NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1024 AM EDT FRI AUG 03 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...

THE NAM INITIALIZED TEMPERATURES ON THE ORDER OF 10 TO 15 DEGREES
TOO LOW IN THE SOUTHERN VALLEYS...ESPECIALLY NEAR MOJAVE AND PALM
SPRINGS.

...NORTHERN TENNESSEE VALLEY...

THE RAINFALL ASSOCIATED WITH THE DECAYING MCS WAS NOT INITIALIZED
WELL BY THE NAM ACROSS CENTRAL AND EASTERN TENNESSEE...AS THE
MODEL WAS TOO LIGHT WITH THE RAINFALL COMPARED TO THE OBSERVED
RADAR IMAGERY AND PRECIPITATION ESTIMATES.

HURLEY