435   
FXUS10 KWNH 181637  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1136 AM EST TUE FEB 18 2020  
  
VALID FEB 18/1200 UTC THRU FEB 22/0000 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
OVERALL PATTERN ACROSS THE CONUS  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 48 HOURS; 06Z GEFS, 00Z  
ECMWF/ECENS BLEND THEREAFTER  
CONFIDENCE: AVERAGE TO SLIGHTLY ABOVE AVERAGE, EXCEPT BELOW  
AVERAGE FOR NC/VA COASTAL SYSTEM DAY 3  
  
POSITIVELY TILTED TROUGH AXIS CURRENTLY ACROSS PORTIONS OF THE  
CENTRAL/EASTERN US IS EXPECTED TO SLOWLY ADVANCE EASTWARD THROUGH  
THE NEXT COUPLE OF DAYS AS A NORTHERN STREAM SHORTWAVE DROPS FROM  
THE CANADIAN ROCKIES INTO THE GREAT LAKES REGION BY DAY 2.  
UPSTREAM RIDGING WILL BUILD ACROSS THE WESTERN US AND INTERIOR  
ROCKIES FOR DAY 2 INTO PORTIONS OF DAY 3 BEFORE A CLOSED LOW  
SLIDES DOWN OFFSHORE THE WEST COAST. THE SURFACE PATTERN WILL BE  
REFLECTED BY A LARGE DOME OF ARCTIC HIGH PRESSURE OVER THE  
CENTRAL/EASTERN US. TOWARD THE END OF DAY 3, A LOW PRESSURE MAY  
FORM OFF THE NC COAST.  
  
THROUGH 48 HOURS, A GENERAL MODEL BLEND IS PREFERRED AS FOR THE  
LARGE SCALE MASS FIELDS THERE IS RELATIVELY LITTLE SPREAD SEEN  
FROM A DETERMINISTIC PERSPECTIVE AND THE ENSEMBLE SPREAD IS FAIRLY  
LOW. FOR DAY 3, THE MOST NOTABLE MODEL SPREAD LIES ACROSS THE  
SOUTHEASTERN US AND WHERE A POTENTIAL LOW FORMS (AND ITS  
IMPLICATIONS FOR WINTER WEATHER ACROSS NC/VA). FOR NOW, THE NAM  
AND GFS WERE CONSIDERED LESS USEFUL AND NOT INCLUDED IN THE  
PREFERRED BLEND DUE TO ITS BIAS FOR DEEPER MOISTURE BEING PULLED  
BACK TO NW. THE BEST CONSENSUS APPROACH FAVORED THE 06Z GEFS MEAN  
AND 00Z ECMWF/ECENS MEAN. THOUGH IT'S IMPORTANT TO POINT OUT THAT  
THE DAY 3 FORECAST FOR THE SOUTHEAST IS A LOW CONFIDENCE FORECAST.  
  
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
TAYLOR  
  
  
 
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