HPC Model Diagnostic Discussion

Hydrometeorological Prediction Center

MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
238 AM EDT TUE MAY 22 2012

VALID MAY 22/0000 UTC THRU MAY 25/1200 UTC

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


FINAL 00Z MODEL EVALUATION INCLUDING THE ECMWF


MODEL INITIALIZATION ERRORS ARE INDICATED UNDER THE RELEVANT
SYSTEM HEADING.


...NERN PAC ENERGY DROPPING INTO THE WEST BY THU-FRI...

PREFERENCE:  GEFS MEAN/ECMWF COMPROMISE 2/3 TOWARD THE ECMWF
CONFIDENCE:  AVERAGE TO ABOVE AVERAGE

GUIDANCE AGREES FAIRLY WELL WITH LARGE SCALE EVOLUTION BUT SOME
DETAIL DIFFS ARE EVIDENT.  BY F84 EARLY FRI THE NAM EXTENDS THE
OVERALL TROF SLIGHTLY WWD/SWWD VERSUS MOST OTHER SOLNS ASIDE FROM
THE CANADIAN GLBL.  THE GFS CLOSED LOW CENTER IS NOT FAR FROM
CONSENSUS BY F84 THOUGH THE MODEL HOLDS BACK LINGERING UPSTREAM
ENERGY A BIT COMPARED TO THE MAJORITY OF GUIDANCE... AND IS
WEAKEST WITH THE UPSTREAM RIDGE... LEADING TO A SLIGHTLY FLAT
HANDLING OF FLOW ON THE SWRN SIDE OF THE TROF.  THE
ECMWF/UKMET/CANADIAN GLBL ARE ALL A LITTLE DEEPER THAN THE NAM/GFS
BY F84 WITH THE CLOSED LOW AND TRACK THE CENTER WWD OF THE
GFS/GEFS MEAN.  THE 12Z ECMWF MEAN IS MORE SIMILAR TO THE GEFS
MEAN SO UP TO 1/3 WEIGHTING OF THE LATTER WITH THE ECMWF IS
MERITED. 


...ERN PAC ENERGY INITIALLY MOVING INTO THE NORTHWEST...
...SYSTEM TRACKING NEWD FROM THE PLAINS THU ONWARD...

PREFERENCE:  12Z/00Z ECMWF COMPROMISE
CONFIDENCE:  BELOW AVERAGE

THE PRIMARY DIFFS ARISE AS MID LVL ENERGY AND SFC LOW PRESSURE
TRACK NEWD FROM THE PLAINS WED NIGHT ONWARD.  THE NAM IS ON THE
WEAK AND PROGRESSIVE SIDE OF THE SPECTRUM WITH THE OVERALL SYSTEM.
 THE GFS IS MORE DEVELOPED THAN THE NAM AND STRENGTH/TIMING ARE
SIMILAR TO THE 21Z SREF MEAN.  THE UKMET/CANADIAN GLBL/18Z GEFS
MEAN AND 12Z ECMWF/ECMWF MEAN ARE ALL SLOWER TO VARYING DEGREES. 
THE UKMET WRAPS THE SFC LOW FARTHEST WWD BY LATE THU-FRI AND THIS
IS SOMETIMES A BIAS OF THE MODEL SO PREFER TO LEAN AWAY FROM ITS
SOLN.  IN ADDITION THE GEFS MEAN/ECMWF HAVE BOTH TRENDED FASTER IN
THEIR 00Z RUNS BY THU NIGHT.  RECENT RUNS OF SOME GUIDANCE HAVE
BEEN ERRATIC WITH THIS SYSTEM... INCL THE ECMWF TRENDING FASTER
FOR TWO RUNS NOW AFTER YDAYS 00Z RUN WAS A SLOW EXTREME... AND GFS
RUNS DIFFERING SIGNIFICANTLY IN STRENGTH AND TO SOME EXTENT
TIMING.  THUS PREFER AN INTERMEDIATE SOLN THAT IS BEST REPRESENTED
BY A COMPROMISE BETWEEN THE 00Z ECMWF AND SOMEWHAT SLOWER 12Z
ECMWF.


...DIFFUSE TROF DRIFTING OVER THE EAST TUE ONWARD...

PREFERENCE:  GFS/ECMWF/UKMET/CMC BLEND INTO EARLY THU... MINUS THE
GFS THEREAFTER
CONFIDENCE:  AVERAGE TO SLIGHTLY ABOVE AVERAGE

FROM LATE WED ONWARD THE NAM IS MORE PROGRESSIVE THAN MOST SOLNS
WITH A MAJORITY OF THE MID LVL ENERGY THAT REACHES THE MID ATLC. 
THE GFS IS CLOSER TO CONSENSUS THAN THE NAM FOR THIS PART OF THE
FCST THOUGH THE GFS MAY ALSO BECOME A LITTLE FAST BY LATE THU-FRI
DUE TO UPSTREAM PROGRESSION.  OVERALL PREFER A
GFS/ECMWF/UKMET/CANADIAN GLBL BLEND INTO EARLY THU... REMOVING THE
GFS FROM THE BLEND THEREAFTER AS IT TRENDS FASTER THAN THE OTHER
SOLNS.


...FLOW FROM THE NWRN CARIBBEAN/GULF NEWD...

PREFERENCE:  GFS/ECMWF BLEND
CONFIDENCE:  AVERAGE

BY THU INTO FRI THE NAM BECOMES A STRONG EXTREME WITH SHRTWV
ENERGY WHICH THE MODEL BRINGS NEWD FROM THE GULF/FL TO THE NC/SC
COAST.  THIS IS ASSOC WITH A CONCENTRATED QPF MAXIMUM THAT TRACKS
FROM THE SRN FL PENINSULA TO OFF THE NC/SC COAST LATE WED ONWARD. 
ALSO 00Z GLOBAL MODEL CONSENSUS KEEPS SFC WAVINESS FARTHER OFF THE
SERN COAST THAN THE NAM BY THU NIGHT.  A GFS/ECMWF BLEND APPEARS
REASONABLE.   


...SYSTEM TRACKING OFF THE NERN COAST TUE...

PREFERENCE:  NAM/GFS/UKMET COMPROMISE
CONFIDENCE:  ABOVE AVERAGE

GUIDANCE IS CONVERGING WITH RESPECT TO THE TRACK/TIMING OF THIS
FEATURE... THOUGH THE 00Z ECMWF HAS ADJUSTED A BIT TO THE WRN SIDE
OF THE GUIDANCE SPREAD.  UNTIL MORE SOLNS TREND THAT WAY WILL
RECOMMEND A NAM/GFS/UKMET COMPROMISE.


...TROPICAL DEPRESSION ALBERTO...

BASED ON THE NAM BNDRY LYR WIND ANALYSIS... THE MODEL PLACES THE
CENTER OF ALBERTO ABOUT 40-50 NM NNW OF OBSERVED POSN.  THE ECMWF
STARTS OUT ABOUT 50 NM WSW OF OBSERVED POSN.  ERROR IN THE GFS
ANALYSIS IS NEGLIGIBLE AND THE MODEL STAYS FAIRLY CLOSE TO THE
TRACK DEFINED BY THE 03Z NHC ADVISORY THRU AT LEAST 24-36 HRS. 
PLEASE REFER TO THE LATEST NHC ADVISORY FOR FURTHER INFO REGARDING
T.D. ALBERTO.


...MODEL TREND GRAPHICS AT
WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
...500 MB FORECASTS AT WWW.HPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

RAUSCH