769  
FXUS10 KWNH 050443  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1242 AM EDT SUN NOV 05 2017  
 
VALID NOV 05/0000 UTC THRU NOV 08/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT  
RANGE FORECASTS.  
 
...SHORTWAVE TRACKING THROUGH ONTARIO TODAY AND QUEBEC ON MONDAY  
WITH TRAILING COLD FRONT EXTENDING FROM THE GREAT LAKES/NORTHEAST  
TO THE SOUTHERN PLAINS...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
ONLY MINOR TIMING DIFFERENCES EXIST WITH THE MID-LEVEL SHORTWAVE  
AND SURFACE COLD FRONT THROUGH MONDAY. THE 00Z GFS IS SLIGHTLY  
FASTER THAN THE REMAINING DETERMINISTIC GUIDANCE WHILE THE 12Z  
ECMWF IS A LITTLE SLOWER CONCERNING THE COLD FRONT MOVING THROUGH  
THE OHIO VALLEY. GIVEN THE LATEST DIFFERENCES ARE RATHER SMALL...A  
GENERAL MODEL BLEND IS RECOMMENDED FOR THIS SYSTEM.  
 
...POSITIVELY TILTED TROUGH TRANSLATING FROM THE PACIFIC NORTHWEST  
TODAY TO THE CENTRAL ROCKIES BY TUESDAY EVENING...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z GFS/12Z ECMWF/12Z UKMET BLEND  
CONFIDENCE: AVERAGE  
 
THE 00Z NAM IS NOTICEABLY STRONGER AND SLOWER WITH THE NORTHERN  
REFLECTION OF THIS SHORTWAVE...WHICH IS EXPECTED TO MOVE THROUGH  
THE UPPER MIDWEST ON TUESDAY. GOOD AGREEMENT HERE FOR A NON-00Z  
NAM BLEND. REGARDING THE PORTION OF THE TROUGH OVER THE  
ROCKIES...THE LATEST ENSEMBLE SPAGHETTI PLOTS SHOW A FAIR DEGREE  
OF SPREAD WITH THE 12Z ECMWF MEAN LESS AMPLIFIED THAN THE 12Z  
ECMWF. REGARDING THE WEAKER GFS/GEFS...THE 12Z GEFS MEAN IS  
STRONGER THAN THE 12Z GFS BUT SLIGHTLY WEAKER THAN THE 00Z GFS.  
THE END RESULT IS FOR A SOLUTION IN THE MIDDLE...BETWEEN THE  
STRONGER AND WEAKER MODELS...WHICH IS A BLEND OF THE 00Z GFS/12Z  
ECMWF/12Z UKMET.  
 
...DEEP CYCLONE LOCATED OFFSHORE OF THE PACIFIC NORTHWEST BY  
WEDNESDAY MORNING...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z GFS...00Z NAM...12Z UKMET BLEND  
CONFIDENCE: AVERAGE  
 
OVERALL ENSEMBLE TRENDS HAVE BEEN FASTER TO BRING THE LARGE CLOSED  
LOW CLOSER TO SHORE OVER THE PAST 4 12Z/00Z CYCLES. WHILE MODEL  
DIFFERENCES ARE NOT TOO LARGE..THE PREFERENCE IS TO STAY TOWARD  
THE FRONT EDGE OF THE LATEST DETERMINISTIC DIFFERENCES GIVEN  
ENSEMBLE TRENDS. THIS IS CLOSEST TO A 00Z NAM...00Z GFS AND 12Z  
UKMET BLEND. THE 12Z ECMWF WAS A BIT FARTHER OFFSHORE THAN DESIRED  
BY WED MORNING.  
 
   
..UPPER TROUGH DEPARTING FROM FLORIDA TODAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL COMPROMISE  
CONFIDENCE: AVERAGE  
 
THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.  
 
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
OTTO  
 

 
 
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