842   
FXUS10 KWNH 031846  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
145 PM EST SUN NOV 03 2019  
  
VALID NOV 03/1200 UTC THRU NOV 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, DECREASING WEIGHT TO 12Z GFS/NAM  
            AFTER MONDAY AFTERNOON (05.00Z)  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
  
---18Z UPDATE---  
NO CHANGE TO THE PRELIMINARY PREFERENCE. THE 12Z ECMWF DID TREND  
LOWER WITH HEIGHTS ACROSS THE SOUTHERN TIER OF STATES ON DAY 3,  
WHICH IS IN BETTER AGREEMENT WITH THE GFS. THIS LIKELY REQUIRES  
LESS OF A DECREASE TO THE WEIGHT APPLIED TO THE 12Z NAM AND GFS  
THAN THE PRELIMINARY DISCUSSION SUGGESTS.  
  
---PREVIOUS DISCUSSION---  
MODELS CONTINUE TO EXHIBIT STRONG AGREEMENT ON THE SYNOPTIC  
PATTERN WITH MOST DETERMINISTIC MODELS WELL WITHIN THE ENVELOPE OF  
THE NAEFS+ECMWF ENSEMBLE SPREAD. ECMWF ENSEMBLE SPREAD IS NEAR OR  
BELOW THE 30-DAY AVERAGE OVER MOST OF THE CONUS, AND THESE FACTORS  
LEAD TO SOMEWHAT HIGHER FORECAST CONFIDENCE. THE MODEL PREFERENCE  
IS FOR A GENERAL MODEL BLEND.  
  
BY MONDAY NIGHT, THE 12Z NAM AND GFS BEGIN TO EXHIBIT SOME SMALL  
DEVIATIONS FROM MODEL CONSENSUS. THEY EJECT A SHORTWAVE THROUGH  
THE NORTHEAST ON TUESDAY FASTER THAN THE OTHER GLOBAL MODELS, AND  
ALSO SHOW A FLATTER FLOW PATTERN DOWNSTREAM OF A CLOSED UPPER  
LEVEL LOW OVER THE SOUTHWEST. BY WEDNESDAY, THEY ARE FORECASTING  
LOWER HEIGHTS ALOFT OVER MUCH OF THE SOUTHERN TIER OF THE COUNTRY.  
THIS DOES AFFECT SOME OF THE QPF MAGNITUDE AND DISTRIBUTION ON  
BOTH OF THE MODELS. FOR INSTANCE, ALONG COASTAL NEW ENGLAND, THE  
GFS IS CONSIDERABLY DRIER, WHILE THE REMAINING MODELS HAVE TRENDED  
TOWARD THE ECMWF WHICH HAS BEEN WETTER FOR SEVERAL MODEL CYCLES.  
  
WITH MORE CONSISTENCY FROM THE ECMWF AND ECMWF ENSEMBLE AND MODEL  
TRENDS IN THAT DIRECTION, THE PREFERENCE IS TO PLACE DECREASING  
WEIGHT ON THE GFS AND NAM BEYOND MONDAY AFTERNOON.  
  
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
LAMERS  
  
  
 
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