSYLVANIA WHICH WAS NOT SUPPORTED BY SURFACE OBSERVATIONS OR
RADAR IMAGERY.  EXCEPT FOR THAT...NO OTHER SIGNIFICANT ERRORS WERE
NOTED WITH THE NAM IN THIS REGION.

...EASTERN TEXAS/SOUTHEAST OKLAHOMA/WESTERN AND SOUTHERN
MISSOURI...

NO SIGNIFICANT INITIALIZATION ERRORS WERE NOTED WITH THE NAM IN
THIS REGION. 

BANN