061   
FXUS10 KWNH 081926  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
326 PM EDT THU AUG 08 2019  
  
VALID AUG 08/1200 UTC THRU AUG 12/0000 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z FINAL MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND  
CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND, WITH SLIGHTLY LESSER WEIGHT ON  
THE 12Z GFS/UKMET/CMC  
CONFIDENCE: AVERAGE  
   
..19Z UPDATE  
  
NO MAJOR CHANGES TO THE PREVIOUS THINKING IN TERMS OF MODEL  
PREFERENCES AS THE 12Z CMC AND ECMWF ARE SIMILAR TO THEIR PREVIOUS  
RUNS.  IT STILL SEEMS THAT THE MOST NOTABLE DIFFERENCE ARE ACROSS  
THE PACIFIC NORTHWEST WITH THE APPROACHING TROUGH/ENERGY AND THE  
TROUGH AXIS MOVING OFF THE EAST COAST.  SEEMS TIMING AND INTENSITY  
ARE IN QUESTION, THOUGH THE DIFFERENCES REMAIN SUBTLE WITH NO REAL  
IMPACTS TO SURFACE FEATURES OVERALL.  
   
..PREVIOUS DISCUSSION  
  
MODELS ARE IN FAIRLY GOOD AGREEMENT IN TERMS OF THE MASS FIELDS. A  
TROUGH WILL APPROACH THE WEST COAST WHILE RIDGING ACROSS THE  
PLAINS SLIDES SLOWLY EAST AND FLATTENS AS MID-LEVEL IMPULSES HELP  
TO LOWER HEIGHTS ACROSS THE NORTHERN ROCKIES.  THE TROUGH IN THE  
EAST WILL DEAMPLIFY AS THE RIDGE APPROACHES AND THE ENERGY SHIFTS  
FARTHER NORTH. A BROAD-BASED MODEL BLEND IS PREFERRED FOR MASS  
FIELDS ACROSS NORTH AMERICA, WITH MORE FOCUS ON HIGHER RESOLUTION  
GUIDANCE FOR QPF.  
  
DIFFERENCES WERE NOTED ACROSS THE PACIFIC NORTHWEST ASSOCIATED  
WITH THE TROUGH AND ENERGY MOVING OVER THE NORTHERN TIER OF THE  
RIDGE AXIS SATURDAY INTO SUNDAY.  THE 12Z GFS WAS SLIGHTLY OUT OF  
TOLERANCE COMPARED TO THE MODEL SUITE/ENSEMBLES IN TERMS OF TIMING  
AND INTENSITY OF THE UPPER LOW AND MID-LEVEL ENERGY. THOUGH IT IS  
WITHIN THE MODEL CLUSTERING.  ALSO, THE 12Z UKMET/00Z CMC APPEARS  
TO BE MORE AMPLIFIED WITH THE MID-LEVEL TROUGH AXIS OFF THE EAST  
COAST DURING THE WEEKEND WITH A SLIGHTLY FLATTER FLOW PATTERN  
ACROSS THE GREAT LAKES REGION.  THESE DIFFERENCE DO NOT APPEAR TO  
DRAMATICALLY IMPACT THE RESULTANT PRECIPITATION.   
  
GIVEN THIS, PREFERENCE WAS TOWARD A GENERAL MODEL BLEND CONUS  
WIDE, WITH LESSER WEIGHT ON THE 12Z GFS IN THE PACIFIC NORTHWEST  
AND LESSER WEIGHT TOWARD THE 12Z UKMET/CMC IN THE NORTHEAST.   
  
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
PAGANO  
  
  
 
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