NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
1017 AM EDT WED AUG 22 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). ***


...CALIFORNIA/SOUTHERN NEVADA/ARIZONA...

THE NAM WAS 5-15 F TOO COOL ACROSS VALLEY LOCATIONS NEAR THE
NEVADA-CALIFORNIA BORDER/SIERRA NEVADA RANGE.  THE 12Z NAM
PRECIPITABLE WATER WAS ABOUT 0.2 INCHES TOO LOW IN THE 12Z
SOUNDING AT NKX/MIRAMAR NAVAL AIR STATION IN SOUTHERN CA...AND AT
TUSCON AZ.

NAM ESTIMATED 10M WINDS WERE 5-10 KNOTS TOO WEAK IN THE NAM IN
VALLEY LOCATIONS OF SOUTHERN NV.  OBSERVED RAINFALL IS OCCURRING
OVER A LARGER AREA AND WITH HEAVIER TOTALS THAN THE 12Z NAM
INDICATES NEAR THE AZ/NV/UT BORDER REGION.

...SOUTHERN ID/NORTHERN UT/COLORADO...

THE NAM WAS 5-10 F TOO COOL ACROSS VALLEY LOCATIONS OF SOUTHERN
IDAHO...NORTHERN UTAH...COLORADO.

...SOUTHERN PLAINS/SOUTHEAST...

THE NAM WAS 5-9 F TOO COOL NEAR HARRISON AR AND TULSA OK.  NAM
WINDS WERE 5-10 KNOTS TOO LIGHT IN WESTERN TEXAS/TX PANHANDLE. 
SHOWER COVERAGE OVER CENTRAL TX WAS GREATER THAN SHOWN IN THE NAM
12-15Z FORECAST.

...OHIO VALLEY/MID-ATLANTIC STATES...

THE NAM 12Z TEMP AT INDIANAPOLIS IN WAS ABOUT 4 DEGREES WARMER
THAN THE NAM INITIAL ANALYSIS INDICATES.


PETERSEN