947  
FXUS10 KWNH 170631  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
231 AM EDT FRI AUG 17 2018  
 
VALID AUG 17/0000 UTC THRU AUG 20/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION...WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL SYNOPTIC PATTERN ACROSS THE CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF 00Z ECMWF, 00Z CMC, 00Z GFS  
CONFIDENCE: AVERAGE  
 
---06Z UPDATE---  
NO CHANGE TO THE PRELIMINARY PREFERENCES OR REASONING. THE 00Z  
UKMET, CMC AND ECMWF WERE FAIRLY CONSISTENT WITH THEIR PRIOR RUNS.  
THE UKMET DID TREND SLIGHTLY TOWARD THE CONSENSUS.  
 
---PREVIOUS DISCUSSION---  
OVER THE NEXT FEW DAYS, THE ECMWF, CMC AND GFS OFFER DECENT  
AGREEMENT AND ALL THREE DETERMINISTIC MODELS ARE CONTAINED WELL  
WITHIN THE ENSEMBLE SPREAD ENVELOPE FOR THEIR VARIOUS MASS FIELDS.  
GREATER DIFFERENCES BEGIN TO EMERGE JUST BEYOND THE TIME PERIOD  
THAT IS THE SCOPE OF THIS DISCUSSION, INTO NEXT WEEK, AS A SURFACE  
LOW BEGINS TO TAKE SHAPE IN THE MIDWEST. NEVERTHELESS, IN THIS  
TIME PERIOD, THEY ARE CLOSE ENOUGH THAT A BLEND OF THE THREE IS  
PREFERRED. THE 00Z NAM SHOWS A NOTABLY FASTER PROGRESSION AND  
DIGGING WITH THE TROUGH PUSHING INTO THE WEST COAST ON SUNDAY. IT  
IS ALSO OUT OF PHASE WITH THE NORTHEAST TROUGH AS COMPARED TO THE  
OTHER MODELS. THE 12Z UKMET SHOWS BETTER ALIGNMENT WITH THE  
TROUGHS AND RIDGES, BUT ITS HEIGHTS ARE NOTABLY HIGHER EAST OF THE  
ROCKIES BY SUNDAY, AND OCCASIONALLY NEAR THE OUTER EXTENT OF THE  
ENSEMBLE SPREAD ENVELOPE. THEREFORE, THE NAM AND UKMET WERE  
EXCLUDED FOR THESE REASONS.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
LAMERS  
 

 
 
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