870  
FXUS10 KWNH 031638  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1237 PM EDT SAT AUG 03 2019  
 
VALID AUG 03/1200 UTC THRU AUG 07/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
MODELS ARE IN FAIRLY GOOD AGREEMENT ACROSS THE CONUS OVER THE NEXT  
FEW DAYS. THE SYNOPTIC PATTERN REMAINS RELATIVELY CONSISTENT, WITH  
A PERSISTENT RIDGE IN THE WESTERN U.S. AND A TROUGH OVER THE EAST  
THAT GETS REINFORCED BY SOME DIGGING SHORTWAVE EMBEDDED WITHIN  
DEEPER LAYER NORTHWEST FLOW ALOFT.  
 
THE PRIMARY DIFFERENCES ARE RELATED TO THE TROUGH AMPLITUDE IN THE  
SOUTHEAST AND GULF OF MEXICO ON MONDAY AND TUESDAY. THE 12Z  
NAM/GFS AND 06Z GEFS MEAN JUST LIKE THE PREVIOUS CYCLES TEND TO  
SHOW AT LEAST A MODESTLY MORE AMPLIFIED TROUGH, WHILE THE 00Z  
NON-NCEP GUIDANCE LED BY THE UKMET, CMC AND ECMWF ARE A TAD  
WEAKER. THE EUROPEAN AND CANADIAN ENSEMBLE MEMBERS TEND TO FAVOR  
THE SLIGHTLY LESS AMPLIFIED TROUGH, BUT GIVEN THE STRENGTH OF THE  
DEEP LAYER RIDGE OVER THE FOUR CORNERS REGION OF THE COUNTRY, A  
RELATIVELY STRONG TELECONNECTING DOWNSTREAM TROUGH PER THE NAM AND  
GFS IS CERTAINLY FEASIBLE AND CANNOT BE RULED OUT.  
 
ONE OTHER DIFFERENCE OF NOTE IS THAT THE 00Z UKMET IS A TAD SLOWER  
WITH THE COLD FRONT EVOLUTION ACROSS THE UPPER MIDWEST BY LATE  
MONDAY AND TUESDAY, AND HAS A SOMEWHAT STRONGER SURFACE LOW RIDING  
ALONG IT COMPARED TO THE OTHER MODELS.  
 
BASED ON THE LATEST MODEL CLUSTERING AND ENSEMBLE DATA SETS, A  
GENERAL MODEL BLEND SHOULD STILL SUFFICE ACROSS THE CONUS FOR THE  
MODEL MASS FIELD PREFERENCES.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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