415  
FXUS10 KWNH 251636  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1235 PM EDT SAT JUL 25 2020  
 
VALID JUL 25/1200 UTC THRU JUL 29/0000 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..MID-UPPER LEVEL TROUGHING OVER THE NORTHERN CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
A MID TO UPPER-LEVEL TROUGH OVER THE NORTHWEST AND ADJACENT AREAS  
OF SOUTHWEST CANADA WILL ADVANCE EAST THROUGH EARLY NEXT WEEK AND  
GRADUALLY AMPLIFY OVER PORTIONS OF THE MIDWEST AND GREAT LAKES  
REGION GOING THROUGH TUESDAY. IN FACT, ALL OF THE MODELS SHOW A  
WELL-DEVELOPED UPPER LOW JUST TO THE NORTH OVER ONTARIO BY THE END  
OF THE PERIOD. THE MODEL GUIDANCE IS REASONABLY WELL CLUSTERED  
WITH THE TIMING AND EVOLUTION OF THIS ENERGY ALONG WITH THE  
ATTENDANT COLD FRONT CROSSING PORTIONS OF THE PLAINS, MIDWEST AND  
EVENTUALLY THE EASTERN U.S. SO, A GENERAL MODEL BLEND WILL AGAIN  
BE PREFERRED.  
 
   
..HURRICANE HANNA
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: OFFICIAL NHC TRACK  
BEST MODEL PROXY: 12Z NAM/GFS BLEND  
CONFIDENCE: SEE LATEST NHC PRODUCTS  
 
HURRICANE HANNA WILL MAKE LANDFALL ALONG THE SOUTH TEXAS COAST  
THIS AFTERNOON AND ACROSS DEEP SOUTH TEXAS TONIGHT BEFORE CROSSING  
INTO NORTHEAST MEXICO EARLY ON SUNDAY. THE 12Z NAM/GFS SOLUTIONS  
APPEAR GENERALLY TO BE THE CLOSEST TO THE 15Z NHC FORECAST TRACK.  
THE 00Z UKMET BECOMES A BIT OF A FASTER OUTLIER SOLUTION BY THIS  
EVENING AND OVERNIGHT AND IS ALSO A BIT SOUTH OF THE NHC TRACK.  
THE 00Z CMC/ECMWF SOLUTIONS ARE BOTH JUST A LITTLE FASTER AND A  
TAD NORTH OF THE NHC TRACK. FOR THE LATEST INFORMATION ON HANNA,  
PLEASE CONSULT THE LATEST NHC PUBLIC ADVISORY.  
 
   
..UPPER TROUGH/LOW OVER CALIFORNIA/GREAT BASIN
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
A BROAD UPPER TROUGH AND EMBEDDED CLOSED LOW OVER CA WILL  
GENERALLY REMAIN IN PLACE OVER THE NEXT COUPLE OF DAYS, BUT SHOULD  
THEN GRADUALLY ADVANCE NORTHEAST AND WEAKEN THROUGH THE GREAT  
BASIN BY TUESDAY. OVERALL, THE MODELS ARE IN GOOD AGREEMENT  
THROUGH THE PERIOD WITH THE HANDLING OF THIS ENERGY, SO A GENERAL  
MODEL BLEND WILL BE PREFERRED.  
 
   
..NEW UPPER TROUGH/LOW APPROACHING CALIFORNIA BY TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
A NEW UPPER TROUGH AND EMBEDDED CLOSED LOW WILL BE APPROACHING CA  
BY LATE TUESDAY. THE 00Z CMC IS A PROGRESSIVE OUTLIER WITH THIS  
ENERGY. THE REMAINING GUIDANCE IS SLOWER AND AGREES IN STILL  
HAVING THE BULK OF THE ENERGY OFFSHORE AT LEAST THROUGH THIS  
PERIOD, SO A NON-CMC BLEND WILL BE PREFERRED.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
THIS PRODUCT WILL TERMINATE AUGUST 15, 2020:  
WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN20-58PMDHMD_TERMINATION.  
PDF  
 
ORRISON  
 

 
 
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