173  
FXUS10 KWNH 010437  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1236 AM EDT WED JUL 01 2020  
 
VALID JUL 01/0000 UTC THRU JUL 04/1200 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
CLOSED LOW/TROUGH EXITING NEW ENGLAND BY THURSDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
MODEL GUIDANCE IS IN EXCELLENT AGREEMENT GRADUALLY TAKING THE  
UPPER LOW AND ASSOCIATED TROUGH AXIS OVER NEW ENGLAND GRADUALLY  
OFF TO THE EAST-SOUTHEAST OVER THE NEXT COUPLE OF DAYS AND  
ULTIMATELY OFFSHORE THE EAST COAST. THE 12Z CMC WAS SEEN AS BEING  
A BIT MORE PROGRESSIVE IN TIME AS THE ENERGY MOVES OUT TO SEA. THE  
REMAINING GUIDANCE IS WELL CLUSTERED SO A NON-CMC BLEND WILL BE  
PREFERRED.  
 
DEEP UPPER TROUGH/CLOSED LOW ACROSS THE INTERMOUNTAIN WEST  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z ECMWF  
CONFIDENCE: AVERAGE  
 
THE UPPER LOW/TROUGH IMPACTING THE NORTHERN INTERMOUNTAIN REGION  
WILL ADVANCE NORTH INTO SOUTHWEST CANADA ON WEDNESDAY AS ANOTHER  
SHORTWAVE TROUGH DROPS SOUTHWARD OVER THE PACIFIC NORTHWEST. THE  
PHASING OF THIS ENERGY WILL KEEP THE CLOSED LOW IN PLACE OVER  
SOUTHWEST CANADA MUCH OF THE PERIOD. HOWEVER, ANOTHER COMPACT  
CLOSED LOW AND ASSOCIATED TROUGH IS FORECAST TO DROP SOUTH DOWN  
THE COAST OF BRITISH COLUMBIA AND INTO THE PACIFIC NORTHWEST GOING  
THROUGH THURSDAY. THE MODELS GENERALLY SUPPORT TWO CLOSED LOWS  
THEN BY FRIDAY WITH ONE NEAR THE PACIFIC NORTHWEST AND ONE FARTHER  
NORTH OVER PARTS OF ALBERTA. THE 00Z NAM BY FRIDAY TENDS TO BE A  
BIT STRONGER WITH THE BROADER HEIGHT FALL EVOLUTION. THE 12Z CMC  
IS MOST OUT OF PHASE COMPARED TO THE OTHER MODELS AS IT LIFTS MORE  
ENERGY FARTHER NORTH THROUGH SOUTHWEST CANADA AND DOES NOT HAVE AS  
STRONG OF A TROUGH IMPACTING THE PACIFIC NORTHWEST BY THE END OF  
THE PERIOD. THERE ARE SOME MODEST SPATIAL/DEPTH DIFFERENCES WITH  
THE 00Z GFS, 12Z UKMET AND 12Z ECMWF, BUT THESE SOLUTIONS CLUSTER  
TOGETHER BETTER OVERALL, AND SO A BLEND OF THESE SOLUTIONS WILL BE  
PREFERRED.  
 
MCV CROSSING THE MIDWEST THROUGH WEDNESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
 
A CONVECTIVELY ENHANCED MCV SITUATED ALONG THE IA/IL BORDER, STUCK  
IN BETWEEN A DEEP LAYER RIDGE TO ITS SOUTH AND TO ITS NORTH IS  
FORECAST TO GRADUALLY DAMPEN AND SHEAR OUT OVER THE NEXT COUPLE OF  
DAYS WITH SOME OF THE REMNANT ENERGY DIGGING SOUTHEASTWARD AS THE  
RIDGE OVER THE GULF COAST STATES BREAKS DOWN AND ALLOWS A BROADER  
TROUGH TO ENVELOPE MUCH OF THE DEEP SOUTH AND INTERIOR OF THE  
SOUTHEAST. THE LATEST GUIDANCE GENERALLY AGREES WITH THIS  
SCENARIO, SO A GENERAL MODEL BLEND WILL AGAIN BE PREFERRED WITH  
THIS ENERGY.  
 
MID-LEVEL CLOSED LOW OVER THE GULF COAST BY FRIDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
MID-LEVEL TROUGHING AND A DEVELOPING CLOSED LOW OVER THE GULF  
COAST STATES IS EXPECTED BY THE END OF THE WEEK, WITH WEAK  
SHORTWAVE ENERGY DROPPING DOWN FROM THE MID-SOUTH. THERE IS DECENT  
AGREEMENT WITH THE LARGER SCALE MASS FIELD EVOLUTION AMONG THE  
MODELS, BUT THE 12Z UKMET BY THE END OF THE PERIOD IS NOTABLY  
WEAKER WITH ITS TROUGHING/CLOSED LOW. THE 00Z GFS ALSO MAY BE A  
TAD ON THE STRONG SIDE, BUT THERE IS SOME ENSEMBLE SUPPORT FOR  
THIS FROM THE LATEST GEFS MEAN, SO FOR NOW A NON-UKMET 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  
 
ORRISON  
 

 
 
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