Prognostic Meteorological Discussion
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000
FXUS10 KWNH 261914
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
213 PM EST WED NOV 26 2014

VALID NOV 26/1200 UTC THRU NOV 30/0000 UTC

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

12Z MODEL EVALUATION INCLUDING THE CANADIAN/UKMET/ECMWF

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

WITH LITTLE RUN TO RUN CHANGE BY EITHER THE NCEP OR NON NCEP
MODELS IN THE 12Z MODEL PRODUCTION CYCLES...AND THE MODELS
CLUSTERING WELL...FEEL THAT EQUAL USE OF THE GUIDANCE WOULD WORK
FINE.

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

PREFERENCE: HALFWAY BETWEEN THE NAM AND GFS...ESSENTIALLY A MODEL
CONSENSUS
CONFIDENCE: AVERAGE

BOTH THE NAM AND GFS INITIALIZED THE MID LEVEL HEIGHTS ABOUT 25 TO
30 METERS LOWER THAN OBSERVED AT KIAD...WITH 20 METER HEIGHT
DIFFERENCES EXTENDING OVER TO WALLOPS ISLAND AND DOWN TO MOREHEAD
CITY AND BACK TOWARDS JACKSONVILLE.  THERE WERE SIMILAR
DIFFERENCES BETWEEN THE RAOBS AND MODEL INITIALIZATION FROM BOTH
THE NAM AND GFS OVER BERMUDA AS WELL.

THE 12Z GUIDANCE IN GENERAL HAD GOOD CONTINUITY...WITH THE ECMWF
MAINTAINING ITS STRONGER SOLN FROM 26/00Z RUN.  THAT LEFT THE
NAM/GFS ROUGHLY IN THE MIDDLE OF THE SPREAD. A SOLN SOMEWHERE
BETWEEN THE SPEED OF THE WAVE AS SHOWN BY THE GFS/NAM AND A BIT
TOWARDS THE AMPLITUDE OF THE ECMWF LOOKS TO HAVE THE BEST SUPPORT
FROM THE ENSEMBLES.

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

PREFERENCE: 26/12Z ECMWF
CONFIDENCE: ABOVE AVERAGE

GIVEN GOOD RUN TO RUN CONTINUITY...THE 12Z NAM MAINTAINED AN
ALLIANCE IT FORMED WITH THE 12Z ECMWF.  EARLY ON IN THE
FORECAST...THERE IS GENERAL AGREEMENT WITH THE GFS AND CMC/UKMET.
HOWEVER...AFTER 12Z ON FRIDAY...THE NAM BECAME TOO PROGRESSIVE
WITH THE SOUTHERN STREAM ENTERING THE WEST COAST. CONSIDERING THAT
THE 26/12Z ECMWF STILL LIES NEAR THE MIDDLE OF THE SOLUTION
ENVELOPE AND HAS THE STRONGEST SUPPORT FROM THE ENSEMBLE
MEANS...THE 12Z ECMWF WAS THE MOST STRONGLY PREFERRED OF THE
OPERATIONAL MODELS.

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

BANN

$$




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