519  
FXUS10 KWNH 101830  
PMDHMD  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
229 PM EDT TUE OCT 10 2017  
 
VALID OCT 10/1200 UTC THRU OCT 14/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
...PLAINS TROUGH DEAMPLIFYING AND ACCELERATING TO THE NORTHEAST  
U.S. BY THURSDAY AND ACCOMPANYING WEAK SURFACE LOW IN THE UPPER  
MIDWEST / OHIO VALLEY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
FURTHER MODEL CONSOLIDATION OCCURRED WITH THE OVERNIGHT SOLUTIONS  
AS THE GEFS/CMCE AND OPERATIONAL GFS/UKMET/CMC ALL SHIFTED FURTHER  
NORTH WITH THE SURFACE WAVE WHILE ALSO BEING SLIGHTLY  
DEEPER/SLOWER YET...THE ECWMF AND ECENS MEMBERS REMAIN FURTHER  
NORTH AND WEST OVERALL. THE 12Z NAM/GFS SHIFTED TOWARD A SLIGHTLY  
DEEPER/SLOWER SOLUTIONS FURTHER CONSOLIDATING TO A COMPROMISE OF  
YESTERDAY'S ENSEMBLE SPREAD. AS SUCH THE 00Z ECMWF IS NOW ON THE  
OUTER FRINGE WITH LESS SUPPORT FROM OTHER MODEL SOLUTIONS. WHILE  
IT IS SMALL WOULD FAVOR THE TRENDING CONSENSUS PRESENTED BY THE  
12Z NAM/GFS AND 00Z UKMET/CMC. THE 00Z CMC SHOWS A WEAKER  
PRESENTATION THROUGH THE WAVE BUT TRACKS WELL OVERALL...ENOUGH TO  
SUGGEST ITS INCLUSION. A GENERAL MODEL BLEND WOULD SUFFICE AS THE  
SPREAD IS SIGNIFICANTLY REDUCED WITH A HOPE OF THE ECMWF/ECENS  
MEMBERS TO TREND TOWARD THE OTHER GROWING CONSENSUS OF THE  
GFS/NAM/UKMET/CMC. FOR NOW A NON-ECMWF SOLUTION IS PREFERRED BUT  
GIVEN THE SMALL DIFFERENCES CONFIDENCE IS FAIRLY HIGH (SLIGHTLY  
ABOVE AVERAGE).  
 
19Z UPDATE: THE 12Z ECMWF SHIFTED SLIGHTLY TOWARD THE GROWING  
CONSENSUS FURTHER SOUTH/EAST WITH THE SURFACE LOW AND WHILE IT  
REMAINS NORTHWEST OF THE GFS/NAM/CMC...IT IS PAIRED WITH THE 12Z  
UKMET THAT SHIFTED NORTHWEST AS WELL. OVERALL THESE DIFFERENCES  
ARE WELL WITHIN THE NOISE TO SUPPORT A GENERAL MODEL BLEND AT  
ABOVE AVERAGE CONFIDENCE.  
 
...UPPER TROUGH DIGGING SOUTHEAST INTO THE PACIFIC NORTHWEST ON  
TUESDAY WITH LEE CYCLOGENESIS IN THE VICINITY OF MONTANA WITH  
ATTENDANT COLD FRONT CROSSING THE NW REACHING NRN PLAINS ON  
THURSDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z ECMWF/CMC/UKMET BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE 12Z NAM CONTINUES TO A BIT MORE AGGRESSIVE WITH THE SHORTWAVE  
CROSSING BC INTO ALBERTA...EVEN TRENDING A BIT DEEPER/WOUND UP BU  
THURS WHICH ALSO MAKES IT A BIT FURTHER NORTH AND EAST OF THE  
GUIDANCE. IT IS GENERALLY SUPPORTED BY THE 00Z UKMET WHICH IS  
ALSO NORTH OF THE CONSENSUS BUT IS NOT AS DEEP/SUGGESTING A MORE  
OPEN WAVE. THE 12Z GFS REMAINS A BIT SOUTH AND MORE COMPACT THAN  
THE ECMWF/CMC BUT GENERALLY LIFTS IN TANDEM WITH THE ECMWF/CMC  
ACROSS CENTRAL CANADA FRIDAY. THE 00Z ECMWF/CMC ARE FAIRLY  
CENTRAL TO THE OVERALL ENSEMBLE SUITE INCLUDING THE 06Z GEFS MEAN  
WHICH MAKE IT A BIT FURTHER NORTH AND WEST OF THE GFS PRESENTING  
AN EARLIER OCCLUDED FRONT/TROWAL THAN THE MORE COMPACT GFS.  
OVERALL THE GFS IS CLOSE ENOUGH TO THE ECMWF/CMC/GEFS TO BE  
INCLUDED IN A BLEND TO HELP ENCAPSULATE THE SOUTHEAST/DEEPER  
POTENTIAL IT ALONG WITH A FEW GEFS MEMBERS PRESENTS. AS SUCH  
CONFIDENCE REMAINS SLIGHTLY ABOVE AVERAGE IN A 12Z GFS AND 00Z  
ECMWF/CMC BLEND.  
 
