455  
FXUS10 KWNH 040433  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1233 AM EDT SAT NOV 04 2017  
 
VALID NOV 04/0000 UTC THRU NOV 07/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z NAM/GFS PREFERENCES WITH PRELIMINARY PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT  
RANGE FORECASTS.  
 
...SHORTWAVE MOVING FROM MT TODAY INTO QUEBEC BY MONDAY MORNING  
WITH TRAILING COLD FRONT ACROSS THE GREAT LAKES INTO THE SRN  
PLAINS...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL COMPROMISE  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS HAVE CONTINUED TO SHOW CONVERGENCE WITH SUBSEQUENT  
MODEL CYCLES REGARDING TIMING OF THE SHORTWAVE TRACKING EAST. THE  
12Z ECMWF/CMC ARE SLIGHTLY SLOWER WITH THIS SHORTWAVE AND THE 12Z  
UKMET REMAINS SLIGHTLY FASTER THAN THE 00Z GFS AND 00Z NAM.  
DIFFERENCES WITH THE TIMING OF THE TRAILING COLD FRONT ARE ALSO  
MINIMAL SUCH THAT A GENERAL MODEL BLEND CAN BE USED FOR THIS  
SYSTEM.  
 
...POSITIVELY TILTED SHORTWAVE CROSSING THROUGH THE PACIFIC  
NORTHWEST ON SUN...REACHING THE NRN INTERMOUNTAIN REGION FOR  
MONDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON 00Z NAM BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
DIFFERENCES WITH THIS SYSTEM BEGIN TO APPEAR BY MONDAY WITH THE  
00Z NAM HOLDING MORE MID-LEVEL ENERGY BACK ACROSS THE NRN GREAT  
BASIN WITHIN THE TAIL END OF THE SHORTWAVE TROUGH. TRENDS IN THE  
ENSEMBLE SPAGHETTI HEIGHTS FOR 500 MB HAVE SHOWN LESS MEMBERS  
HANGING A PORTION OF THE TROUGH BACK AS SEEN IN THE 00Z NAM.  
ENSEMBLE MEANS SUPPORT SOMETHING BETWEEN THE 12Z ECMWF WHICH IS A  
LITTLE WEST OF THE 00Z GFS AND 12Z UKMET. THE 12Z CMC IS NEAR THE  
MIDDLE. A NON 00Z NAM BLEND SHOWS REASONABLY CLOSE FOR THIS SYSTEM  
AND SUPPORTS THE LATEST TRENDS IN THE ENSEMBLE GUIDANCE.  
 
   
..UPPER TROUGH MOVING BY FLORIDA SAT/SUN
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL COMPROMISE  
CONFIDENCE: ABOVE 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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