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NAM Air Quality Diagnostic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1440Z Aug 21, 2012)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
1040 AM EDT TUE AUG 21 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). ***


...INTERMOUNTAIN WEST...
THE NAM WAS 5-10F TOO COOL ACROSS PORTIONS OF SOUTHWEST
IDAHO...NORTHERN UTAH...COLORADO...AND NORTHERN NEW MEXICO.  THE
NAM DID NOT INITIALIZE THE LOW IN SOUTHEAST COLORADO
CORRECTLY...SHOWING TOO LITTLE NORTHERLY COMPONENT BETWEEN LA
JUNTA AND LAMAR.  THE NAM DID NOT INITIALIZE THE SNAKE RIVER
VALLEY TROUGH CORRECTLY...AND DID NOT SHOW THE NORTHERLY WINDS
SEEN NEAR BELLEVUE IDAHO.

...CALIFORNIA/SOUTHERN NEVADA/ARIZONA...
THE NAM WAS 5-15F TOO COOL ACROSS SOUTHERN ARIZONA...SOUTHERN
NEVADA...AS WELL AS SOUTH-CENTRAL AND SOUTHEAST CALIFORNIA.  WINDS
WERE 5-10 KNOTS TOO WEAK IN THE NAM BETWEEN MOJAVE AND BARSTOW
CALIFORNIA...AS WELL AS THE LOWER COLORADO RIVER VALLEY.  THE NAM
PRECIPITATION ADVERTISED ACROSS ARIZONA AND SOUTHERN CALIFORNIA
HAS NOT OCCURRED.

...SOUTHERN PLAINS/MID-SOUTH...
THE NAM WAS 5F TOO COOL NEAR JUNCTION TEXAS.  NAM WINDS WERE 5-10
KNOTS TOO LIGHT IN CENTRAL AND WESTERN TEXAS.  PRECIPITATION NEAR
THE OKLAHOMA/TEXAS PANHANDLE BORDER WAS MUCH HEAVIER THAN THE NAM
ADVERTISED.

...OHIO VALLEY/MID-ATLANTIC STATES...
THE SCATTERED SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN ILLINOIS
AND SOUTHERN INDIANA WERE NOT INDICATED BY THE NAM.

ROTH