037  
FXUS10 KWNH 091620  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1119 AM EST THU NOV 09 2017  
 
VALID NOV 09/1200 UTC THRU NOV 13/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH LATEST MODEL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..SHORTWAVE CROSSING THE SOUTHEAST THROUGH TONIGHT
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS ARE IN VERY GOOD AGREEMENT WITH THEIR MASS FIELDS  
ASSOCIATED WITH THIS SYSTEM...SO A GENERAL MODEL BLEND WILL BE  
PREFERRED.  
 
...DEEP CYCLONE OFFSHORE OF THE PACIFIC NORTHWEST OPENING INTO A  
TROUGH OVER THE NORTHWEST BY FRIDAY...  
...TROUGH MOVING EAST ACROSS THE NORTHERN PLAINS/MIDWEST AND GREAT  
LAKES THIS WEEKEND...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
AN UPPER LOW APPROACHING THE PACIFIC NORTHWEST WILL BEGIN MOVING  
INLAND TONIGHT AND INTO THE INTERIOR OF THE NORTHWEST ON FRIDAY  
WHILE ALSO STARTING TO OPEN UP INTO A TROUGH. A PORTION OF THE  
ENERGY WILL BREAK AWAY AND STREAM DOWNWIND ACROSS THE FAR NORTHERN  
PLAINS/UPPER MIDWEST NEAR THE CANADIAN BORDER WHILE GRADUALLY  
DAMPENING OUT BY THE END OF THE PERIOD. A SLOWER PIECE OF THE  
TROUGH THOUGH WILL HANG BACK FOR A LITTLE LONGER OVER THE NORTHERN  
INTERMOUNTAIN REGION AND THEN EJECT OUT ACROSS THE PLAINS AND  
BECOME THE MORE DOMINANT SHORTWAVE OVER THE MIDWEST AND THE GREAT  
LAKES BY SUNDAY. MODEL MASS FIELD SPREAD IS RATHER MINIMAL AS THIS  
ENERGY TRAVERSES THE INTERMOUNTAIN WEST. HOWEVER THE 12Z NAM IS A  
LITTLE SLOWER AND DEEPER WITH THE INITIAL SURGE OF ENERGY ACROSS  
THE FAR NORTHERN TIER STATES THROUGH SATURDAY. THE 12Z NAM ALSO  
TENDS TO BECOME A BIT SLOWER AND DEEPER WITH THE ARRIVAL OF THE  
ADDITIONAL SHORTWAVE TROUGHING ACROSS THE MIDWEST AND GREAT LAKES  
BY SUNDAY. THE 00Z UKMET ALSO APPEARS TO BE TOO SLOW AS WELL.  
BETTER MODEL CLUSTERING AND ENSEMBLE SUPPORT AGAIN FAVORS A  
SOLUTION TOWARD A BLEND OF THE 12Z GFS AND 00Z ECMWF AND THIS WILL  
BE THE PREFERENCE.  
 
   
..AMPLIFYING NORTHERN STREAM TROUGH/CLOSED LOW NEAR GREAT LAKES
 
   
..COLD FRONT CROSSING THE NORTHERN TIER STATES THROUGH FRIDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS SHOW VERY GOOD AGREEMENT WITH THEIR MASS FIELDS  
ASSOCIATED WITH THIS SYSTEM...WITH SIMILAR TIMING OF THE  
FRONT...PLACEMENT OF THE TROUGH...INTENSITY AND PLACEMENT OF THE  
SURFACE LOW...AND THE DETAILS OF THE COLD SURFACE HIGH BUILDING  
ACROSS THE EASTERN U.S. IN THE WAKE OF THE EXITING LOW AND FRONT.  
 
   
..UPPER TROUGH OFFSHORE OF THE PACIFIC NORTHWEST THIS WEEKEND
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
AS THE TROUGH DROPS SOUTH OVER THE NORTHEAST PACIFIC...DIFFERENCES  
BEGIN TO EMERGE PRIMARILY RELATED TO TIMING AND PRECISE PLACEMENT  
OF THE MID-UPPER LEVEL TROUGH AND EMBEDDED CLOSED LOW. THE 00Z CMC  
IS FARTHER SOUTH WITH THE LATITUDE OF ITS CLOSED LOW BY THE END OF  
THE PERIOD. THE 12Z NAM HAS TRENDED TOWARD THE REASONABLY WELL  
CLUSTERED 12Z GFS/00Z UKMET AND 00Z ECMWF SOLUTIONS. THE CMC  
REMAINS SOUTH OF THE LATEST GEFS MEAN AND ECENS MEAN...AND THUS  
APPEARS TO BE AN OUTLIER SOLUTION. WILL FAVOR A NON-CMC CONSENSUS  
AT THIS TIME.  
 
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ORRISON  
 

 
 
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