962  
FXUS10 KWNH 181621  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1220 PM EDT WED SEP 18 2019  
 
VALID SEP 18/1200 UTC THRU SEP 22/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND INCREASINGLY WEIGHTED TOWARD  
ECMWF ENSEMBLE AND GEFS ENSEMBLE MEANS BY DAY 3  
CONFIDENCE: AVERAGE  
 
THE SYNOPTIC PATTERN WILL CONTINUE TO BE DOMINATED BY A WESTERN  
U.S. TROUGH AND AN EASTERN U.S. RIDGE. IN GENERAL, THE MODELS ARE  
IN GOOD AGREEMENT OVER THE FIRST COUPLE DAYS OF THE FORECAST, WITH  
INCREASING DIFFERENCES BY DAY 3 (FRIDAY NIGHT AND SATURDAY)  
RELATED TO HOW THE TROUGH EJECTS EAST INTO THE PLAINS. THE 00Z  
ECMWF AND CMC SHOWED THE TROUGH LAGGING BACK IN THE WEST, WHILE  
THE 12Z GFS, NAM AND 00Z UKMET WERE FASTER AND LESS AMPLIFIED WITH  
THE TROUGH. BOTH SCENARIOS HAVE A REASONABLE AMOUNT OF ENSEMBLE  
SUPPORT, AND THE ENSEMBLE MEANS ARE POSITIONED AROUND A MEDIAN  
TIMING. THEREFORE, THE MODEL PREFERENCE WILL BE TRENDED TOWARD THE  
ENSEMBLE MEANS BY DAY 3. THIS MAY HAVE AN EFFECT ON THE TRACK OF  
THE REMNANT CIRCULATION OF IMELDA OVER THE SOUTH-CENTRAL U.S., AND  
AN APPROACH THAT FOLLOWS THE ENSEMBLE MEANS IS ALSO PREFERRED FOR  
THAT SYSTEM.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
LAMERS  
 
 
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