NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1016 AM EDT TUE JUL 26 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...
...DESERT SOUTHWEST...

THE NAM SURFACE TEMPERATURES ARE INITIALIZED 5 TO 10 DEGREES F
LOWER THAN OBSERVED OVER PORTIONS OF THE CENTRAL CALIFORNIA
VALLEY... AND 10 TO 20 DEGREES F TOO LOW OVER SOME AREAS IN
SOUTH-CENTRAL AND SOUTHERN INTERIOR CALIFORNIA.  NAM TEMPERATURES
ARE ALSO 10 TO 15 DEGREES TOO LOW ALONG THE EXTREME SOUTHERN PART
OF THE CALIFORNIA/NEVADA BORDER.  MEANWHILE OVER EXTREME SOUTHERN
NEVADA OBSERVED WINDS ARE FROM THE SOUTH AT 15 KTS VERSUS THE NAM
ANALYSIS THAT SHOWS WINDS FROM THE SOUTHEAST AT 5 KTS.  OBSERVED
WINDS OVER THE SOUTHERN HALF OF INTERIOR CALIFORNIA ALSO DEVIATE
IN SPEED AND/OR DIRECTION FROM THE NAM ANALYSIS OF WEST/NORTHWEST
AT 5 KTS BUT WITH ERRORS DIFFERING BY INDIVIDUAL LOCATION.  LATEST
RADAR SUGGESTS THE BEGINNING OF THE NAM FCST MAY BE OVERDONE WITH
COVERAGE OF LIGHT RAINFALL OVER SOUTHEASTERN CALIFORNIA.


...FRONT RANGE OF COLORADO...

THE NAM DISPLAYS NO SIGNIFICANT INITIALIZATION ERRORS.


...OHIO VALLEY/TENNESSEE VALLEY...
...MISSISSIPPI VALLEY...
...EASTERN/SOUTH-CENTRAL PLAINS...

THE NAM DISPLAYS NO SIGNIFICANT INITIALIZATION ERRORS.


...MID ATLANTIC...

THE NAM DISPLAYS NO SIGNIFICANT INITIALIZATION ERRORS.


RAUSCH