564  
FXUS10 KWNH 040440  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1239 AM EDT SAT JUL 4 2020  
 
VALID JUL 4/0000 UTC THRU JUL 7/1200 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
TROUGH BUILDING OVER THE NORTHEAST U.S. THIS WEEKEND  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH SUNDAY AFTERNOON, THEN  
NON-UKMET BLEND  
CONFIDENCE: MODERATE-HIGH  
 
A PAIR OF SHORTWAVE TROUGHS ARE EXPECTED TO MOVE THROUGH THE  
NORTHEAST OVER THE NEXT FEW DAYS, WITH THE FIRST ARRIVING BY  
SATURDAY MORNING. A GENERAL MODEL BLEND FOR MASS FIELD PURPOSES  
IS SUFFICIENT HERE. A SECOND SHORTWAVE TROUGH THEN ARRIVES BY  
LATE SUNDAY, AND IS EXPECTED TO CLIP THE NORTHERN AREAS OF THE  
NORTHEAST AND ACROSS NEW ENGLAND. THE CMC, GFS, AND UKMET ARE  
MORE AMPLIFIED WITH THIS TROUGH AS IT CROSSES THE REGION AND THEN  
OFFSHORE, WITH THE UKMET INDICATING THE SLOWEST SOLUTION.  
 
TROUGH OVER THE GULF COAST REGION  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GFS/ECMWF BLEND  
CONFIDENCE: MODERATE  
 
A SLIGHT WEAKNESS IN THE UPPER LEVEL RIDGE ANCHORED OVER THE  
CENTRAL/SOUTHERN PLAINS EXPANDS FURTHER DURING THE COURSE OF THE  
PERIOD AS SEVERAL CONVECTIVELY ENHANCED MCVS SETTLE OVER THE LOWER  
MS RIVER VALLEY AND GULF COAST REGION (WHILE THE RIDGE UPSTREAM  
RETREATS TO THE SOUTHWEST U.S.). THE SYNOPTIC PATTERN IS LARGELY  
AGREEABLE THOUGH THE UKMET IS A LITTLE STRONGER WITH THE UPPER  
RIDGE COMPARED TO THE OTHER GUIDANCE. THE ECMWF AND GFS ARE CLOSE  
ENOUGH TO THEIR RESPECTIVE MEANS TO MERIT A BLEND OF THOSE TWO  
MODELS.  
 
PAIR OF TROUGHS AFFECTING THE NORTHWESTERN U.S.  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GFS/ECMWF BLEND  
CONFIDENCE: MODERATE  
 
THE FLOW PATTERN ACROSS THE NORTHWESTERN QUADRANT OF THE NATION IS  
EXPECTED TO REMAIN ACTIVE AS A LARGE SCALE TROUGH REMAINS IN PLACE  
ACROSS THE REGION. THE FIRST SHORTWAVE TRACKING ACROSS THE  
PACIFIC NORTHWEST ON SATURDAY IS EXPECTED TO REACH MANITOBA BY  
MONDAY MORNING, AND THIS WILL SUPPORT A COLD FRONT CROSSING THE  
NORTHERN HIGH PLAINS. THE MODELS ARE IN DECENT AGREEMENT WITH  
THIS FIRST SYSTEM. A SECOND SHORTWAVE REACHES THE PACIFIC  
NORTHWEST BY MONDAY AFTERNOON AS THE OVERALL PATTERN AMPLIFIES  
SOME. THE GFS IS SLIGHTLY FASTER AND THE CMC IS A BIT SLOWER, AND  
A STRONGER SOLUTION WITH THE UKMET BY TUESDAY MORNING. AS A  
COMPROMISE AND CONSENSUS, A BLEND OF THE GFS/NAM/ECMWF IS  
PREFERRED.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
HAMRICK  
 

 
 
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