754  
FXUS10 KWNH 081632  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1132 AM EST WED NOV 08 2017  
 
VALID NOV 08/1200 UTC THRU NOV 12/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH FINAL PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..POSITIVELY TILTED TROUGH CROSSING THE PLAINS TODAY
 
   
..ENERGY REACHING THE SOUTHEAST BY THURSDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE MODELS TAKE A POSITIVELY-TILTED TROUGH EAST OUT ACROSS THE  
PLAINS TODAY WITH THE ENERGY REACHING THE SOUTHEAST BY THURSDAY  
BEFORE THEN EXITING OFF THE SOUTHEAST COAST THURSDAY NIGHT. MOST  
OF THE MODELS SHOW SOME OF THE ENERGY BECOMING A LITTLE MORE  
CONCENTRATED/AMPLIFIED OVER THE SOUTHEAST LATE THURSDAY BEFORE THE  
SYSTEM GOES OFFSHORE...BUT ALL OF THE MODELS MAINTAIN A  
PROGRESSIVE TROUGH AXIS. THE WEAKEST SOLUTION IS THE 00Z CMC AND  
FOLLOWED TO AN EXTENT BY THE 12Z NAM. THE 12Z GFS/00Z UKMET AND  
00Z ECMWF ARE ALL A LITTLE SLOWER AND DEEPER THAN THE CMC AND NAM  
SOLUTIONS. BETTER ENSEMBLE SUPPORT RESIDES WITH THE STRONGER  
CAMP...AND SO A BLEND OF THE GFS/UKMET AND ECMWF WILL BE PREFERRED.  
 
...DEEP CYCLONE DROPPING FROM THE GULF OF ALASKA TO OFFSHORE OF  
THE PACIFIC NORTHWEST...   
..OPENING INTO A TROUGH OVER THE NORTHWEST BY FRIDAY
 
   
..ENERGY EJECTING DOWNSTREAM TOWARD THE MIDWEST BY SATURDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
A DEEP UPPER LOW OVER THE GULF OF AK WILL DROP SOUTH-SOUTHEAST AND  
THEN GRADUALLY EAST TOWARD THE PACIFIC NORTHWEST BY THURSDAY  
BEFORE THEN WEAKENING INTO A PROGRESSIVE TROUGH AXIS AND MOVING  
INLAND ACROSS THE NORTHWEST ON FRIDAY. THEREAFTER...A PORTION OF  
THE ENERGY WILL BREAK AWAY AND STREAM DOWNWIND ACROSS THE NORTHERN  
PLAINS AND TOWARD THE UPPER MIDWEST. A SLOWER PIECE OF THE TROUGH  
THOUGH WILL LINGER BACK OVER THE NORTHERN INTERMOUNTAIN REGION AND  
IMMEDIATE HIGH PLAINS THROUGH SATURDAY. THE 12Z NAM GENERALLY  
APPEARS A LITTLE SLOWER AND STRONGER THAN THE MODELS CONSENSUS  
WITH ITS HEIGHT FALLS TRAVERSING THE NORTHERN TIER STATES THROUGH  
SATURDAY. THE 00Z CMC IS OVERALL IS THE SLOWEST SOLUTION HERE WITH  
THE 00Z UKMET TENDING TO SUPPORT THE WELL CLUSTERED 12Z GFS AND  
00Z ECMWF. FARTHER BACK OVER THE INTERMOUNTAIN WEST...THE CMC IS  
THE SLOWEST WITH THIS PORTION OF THE ENERGY...WITH NAM LIKELY A  
TAD TOO DEEP AND THE UKMET TOO WEAK. OVERALL...THE GFS AND ECMWF  
APPEAR TO COLLECTIVELY HAVE THE BETTER HANDLE ON THIS SYSTEM AS IT  
INITIALLY COMES INTO THE NORTHWEST AND EVOLVES DOWNSTREAM...AND SO  
A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED AT THIS TIME.  
 
   
..AMPLIFYING NORTHERN STREAM TROUGH/CLOSED LOW NEAR GREAT LAKES
 
   
..COLD FRONT CROSSING THE NORTHERN TIER STATES THROUGH FRIDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET CONSENSUS  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS ARE IN GOOD AGREEMENT WITH THE THE DETAILS OF A  
VIGOROUS NORTHERN STREAM TROUGH THAT AMPLIFIES INTO A CLOSED LOW  
NORTH OF THE GREAT LAKES REGION ACROSS ONTARIO AND SOUTHERN QUEBEC  
BY THE END OF THE WEEK. HOWEVER...THE 00Z UKMET TAKES ITS SURFACE  
LOW EXITING OUT OF THE GREAT LAKES REGION OCCASIONALLY A BIT TO  
THE LEFT OF THE MODEL CONSENSUS. OVERALL...THE PLACEMENT  
DIFFERENCES ARE RATHER MINOR...BUT A NON-UKMET CONSENSUS WILL BE  
PREFERRED FOR NOW.  
 
   
..UPPER TROUGH OFFSHORE THE PACIFIC NORTHWEST ON SATURDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS/00Z CMC AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE GUIDANCE SHOWS A RELATIVELY DEEP UPPER TROUGH AND ASSOCIATED  
CLOSED LOW DROPPING DOWN FROM THE GULF OF AK AND DOWN TOWARD THE  
PACIFIC NORTHWEST THROUGH SATURDAY. THE 12Z NAM AND 00Z UKMET TEND  
TO DROP MORE ENERGY FARTHER DOWN TO THE SOUTH COMPARED TO THE 12Z  
GFS/00Z CMC AND 00Z ECMWF BY THE END OF THE PERIOD.  
OVERALL...THERE IS A BIT BETTER ENSEMBLE SUPPORT TOWARD THE  
GFS/CMC AND ECMWF...SO A BLEND OF THESE SOLUTIONS WILL BE  
PREFERRED.  
 
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ORRISON  
 

 
 
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