787  
FXUS10 KWNH 130632  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
231 AM EDT FRI OCT 13 2017  
 
VALID OCT 13/0000 UTC THRU OCT 16/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL PREFERENCES WITH CONFIDENCE INTERVALS  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT  
RANGE FORECASTS.  
 
KICKER SHORTWAVE DROPPING INTO THE GREAT LAKES SUNDAY NIGHT  
FRONT MOVING INTO THE GREAT LAKES/NORTHEAST FRIDAY/SATURDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
SINCE THERE REASONABLE MODEL AGREEMENT WITH THESE SYSTEMS, PREFER  
A COMPROMISE OF THE 00Z UKMET, 00Z ECMWF, 00Z CANADIAN, 00Z NAM,  
AND 00Z GFS WITH ABOVE AVERAGE CONFIDENCE.  
 
SYSTEM MOVING FROM THE NORTHWEST INTO THE GREAT LAKES SUNDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GFS/UKMET/ECMWF BLEND; CONFIDENCE SLIGHTLY ABOVE AVE  
 
BY SUNDAY MORNING, THE 00Z NAM BECOMES SLOW AND DEEP WITH THIS  
SYSTEM WHILE THE 00Z CANADIAN SHOWS A MORE DEPRESSED/SOUTHWARD  
SURFACE TRACK. THE GUIDANCE HAS BEEN TRENDING NORTHEAST, THE  
GENERAL FLOW PATTERN IS DEAMPLIFYING AT THAT POINT IN TIME, AND  
THE NAM'S SOLUTION FITS ITS USUAL BIAS AT THIS TIME RANGE, SO PLAN  
ON DISCOUNTING ITS SOLUTION. THE 00Z CANADIAN LIES ON THE  
SOUTHERN EXTREMITY OF THE 12Z GLOBAL ENSEMBLE LOW CLUSTERING, AND  
CAN BE TOO FAR SOUTH WITH LOW TRACKS, SO DID NOT CONSIDER IT  
VIABLE. PREFER A COMPROMISE OF THE 00Z GFS, 00Z UKMET, AND 00Z  
ECMWF WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.  
 
TROPICAL WAVE MOVING THROUGH THE FL STRAITS  
LINGERING UPPER TROUGH/UPPER LOW NEAR THE BAHAMAS INTO MONDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND; CONFIDENCE SLIGHTLY ABOVE AVE  
 
THE 00Z UKMET IS UNIQUELY WEAK WITH THIS SYSTEM OVER THE NEXT 84  
HOURS, THOUGH IT HAS SHOWN SOME STRENGTHENING TREND BY SUNDAY  
NIGHT WHEN COMPARED TO ITS PRIOR RUN. WITH THE 00Z GEFS AND 12Z  
ECMWF ENSEMBLE MEAN SOLUTIONS SUPPORTING THE STRONGER CONSENSUS,  
PREFER A COMPROMISE OF THE 00Z NAM, 00Z GFS, 00Z CANADIAN, AND 00Z  
ECMWF WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.  
 
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ROTH  

 
 
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