071  
FXUS10 KWNH 150456  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1155 PM EST THU NOV 14 2019  
 
VALID NOV 15/0000 UTC THRU NOV 18/1200 UTC  
 
..SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z NAM, GFS; 12Z ECMWF  
NAM EXCLUDED ON DAY 3 (AFTER 17.12Z)  
CONFIDENCE: AVERAGE  
 
THE MOST SUBSTANTIAL MODEL DIFFERENCES ARE RELATED TO A STRONG  
UPPER LEVEL LOW APPROACHING THE SOUTHEAST ATLANTIC COAST AND  
RELATED CYCLOGENESIS OFF THE COAST OF THE CAROLINAS. OVER THE  
REMAINDER OF THE CONUS, MODEL FORECAST PRECIPITATION IS EITHER  
VERY LIMITED OR IN FAIRLY GOOD AGREEMENT IN AREAS OF STRONGER  
OROGRAPHIC ASCENT IN THE PACIFIC NORTHWEST.  
 
FOR THE SOUTHEAST, THE 00Z NAM CONTINUES TO PRODUCE A SURFACE LOW  
CLOSER TO THE COAST, YIELDING HIGHER QPF OVER LAND AREAS. THE ONLY  
RELATIVELY COMPARABLE DETERMINISTIC MODEL FORECAST IS FROM THE 12Z  
CMC, WHICH HAS ITS SURFACE LOW POSITIONED SLIGHTLY FURTHER  
OFFSHORE. THE REMAINING MODELS ARE SLOWER AND FURTHER OFFSHORE,  
AND HAVE LESS QPF OVER LAND AREAS. THE TREND ON THE PAST SEVERAL  
RUNS OF THE GFS HAS BEEN SLOWER AND THERE IS BETTER ENSEMBLE  
SUPPORT FOR A LOW POSITION FURTHER OFFSHORE. NEVERTHELESS, GIVEN  
THE STRENGTH OF THE UPPER LEVEL LOW APPROACHING THE COAST AND THE  
PROXIMITY OF THE SEA-SURFACE TEMPERATURE GRADIENT TO THE COAST, A  
SCENARIO CLOSER TO THE NAM IS NOT UNREASONABLE. THE MODEL  
PREFERENCE IS FOR A BLEND OF THE NAM, GFS AND ECMWF TO PLACE  
GREATER WEIGHT ON AN OFFSHORE SCENARIO, BUT INCORPORATE SOME  
POTENTIAL FOR A CLOSER APPROACH TO THE COAST.  
 
BY SUNDAY, THE NAM BEGINS TO DIVERGE MORE SIGNIFICANTLY FROM OTHER  
MODELS, DRAWING THE SURFACE LOW NORTH TOWARD NEW ENGLAND, WHILE  
THE REMAINING MODELS HAVE A TRACK MUCH FURTHER SOUTHEAST. THIS IS  
RELATED TO DIFFERENCES WITH AN UPSTREAM SHORTWAVE DIGGING THROUGH  
THE MIDWEST, AND THE INITIAL POSITION OF THE SURFACE LOW BEING  
FURTHER NORTHWEST THAN THE REMAINING MODELS. THE ENSEMBLE SUPPORT  
FOR SUCH A SCENARIO IS EVEN MORE LIMITED, AND AS A RESULT THE NAM  
IS EXCLUDED FROM THE MODEL PREFERENCE AFTER 12Z SUNDAY.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
LAMERS  
 

 
 
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