19Z UPDATE: THE 12Z UKMET TRENDED FURTHER SOUTH AND SLIGHTLY  
DEEPER MATCHING VERY CLOSE TO THE 12Z CMC WHICH SHOWED SMALL  
CHANGE. THE 12Z ECMWF ALSO REMAINED QUITE CONSISTENT IN THE  
MIDDLE PERHAPS TRENDING A BIT NORTH TOWARD FRI PLACING IT IN  
CLOSER PROXIMITY/EVOLUTION WITH THE UKMET/CMC. THIS PLACES THE  
12Z GFS A BIT MORE WOUND UP AND FURTHER SOUTH DISPLACED ABOUT AS  
MUCH AS THE NAM IS NORTH. THIS WOULD SUGGEST A BLEND THAT  
REPLACES THE 12Z GFS WITH THE 12Z UKMET MAY WORK OUT BEST  
PARTICULARLY NORTH OF THE US BORDER AS THE DIFFERENCES ARE VERY  
SMALL (MASS-WISE) ACROSS THE CONUS. AS SUCH A GENERAL MODEL BLEND  
OVER THE CONUS WILL SUFFICE OR A 12Z ECMWF/UKMET/CMC BLEND  
THROUGHOUT NORTH AMERICA HAS SLIGHTLY HIGHER CONFIDENCE.  
 
   
..SHORTWAVE DROPPING SOUTH TOWARD THE PAC NW LATE THURSDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
IN THE WAKE OF THE PRIOR SHORTWAVE...A MERIDIONAL JET ENTERS THE  
BACK SIDE OF THE TROF AND DESCENDS INTO THE PACIFIC NORTHWEST  
SUPPORTING FURTHER CARVING OUT THE LARGER SCALE TROF THURS. WHILE  
THERE ARE SOME SMALL DIFFERENCES INTERNALLY TO THE SHORTWAVE OVER  
THE PACIFIC NORTHWEST FRIDAY. THE 12Z NAM REMAINS THE DEEPEST AND  
SLIGHTLY FORWARD SOLUTIONS THOUGH THE 12Z GFS HAS TRENDED DEEPER  
AS WELL SUGGESTING SIMILAR OVERALL EVOLUTION. AS SUCH THE  
AGREEMENT IS STRONG FOR DAY 3 TO CONTINUE SUPPORT IN A GENERAL  
MODEL BLEND. GIVEN THE CONSISTENCY AS WELL...
CONFIDENCE IS ABOVE  
AVERAGE FOR THIS STRONG AGREEMENT SO FAR OUT IN TIME.  
 
19Z UPDATE: EXPECTED SMALL RUN TO RUN VARIATIONS OCCURRED WITH THE  
12Z VERSIONS OF THE ECMWF/UKMET/CMC AND GEFS MEAN BUT NOTHING  
SUBSTANTIAL TO BREAK FROM INITIAL PREFERENCE/CONFIDENCE OF GENERAL  
MODEL BLEND AT ABOVE AVERAGE CONFIDENCE.  
 
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
GALLINA  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page