NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1025 AM EDT FRI JUL 13 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). ***


...MIDWEST TO THE MID-ATLANTIC AND NORTHEAST...

THE 12Z NAM HAS NOT INITIALIZED ONGOING CONVECTION ACROSS
MINNESOTA AND WISCONSIN THIS MORNING. AS A RESULT...INITIALIZED
RELATIVE HUMIDITY VALUES IN THE BOUNDARY LAYER AND MID-LEVELS MAY
BE TOO LOW. CONVECTION FARTHER SOUTH ACROSS IOWA/MISSOURI/KANSAS
DOES APPEAR TO HAVE BEEN INITIALIZED WELL BY THE 12Z NAM.


...VALLEYS OF THE INTERMOUNTAIN WEST...

SURFACE TEMPERATURES WERE OBSERVED TO BE 5 TO 7 DEGREES WARMER
THAN INITIALIZED BY THE 12Z NAM IN THE COLUMBIA RIVER VALLEY AS
WELL AS NEAR SALT LAKE.


...SOUTHERN PLAINS...
...SOUTHWESTERN U.S...
...COLORADO...

NO SIGNIFICANT INITIALIZATION ERRORS WERE NOTED WITH THE 12Z NAM
IN THESE REGIONS.


RYAN