NAM AIR QUALITY DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1053 AM EDT TUE JUN 19 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). ***

...INTERIOR VALLEYS OF CALIFORNIA/DESERT SOUTHWEST...

SURFACE TEMPERATURES OVER THE MOJAVE AND COLORADO DESERTS EAST OF
THE LOS ANGELES BASIN ARE AS MUCH AS 20 TO 25 DEGREES F WARMER
THAN INITIALIZED. SURFACE WIND SPEEDS OVER THESE DESERTS ARE AS
MUCH AS 10 TO 15 KTS STRONGER THAN INITIALIZED.

SURFACE TEMPERATURES HOWEVER ARE AS MUCH AS 5 DEGREES COOLER THAN
INITIALIZED OVER THE SACRAMENTO AND SAN JOAQUIN VALLEYS.


...NORTHERN FRONT RANGE OF COLORADO...

SURFACE TEMPERATURES ARE LOCALLY AS MUCH AS 10 DEGREES F WARMER
THAN INITIALIZED ALONG THE IMMEDIATE FRONT RANGE OF COLORADO.


...UPPER GREAT LAKES...

WIDESPREAD MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS ONGOING
OVER NORTHEASTERN WISCONSIN AND MOVING INTO UPPER AND NORTHERN
LOWER MICHIGAN ARE SIGNIFICANTLY UNDER-REPRESENTED IN THE NAM
INITIALIZATION FIELDS. SURFACE WINDS ACROSS CENTRAL AND NORTHEAST
WISCONSIN ARE AS MUCH AS 10 TO 20 KTS STRONGER THAN
INITIALIZED...WITH NORTHWEST WINDS OBSERVED VERSUS INITIALIZED
SOUTHERLY FLOW...AS A CONSEQUENCE OF THE STRONGER CONVECTION
IMPACTING THIS REGION.


...TENNESSEE VALLEY/OHIO VALLEY/MID-ATLANTIC/SOUTHEAST...

NO SIGNIFICANT INITIALIZATION ERRORS WERE NOTED.


ORRISON