706  
FXUS10 KWNH 101631  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1130 AM EST FRI NOV 10 2017  
 
VALID NOV 10/1200 UTC THRU NOV 14/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH LATEST MODEL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
   
..LEAD SHORTWAVE OVER NORTHWEST MT
 
EJECTING EAST ALONG THE  
US-CANADA BORDER THROUGH THE WEEKEND...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF 12Z NAM...12Z GFS AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THIS SHORTWAVE IS AN INITIAL WAVE GETTING KICKED OUT OF THE  
BROADER TROUGH NEAR THE PACIFIC NORTHWEST COAST CURRENTLY. THE 00Z  
CMC BECOMES A SLOW OUTLIER WITH THIS ENERGY BY EARLY SATURDAY AS  
IT TRAVERSES THE U.S./CANADIAN BORDER. THE CMC ACTUALLY SLOWS THE  
SYSTEM TO THE POINT WHERE IT ATTEMPTS TO PHASE WITH A TRAILING  
SHORTWAVE WHICH IS THE AFOREMENTIONED TROUGH NEAR THE PACIFIC  
NORTHWEST. THE REMAINING MODELS ARE IN GOOD AGREEMENT IN GRADUALLY  
DAMPENING THIS INITIAL SYSTEM OUT AS IT CLIPS THE UPPER GREAT  
LAKES REGION AND NORTHERN MAINE THROUGH SUNDAY. THE 00Z UKMET BY  
LATE IN THE WEEKEND ALSO MAY BE A TAD SLOW...WITH THE BETTER MODEL  
CLUSTERING FAVORING THE 12Z NAM/12Z GFS AND 00Z ECMWF. A BLEND OF  
THESE SOLUTIONS WILL BE PREFERRED GIVEN GOOD ENSEMBLE SUPPORT.  
 
...CLOSED LOW JUST OFFSHORE OF THE PACIFIC NORTHWEST OPENING INTO  
A TROUGH AND MOVING ONSHORE TODAY...   
..BROAD TROUGH REACHING THE NORTHERN PLAINS SATURDAY
 
AND THE  
GREAT LAKES BY SUNDAY...  
...ENERGY REACHING THE MID-ATLANTIC AND NORTHEAST WITH WAVE  
DEVELOPMENT OFFSHORE BY MONDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF 12Z GFS...12Z UKMET AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE MODELS SHOW GOOD AGREEMENT WITH THIS SYSTEM AS IT TRAVERSES  
THE WESTERN U.S. AND EJECTS OUT ACROSS THE NORTHERN PLAINS THROUGH  
SATURDAY. HOWEVER...BY SUNDAY AS THE SYSTEM MOVES THROUGH THE  
GREAT LAKES AND OH VALLEY...THE 12Z NAM AND ESPECIALLY THE 12Z CMC  
BEGIN TO BECOME MORE AMPLIFIED THAN ANY OTHER SOLUTION...AND THE  
CMC ALSO BEGINS TO BECOME A BIT MORE PROGRESSIVE. THIS CARRIES  
OVER THROUGH MONDAY AS THE ENERGY REACHES THE MID-ATLANTIC AND  
NORTHEAST. THE STRONGER NAM AND CMC LEAD TO A STRONGER SURFACE  
RESPONSE OFFSHORE SOUTHERN NEW ENGLAND AS CYCLOGENESIS TAKES  
PLACE. THE 12Z GFS/00Z UKMET AND 00Z ECMWF ARE ALL A BIT WEAKER  
WITH THIS SYSTEM AND ALSO HAVE RATHER STRONG ENSEMBLE SUPPORT WITH  
A FLATTER WAVE. WILL PREFER A BLEND OF THE WEAKER CONSENSUS AT  
THIS TIME...AND GIVEN THE PROGRESSIVE NATURE OF THE MEAN LAYER  
FLOW...THE SURFACE WAVE SHOULD MOVE OUT TO SEA WITH ONLY MODEST  
IMPACTS TO NEW ENGLAND.  
 
...UPPER TROUGH DROPPING SOUTH OFFSHORE THE PACIFIC NORTHWEST THIS  
WEEKEND BEFORE MOVING INLAND ON MONDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC CONSENSUS  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE GUIDANCE CONTINUES TO ALLOW A DEEP UPPER TROUGH AND ASSOCIATED  
CLOSED LOW TO DROP SOUTH THROUGH THE WEEKEND OFFSHORE THE PACIFIC  
NORTHWEST BEFORE THEN PIVOTING EAST AND INLAND ACROSS THE  
NORTHWEST THROUGH MONDAY. THIS WILL DRIVE LOW PRESSURE ACROSS  
VANCOUVER ISLAND AND A COLD FRONT INLAND ACROSS THE COASTAL RANGES  
OF WA/OR AND INTERIOR SECTIONS OF THE NORTHWEST. THE 00Z CMC IS A  
BIT SLOWER WITH THE HEIGHT FALL EVOLUTION SURFACE LOW PROGRESSION  
COMPARED TO THE REMAINING MODELS WHICH ARE REASONABLY WELL  
CLUSTERED WITH TIMING AND DEPTH OUTSIDE OF SOME MINOR DETAIL  
DIFFERENCES. WILL SUGGEST A NON-CMC CONSENSUS AT THIS TIME.  
 
...POWERFUL OCCLUDING CYCLONE OVER EASTERN CANADA TODAY AND  
SATURDAY WITH ACCOMPANYING COLD FRONT SURGING THROUGH THE  
NORTHEASTERN US...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
MODELS SHOW VERY GOOD AGREEMENT WITH THIS SYSTEM WITH ALL OF THE  
MASS FIELDS...AND THUS WILL CONTINUE TO PREFER A GENERAL MODEL  
BLEND.  
 
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WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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