432  
FXUS10 KWNH 191653  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1252 PM EDT FRI JUN 19 2020  
 
VALID JUN 19/1200 UTC THRU JUN 23/0000 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION INCLUDING PRELIMINARY PREFERENCES AND  
FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
EASTERN U.S. CLOSED LOW AND COASTAL FRONT  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
OVERALL, THE DETERMINISTIC GUIDANCE IS NOW IN GOOD AGREEMENT WITH  
THIS SYSTEM -- INDICATING A CLOSED LOW DEVELOPING PERIODICALLY AS  
IT MOVES FROM THE OHIO VALLEY TO THE MID-ATLANTIC STATES FRIDAY  
AND SATURDAY, BEFORE LIFTING OFF OF THE MID-ATLANTIC TO THE NEW  
ENGLAND COASTS SUNDAY AND MONDAY.  
 
CLOSED LOW DEVELOPING OVER NORTHERN HIGH PLAINS AND PARADE OF  
SHORTWAVES ACROSS CENTRAL PLAINS  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-GFS BLEND  
CONFIDENCE: AVERAGE  
 
OVERALL, THE DETERMINISTIC GUIDANCE IS IN GOOD AGREEMENT THROUGH  
LATE SATURDAY. BY SUNDAY MORNING HOWEVER, THE GFS BECOMES MORE OF  
AN OUTLIER -- ESPECIALLY WITH THE UPPER LEVEL SHORTWAVE AND  
ASSOCIATED SURFACE LOW LIFTING FROM THE MID MISSISSIPPI VALLEY  
INTO THE GREAT LAKES. THE GFS SHOWS A MORE AMPLIFIED UPPER LEVEL  
TROUGH AND SLOWER SURFACE REFLECTION THAN MOST GUIDANCE.  
DIFFERENCES CONTINUE AS THIS SYSTEM LIFTS NORTH OF THE GREAT LAKES  
INTO CANADA AND INTERACTS WITH THE UPPER LOW OVER CENTRAL CANADA.  
THE GFS SHOWS LESS INTERACTION BETWEEN THE SYSTEM WITH A WEAKER  
SHORTWAVE LIFTING NORTH OF THE GREAT LAKE TOWARD JAMES BAY WHILE  
MAINTAINING A DEEP LOW OVER MANITOBA AND WESTERN ONTARIO ON  
MONDAY. MOST GUIDANCE SHOWS THE SHORTWAVE OVER THE GREAT LAKES  
AMPLIFYING, WITH A CLOSED LOW DEVELOPING NEAR JAMES BAY AS THE  
SYSTEM TO WEST GRADUALLY WEAKENS.  
 
TROUGHS APPROACHING THE PACIFIC NORTHWEST THROUGH SUNDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-GFS BLEND  
CONFIDENCE: AVERAGE  
 
WITH THE SHORTWAVE MOVING FROM THE PACIFIC NORTHWEST TO THE  
NORTHERN HIGH PLAINS ON SUNDAY, THE GFS IS MORE AMPLIFIED THAN THE  
OTHER DETERMINISTIC MODELS. OTHERWISE, MODELS SHOW GENERALLY GOOD  
AGREEMENT THROUGH THE PERIOD.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
PEREIRA  
 

 
 
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