149   
FXUS10 KWNH 191918  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
317 PM EDT MON AUG 19 2019  
  
VALID AUG 19/1200 UTC THRU AUG 23/0000 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z MODEL EVALUATION...INCLUDING PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS/ECMWF, 06Z GEFS, 00Z ECENS  
CONFIDENCE: AVERAGE  
  
19Z UPDATE: SOME BETTER AGREEMENT WAS NOTED WITH THE REST OF THE  
12Z GUIDANCE NOW AVAILABLE, INCLUDING THE CMC WHICH NO LONGER  
APPEARS TO BE OVER AMPLIFIED OUT WEST FOR DAY 3. THERE IS OVERALL  
LESS SPREAD BETWEEN THE REST OF THE DETERMINISTIC MODELS AND THE  
EARLIER TIMING ISSUES NOTED WERE REDUCED. AS SUCH, SOME INCLUSION  
OF THE DETERMINISTIC GFS AND ECMWF CAN BE INCORPORATED FOR DAY 3,  
WHICH ARE A FAIR COMPROMISE/PROXY FOR THE REST OF THE MODEL  
GUIDANCE.  
  
---PREVIOUS DISCUSSION---  
MID TO UPPER LEVEL RIDGING WILL PERSIST THROUGH THE FORECAST  
PERIOD ACROSS THE SOUTHWEST U.S. WHILE THE NORTHERN STREAM ENERGY  
WILL BECOME INCREASINGLY AMPLIFIED FEATURING TWO TROUGHS, ONE OVER  
THE PACIFIC NW AND ANOTHER ACROSS THE GREAT LAKES REGION.  
  
IN THE FIRST 48 HOURS, MODEL AGREEMENT IS ABOVE AVERAGE WITH  
LITTLE SPREAD SEEN IN THE 500 MB HEIGHTS ACROSS THE CONUS. AS A  
RESULT, A GENERAL MODEL BLEND CAN BE APPLIED FOR THE MASS FIELDS.  
BEYOND THIS TIME FRAME, SOME NOTABLE DIFFERENCES ARE OBSERVED,  
ESPECIALLY WITH THE TROUGHS ACROSS THE NW AND GREAT LAKES REGIONS.  
TYPICAL MODEL BIASES WERE SEEN, WITH THE GFS AND NAM BEING A BIT  
FASTER WITH THE TROUGH PROGRESSION IN THE NW AND FAST AND FURTHER  
NE WITH THE TROUGH OVER THE GREAT LAKES. THE 00Z CMC WAS TOO DEEP  
OVER THE WESTERN US COMPARED TO THE REST OF THE MODEL GUIDANCE.  
  
BASED ON THIS, THE PREFERENCE IS FOR A BLEND OF THE GEFS MEAN AND  
ECENS MEAN, WHICH SEEM TO SMOOTH THE TIMING BIASES SEEN IN THE  
DETERMINISTIC RUNS AND OFFER A COMPROMISE SOLUTION AT THIS TIME.  
  
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
TAYLOR  
  
  
 
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