550   
FXUS10 KWNH 141705  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
104 PM EDT WED AUG 14 2019  
  
VALID AUG 14/1200 UTC THRU AUG 18/0000 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND OUTSIDE OF THE NORTH-CENTRAL U.S.  
            12Z NAM/00Z ECMWF BLEND IN NORTH-CENTRAL U.S.  
CONFIDENCE: AVERAGE  
  
THE UPPER LEVEL PATTERN STARTS OFF WITH STRONG RIDGING ACROSS THE  
SOUTHWEST AND NORTHWESTERLY FLOW TO ITS NORTH, LEADING TO BROAD  
TROUGHING ACROSS THE EASTERN HALF OF THE NATION. THE RIDGE BECOMES  
SUPPRESSED ON FRIDAY AS UPPER LEVEL TROUGHING BEGINS TO IMPINGE  
UPON THE NORTHWEST, LEADING TO BROAD QUASI-ZONAL FLOW FROM THE  
PACIFIC NORTHWEST TO THE NORTHEAST.  
  
ANOMALOUS MOISTURE WILL REMAIN IN PLACE AHEAD OF A SLOW MOVING  
FRONT WHICH WILL EXTEND FROM THE MID-ATLANTIC REGION TO THE GULF  
COAST, WHILE IMPULSES IN NORTHWEST FLOW ALOFT KEEP THE CENTRAL  
PLAINS TO THE MIDWEST ACTIVE WITH ORGANIZED CONVECTION. THERE IS  
BROAD AGREEMENT WITH THE SYNOPTIC SCALE FEATURES ACROSS THESE TWO  
AREAS WITH A GENERAL MODEL BLEND RECOMMENDED. ELSEWHERE, A GENERAL  
MODEL BLEND ACROSS THE CONUS APPEARS OKAY AS WELL.  
  
THE ONE AREA WHERE THE MODELS SHOW DIFFERENCES IS WITH A COLD  
FRONT, RELATED TO UPPER LEVEL TROUGHING IN SASKATCHEWAN AND  
ALBERTA FRIDAY NIGHT INTO SATURDAY. HERE, THE 12Z GFS SHOWS AS A  
NEAR OUTLIER WITH A MORE PROGRESSIVE TROUGH RELATED TO VORTICITY  
WRAPPING AROUND THE WEST SIDE OF A CLOSED LOW IN NORTHERN  
SASKATCHEWAN. THE 00Z ECMWF IS ON THE OTHER EXTREME, BUT WITHIN  
THE SPREAD, REGARDING THE VORTICITY MAX DROPPING SOUTH TO THE WEST  
OF THE CLOSED LOW IN NORTHERN SASKATCHEWAN. A 12Z NAM/00Z ECMWF  
BLEND REPRESENTS CLOSEST TO THE ENSEMBLE MEANS.   
  
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
OTTO  
  
  
 
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