NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1038 AM EDT MON AUG 01 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). ***


...INTERIOR VALLEYS OF CALIFORNIA/LOS ANGELES BASIN/DESERT
SOUTHWEST...

SURFACE TEMPERATURES ARE 5 TO 10 DEGREES WARMER THAN WHAT THE NAM
INITIALIZED OVER THE INTERIOR DESERTS OF SOUTHERN CALIFORNIA AND
SOUTHWEST ARIZONA. 


...FRONT RANGE OF COLORADO...

SURFACE TEMPERATURES ARE UP TO 10 DEGREES F WARMER THAN WHAT THE
NAM INITIALIZED IN VICINITY OF THE FRONT RANGE. THE ERRORS ARE
NOTED EXTENDING DENVER WEST OUT TOWARD BOULDER AND EXTENDING NORTH
INTO SOUTHEAST WYOMING.


...MIDWEST...

THE 12Z NAM IS SERIOUSLY UNDERDONE WITH THE INTENSITY AND COVERAGE
OF A STRONG MESOSCALE CONVECTIVE COMPLEX HITTING CENTRAL MINNESOTA
THIS MORNING ALONG WITH THE HANDLING OF ITS ASSOCIATED LARGE
CANOPY OF MID AND HIGH LEVEL CLOUDS SEEN STREAMING SOUTHEASTWARD
INTO WISCONSIN AND ILLINOIS.


...MID-ATLANTIC AND OHIO/TENNESSEE VALLEYS...

THE 12Z NAM DID NOT INITIALIZE ONGOING SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS NORTHEAST OHIO AND NORTHWEST
PENNSYLVANIA...AND HENCE IS NOT PROPERLY INITIALIZING THE AMOUNT
CLOUD COVER AND MOISTURE ASSOCIATED WITH THIS ACTIVITY.

ORRISON