936  
FXUS10 KWNH 020442  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1242 AM EDT THU NOV 02 2017  
 
VALID NOV 02/0000 UTC THRU NOV 05/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
...SHORTWAVE CLIPPING THE NRN GREAT LAKES AND TRACKING ACROSS  
QUEBEC THROUGH FRIDAY WITH ASSOCIATED SURFACE LOW AND TRAILING  
COLD FRONT TO THE SOUTHWEST...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
ONLY MINOR TIMING DIFFERENCES REMAIN IN PLACE REGARDING THIS  
SYSTEM...SO A GENERAL MODEL COMPROMISE IS RECOMMENDED TO SMOOTH  
OUT THESE SMALLER SCALE DIFFERENCES.  
 
...CLOSED LOW/UPPER TROUGH TRACKING FROM THE PACIFIC NORTHWEST  
TODAY INTO THE NRN PLAINS FOR THIS WEEKEND...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z CMC/00Z NAM/12Z ECMWF BLEND  
CONFIDENCE: AVERAGE  
 
SOME MINOR TIMING/STRENGTH DIFFERENCES EXIST EARLY ON WITH THIS  
SYSTEM BUT THESE DIFFERENCES GROW THROUGH THE WEEKEND. THE 12Z  
UKMET STANDS OUT AS A FASTER OUTLIER OF THE LATEST DETERMINISTIC  
MODELS AND IT LIES TOWARD THE FASTER EDGE OF THE LATEST ENSEMBLE  
GUIDANCE. THE 00Z GFS AND 12Z ECMWF HAVE BEEN CONSISTENT FROM RUN  
TO RUN WITH THE GFS A BIT WEAKER ALOFT AND THE ECMWF  
STRONGER/SLOWER. THE MIDDLE GROUND OF THE ENSEMBLES SUPPORT A  
BLEND CLOSEST TO THE 00Z NAM...12Z CMC AND 12Z ECMWF...WITH THE  
ECMWF SLOWER THAN THE NAM/CMC.  
 
...MID-UPPER LEVEL SHORTWAVE AMPLIFYING TOWARD THE PACIFIC  
NORTHWEST SAT INTO SUN...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
RELATIVELY GOOD ENSEMBLE AGREEMENT IS IN PLACE WITH THIS SYSTEM  
THROUGH SUN MORNING...AND THE LATEST DETERMINISTIC MODELS ALSO  
SHOW GOOD AGREEMENT AS WELL SO A GENERAL MODEL BLEND IS PREFERRED  
WITH THIS SYSTEM.  
 
...UPPER LEVEL SHORTWAVE OVER THE SOUTHWEST EARLY THU  
MORNING...TRACKING EASTWARD THROUGH FRI AND AMPLIFYING OVER  
FLORIDA ON SAT...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON 12Z UKMET BLEND  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
 
SIGNIFICANT ENSEMBLE SPREAD EXISTS WITH THIS SYSTEM AS IT REACHES  
THE SOUTHEASTERN U.S. BUT THE LATEST DETERMINISTIC GUIDANCE IS IN  
DECENT AGREEMENT WITH THE ENSEMBLE MEANS EXCEPT FOR THE 12Z UKMET  
WHICH IS DISPLACED TO THE SOUTH. A NON 12Z UKMET BLEND IS  
PREFERRED AT THIS TIME.  
 
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
OTTO  
 

 
 
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