NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1021 AM EDT TUE JUN 14 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). ***


...LOWER OHIO VALLEY...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.

...SOUTHEAST/GULF COAST...

NO SIGNIFICANT INITIALIZATION ERRORS ARE NOTED.

...LOWER/MID-MISSISSIPPI VALLEYS...
 12Z NAM BOUNDARY LAYER WIND SPEED WAS OVERDONE WITH EASTERLIES
OVER IA/IL BY 10-15KTS AND IN GENERAL THE WIND DIRECTION IN
VICINITY OF THE DECAYING-MCS AND ASSOCIATED CLUSTER OF SHOWERS AND
THUNDERSTORMS OVER MISSOURI/ILLINOIS. THE PRECIPITABLE AND
RELATIVE HUMIDITY FIELDS ARE IN GENERALLY GOOD SHAPE ALTHOUGH
CONVECTION WAS PRESENT FOR THE INITIALIZATION.

...DESERT SOUTHWEST/CALIFORNIA/NEVADA...

OBSERVED PRECIPITABLE WATERS VALUES OVER THE SACRAMENTO VALLEY
WERE SLIGHTLY ABOVE THE 12Z NAM INITIALIZATION VALUES. AND SURFACE
TEMPERATURES WERE A GOOD 5-15F LOWER THAN INITIALIZED OVER
INTERIOR PORTIONS OF NORTHERN AND CENTRAL NEVADA.

VOJTESAK