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Model Diagnostics Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0609Z Nov 26, 2014)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
109 AM EST WED NOV 26 2014

VALID NOV 26/0000 UTC THRU NOV 29/1200 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

00Z NAM/GFS EVALUATION INCLUDING THE UKMET/CANADIAN/ECMWF AND
PREFERENCES

...LOW PRESSURE OVER THE NORTHERN PLAINS...

PREFERENCE: NAM 
CONFIDENCE: ABOVE AVERAGE

THE NAM IS SLOWER THAN THE GFS AND ECMWF CROSSING THE PLAINS AND
APPROACHING THE APPALACHIANS.  GIVEN THAT NAM INITIALIZES SOME MID
AND UPPER LEVEL ASPECTS OF THE ACCOMPANYING SHORTWAVE TROUGH
BETTER THAN THE GFS...THE RECOMMENDATION IS FOR THE NAM.

...LOW PRESSURE FORMING ALONG THE EAST COAST...

PREFERENCE: HALFWAY BETWEEN THE NAM AND ECMWF FOR TRACK AND DEPTH
CONFIDENCE: ABOVE AVERAGE

THE NAM AND GFS HAVE TRENDED SLOWER WITH THE LOW MOVING UP THE
EAST COAST WHICH IS A REVERSAL FROM PREVIOUS DAYS...WHICH NOW
LEAVES THE 21Z SREF MEAN NEAR THE FAST AND NORTHERN EDGE OF THE
GUIDANCE.  THE NAM ALSO INITIALIZES MID AND UPPER LEVEL ASPECTS OF
AN INFLUENTIAL SHORTWAVE TROUGH OVER THE PLAINS BETTER THAN THE
GFS.  GIVEN THAT BOTH THE NAM AND GFS HAVE TRENDED SLOWER AND THAT
THE NAM IS PREFERRED UPSTREAM...THE NAM'S SLOWER SPEED UP THE EAST
COAST VERSUS THE GFS IS PREFERRED.  THE 12Z ECMWF AND 12Z ECMWF
ENSEMBLE MEAN AS WELL AS THE 12Z UKMET CLUSTER WELL WITH THE NAM
AND COULD BE COMBINED WITH THE NAM TO ADDRESS ANY LINGERING
UNCERTAINTIES.  REGARDING 2M TEMPERATURES...THE 21Z SREF MEAN LIES
THE COLD EDGE OF THE GUIDANCE AND IS DISREGARDED PER ITS FAST LOW
SPEED AND OCCASIONAL COLD BIAS.  OF THE REMAINING SOLUTIONS...THE
NAM IS COLDER THAN THE GFS BUT ONLY SLIGHTLY...WITH AN
INTERMEDIATE TEMPERATURE LIKELY THE BEST.

...SHORTWAVE TROUGH INFLUENCING THE PACIFIC NORTHWEST AND NORTHERN
ROCKIES THU/FRI...

PREFERENCE: BEFORE 12Z FRI...NAM OR ECMWF
CONFIDENCE: AFTER 12Z FRI...ECMWF

THE NAM AND ECMWF SHOW STRONG AGREEMENT WITH EACH OTHER AND
CLUSTER WELL WITH THE REMAINING SOLUTIONS AND THE ENSEMBLE MEANS
EXCEPT THE GFS WHICH IS NEARLY A FAST OUTLIER WITH THE NORTHERN
STREAM ACROSS CANADA RESULTING IN A VERY DIFFERENT FRONTAL
DEPICTION OVER THE DAKOTAS BY EARLY SATURDAY.  AFTER 12Z
FRIDAY...THE GFS REMAINS TOO FAST OVER CANADA AND THE NAM TOO
PROGRESSIVE WITH THE SOUTHERN STREAM ENTERING THE WEST COAST. 
MEANWHILE...THE ECMWF LIES NEAR THE MIDDLE OF THE SOLUTION
ENVELOPE AND HAS THE STRONGEST SUPPORT FROM THE ENSEMBLE MEANS. 
THEREFORE...RECOMMEND THE ECMWF FROM FRIDAY ONWARD.

www.wpc.ncep.noaa.gov/html/model2.shtml...
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

JAMES