186  
FXUS10 KWNH 041854  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
254 PM EDT FRI OCT 04 2019  
 
VALID OCT 04/1200 UTC THRU OCT 08/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND...NORTHWEST AND NORTHEAST U.S.  
12Z GFS/UKMET/ECMWF BLEND...PLAINS/MIDWEST  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE LARGE SCALE FLOW PATTERN ACROSS THE CONUS OVER THE NEXT FEW  
DAYS WILL FEATURE MULTIPLE PROGRESSIVE NORTHERN STREAM TROUGHS.  
THIS WILL CONSIST OF A TROUGH EARLY IN THE PERIOD ACROSS THE  
NORTHEAST WHICH WILL ADVANCE QUICKLY EAST ACROSS PORTIONS OF  
SOUTHEAST CANADA AND THE OFFSHORE WATERS TONIGHT THROUGH SATURDAY.  
MEANWHILE, A STRONG UPPER TROUGH ALREADY ADVANCING INLAND ACROSS  
THE GREAT BASIN AND THE NORTHERN ROCKIES WILL MOVE EAST ACROSS THE  
PLAINS AND MIDWEST THROUGH SATURDAY WHILE TAKING ON A NEGATIVE  
TILT. THIS WILL DRIVE CYCLOGENESIS IN THE LEE OF THE ROCKIES WHICH  
WILL ADVANCE NORTHEAST ACROSS THE UPPER MIDWEST AND WESTERN GREAT  
LAKES REGION. BY LATER AND SUNDAY AND MONDAY, THE GUIDANCE  
INDICATES A NEW TROUGH THEN BEGINNING TO AMPLIFY DOWN TOWARD THE  
NORTHWEST U.S. AS THE TROUGH OVER THE PLAINS/MIDWEST WEAKENS A BIT  
AND MOVES DOWNSTREAM ACROSS THE REMAINDER OF THE GREAT LAKES  
REGION AND THE OH VALLEY.  
 
THE MODELS ARE IN VERY GOOD AGREEMENT WITH THE MASS FIELD  
EVOLUTION OF THE HEIGHT FALLS EXITING THE NORTHEAST AND WITH THE  
NEW TROUGH DIGGING TOWARD THE NORTHWEST BY EARLY NEXT WEEK, BUT  
THERE ARE DIFFERENCES WITH THE DETAILS OF THE TROUGHING CROSSING  
THE PLAINS AND MIDWEST. THE 12Z GFS APPEARS TO BE A BIT TOO  
ENERGETIC WITH ITS CLOSED MID-LEVEL LOW CIRCULATION OVER THE  
DAKOTAS WHICH IS DRIVING A STRONGER SURFACE LOW COMPARED TO THE  
REMAINING GUIDANCE. HOWEVER, OVERALL, THE 12Z NAM AND TO SOME  
EXTENT THE 12Z CMC ARE POSSIBLY A TAD TOO WEAK. THE LATEST  
ENSEMBLE MEANS FAVOR A SOLUTION GENERALLY A LITTLE STRONGER THAN  
THE NAM/CMC CAMP AND CLOSER TO THE 12Z UKMET/ECMWF SOLUTIONS AT  
LEAST THROUGH 60 HOURS. THEREAFTER AS THE ENERGY DAMPENS OUT AND  
MOVES FURTHER EAST, THE GFS COMES INTO BETTER AGREEMENT WITH THE  
MULTI-MODEL CONSENSUS.  
 
A GENERAL MODEL BLEND WILL BE PREFERRED ACROSS THE NORTHEAST AND  
THE NORTHWEST, BUT A BLEND OF THE GFS, UKMET, AND ECMWF WILL BE  
PREFERRED WITH THE TROUGH ACROSS THE PLAINS AND MIDWEST.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 
 
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