000
FXUS10 KWNH 061824
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
222 PM EDT MON JUL 06 2009

VALID JUL 06/1200 UTC THRU JUL 10/0000 UTC

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

12Z NAM/GFS/CANADIAN/UKMET/ECMWF EVALUATION AND PREFERENCES

ANY INITIALIZATION ERRORS WITH THE NAM/GFS DO NOT APPEAR TO
NEGATIVELY IMPACT THEIR SHORT RANGE FORECASTS.

TROUGHING MOVING THROUGH THE NORTHWEST AND NORTHERN PLAINS BY
THURSDAY...
THE NAM HAS SHOWN REASONABLE CONTINUITY WITH THIS SYSTEM OVER ITS
PAST DAY OF RUNS.  THE GFS HAS TRENDED STRONGER WITH THE FIRST
PIECE OF ENERGY EJECTING FROM THE TROUGH INTO CANADA WHILE
TRENDING SOUTHEAST WITH THE SECOND PIECE OF ENERGY NEAR THE
PACIFIC NORTHWEST ON THURSDAY.  THE ECMWF HAS TRENDED SLIGHTLY
SLOWER WITH THE FIRST SYSTEM AND WAVERED AROUND A COMMON SOLUTION
WITH THE SYSTEM NEAR THE PACIFIC NORTHWEST ON THURSDAY DURING ITS
PAST COUPLE DAYS OF RUNS.  WITH THE FIRST PIECE OF ENERGY...THE
NAM IS A WEAK OUTLIER WHEN COMPARED TO THE REST OF THE
GUIDANCE...WHICH EXPLAINS ITS LACK OF SURFACE CYCLONE ACROSS
SOUTHERN CANADA THURSDAY.  WITH THE 00Z MULTI-MODEL ENSEMBLE
SPREAD ENCOMPASSING THE NON-NAM GUIDANCE...A COMPROMISE BETWEEN
THE 06Z GFS/00Z CANADIAN/00Z UKMET/00Z ECMWF/06Z GEFS MEAN IS
ADVISABLE...WHICH IS CENTERED AROUND THE 00Z OR 12Z UKMET LOW
PLACEMENT.  FOR FRONTAL TIMING...THE MORE NORTHERLY 12Z NAM/00Z
ECMWF/12Z UKMET APPEAR BEST.  WITH THE SECOND PIECE OF ENERGY
MOVING INTO THE PACIFIC NORTHWEST...THE 06Z GFS/00Z CANADIAN/00Z
UKMET/00Z ECMWF ENSEMBLE MEAN ARE MORE WESTERLY THAN THE 12Z
GFS/00Z ECMWF/06Z GEFS MEAN SOLUTIONS.  PER THE RECENT SHIFTS MADE
IN THE GFS AND ECMWF...WILL PREFER A COMPROMISE BETWEEN THE 12Z
ECMWF AND 12Z GFS.

TROUGHING ACROSS THE NORTHEAST WEDNESDAY...
THE NAM HAS TRENDED STRONGER/SLOWER WITH THIS SYSTEM OVER ITS PAST
DAY OF RUNS...REVERSING ITS TREND FROM THIS TIME YESTERDAY.  THE
ECMWF IS ON THE SLOW SIDE OF ITS PAST COUPLE DAYS OF RUNS WITH
THIS SYSTEMS PROGRESSION.  THE GFS HAS TRENDED QUICKER WITH THIS
SYSTEM OVER ITS PAST DAY OF RUNS.  WHEN COMPARING THE
GUIDANCE...THE 06Z/12Z GFS ARE QUICK OUTLIERS WITH THIS SYSTEMS
PROGRESSION FROM TUESDAY NIGHT ONWARD.  SINCE THE TREND IS IN THE
OTHER DIRECTION...WILL TOSS OUT THE 06Z GFS.  THE 12Z NAM DOES
APPEAR TO BE TOO DEEP WITH THIS SYSTEM FROM TUESDAY ONWARD.  WILL
FAVOR THE SLOWER/WEAKER CONSENSUS HERE...WHICH INCLUDES THE 00Z
AND 12Z CANADIAN/00Z AND 12Z ECMWF/06Z GEFS MEAN/00Z ECMWF
ENSEMBLE MEAN.

BREAK IN THE SUBTROPICAL RIDGE ACROSS THE CENTRAL GULF COAST...
THE NAM HAS TRENDED SLIGHTLY WEAKER WITH ITS TROUGHING IN THIS
REGION OVER ITS PAST DAY OF RUNS.  BY LATE THURSDAY...THE ECMWF
TRENDS STRONGER WITH THE MID-LEVEL TROUGHING OVER ITS PAST COUPLE
DAYS OF RUNS.  THE GFS HAS TRENDED SLIGHTLY QUICKER/WEAKER WITH
THIS FEATURE OVER ITS PAST DAY OF RUNS.  WHEN COMPARING THE
GUIDANCE...THE 06Z GFS IS A WEAK OUTLIER WITH THIS FEATURE WHILE
THE NAM/ECMWF ARE TRENDING TOGETHER...AND ARE GENERALLY SUPPORTED
BY THE 00Z CANADIAN/00Z UKMET.  WILL FAVOR A 12Z NAM/00Z AND 12Z
ECMWF COMPROMISE WITH THIS FEATURE THROUGH THURSDAY.

...MODEL TREND GRAPHICS AT
WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...

...500 MB FORECASTS AT
WWW.HPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

ROTH
$$