465  
FXUS10 KWNH 101655  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1254 PM EDT WED JUN 10 2020  
 
VALID JUN 10/1200 UTC THRU JUN 14/0000 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z PRELIMINARY MODEL EVALUATION INCLUDING PREFERENCES AND  
CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
...SHORTWAVE AND ASSOCIATED SURFACE LOW LIFTING INTO CANADA  
TONIGHT...  
...DEEPENING EASTERN CONUS TROUGH AND COLD FRONT THROUGH FRIDAY  
NIGHT...  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL BLEND THROUGH FRIDAY  
ECENS/GEFS D3  
CONFIDENCE: AVERAGE  
 
THROUGH FRIDAY, THE GLOBAL MODELS ARE IN VERY GOOD AGREEMENT IN  
THE EVOLUTION OF A WEAKENING SHORTWAVE AND ASSOCIATED SURFACE LOW  
LIFTING THROUGH THE UPPER MIDWEST AND INTO CANADA, SO A GENERAL  
MODEL BLEND IS REASONABLE. LATE FRIDAY AND SATURDAY, THE NORTHEAST  
GETS VERY MESSY AS 4 INDIVIDUAL SHORTWAVES INTERACT IN SOME  
FASHION ACROSS SOUTHEAST CANADA. THESE WILL LIKELY CONGEAL INTO A  
LARGER CLOSED LOW/GYRE WHICH WILL THEN AMPLIFY A LONGWAVE TROUGH  
ACROSS THE EASTERN CONUS. THERE IS LITTLE AGREEMENT IN THE  
DETERMINISTIC MODELS INTO D3 AS TO HOW THIS WILL EVOLVE, ALTHOUGH  
THE ECMWF IS A CLEAR STRONG OUTLIER, WHILE THE GFS IS BY FAR THE  
MOST PROGRESSIVE. WITHOUT ANY CLEAR INDICATOR AS TO WHICH  
SHORTWAVE WILL BECOME DOMINANT, WHICH WOULD LEAD TO A MORE  
DEFINITIVE EVOLUTION OF THE TROUGH AMPLIFICATION, FEEL A BLEND  
TOWARDS THE GEFS/ECENS MEANS IS MOST REASONABLE. THIS WILL WASH  
OUT SOME OF THE FINER PRECIP DETAILS, ESPECIALLY ALONG THE  
SOUTHEAST COAST WHERE THE STALLING FRONT COULD FIRE CONVECTION,  
BUT FOR AMPLITUDE AND PLACEMENT OF THE MEAN TROUGH PREFER TO HEDGE  
TOWARDS THE MEANS DUE TO WIDELY VARYING DETERMINISTIC SOLUTIONS AT  
THIS TIME.  
 
...LONGWAVE TROUGH OFF THE WEST COAST AND SHORTWAVE LIFTING  
ONSHORE CALIFORNIA BY THE WEEKEND...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON GFS THROUGH D2, NON GFS OR CMC D3  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
 
THE GUIDANCE IS BECOMING AT LEAST SOMEWHAT BETTER ALIGNED WITH A  
SUBTLY MORE PROGRESSIVE SOLUTION INTO THE WEST COAST. THE  
IMPORTANT SHORTWAVE ROTATING THROUGH THE BASE OF THE LONGWAVE  
TROUGH EXTENDING FROM A CLOSED LOW OFF THE BC COAST WILL TILT  
NEGATIVELY AND LIFT ONSHORE LATE FRIDAY INTO SATURDAY. THERE  
REMAIN TIMING DIFFERENCES OF THIS FEATURE, MOST NOTABLY THE GFS  
CONTINUES TO BE THE FASTEST WITH THE EJECTION OF THE SHORTWAVE TO  
THE NORTHEAST. THE GEFS MEAN IS ALSO ON THE FAST EDGE OF THE  
ENSEMBLE CLUSTER. HOWEVER, SINCE THE OTHER GUIDANCE HAS SPED UP AT  
LEAST SOMEWHAT, USING THE GEFS MEAN IS REASONABLE THROUGH 60  
HOURS. THEREAFTER, THE CMC BECOMES A STRONG OUTLIER WITH THE  
AMPLITUDE OF THE SHORTWAVE AS IT PIVOTS INTO THE GREAT BASIN  
SATURDAY, LEAVING THE ECENS/ECMWF/NAM/UKMET/GEFS AS THE PREFERRED  
BLEND.  
 
WEISS  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 

 
 
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