135  
FXUS10 KWNH 130812  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
411 AM EDT TUE AUG 13 2019  
 
VALID AUG 13/0000 UTC THRU AUG 16/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z FINAL MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GEFS MEAN/12Z ECENS MEAN  
CONFIDENCE: BELOW AVERAGE  
 
THE GENERAL PATTERN EVOLUTION IS OF ZONAL FLOW BECOMING A WESTERN  
RIDGE AND AN EASTERN TROUGH OVER THE NEXT FEW DAYS. THIS IS WELL  
AGREED UPON BY MOST GLOBAL GUIDANCE. HOWEVER, THE SMALL SCALE  
FEATURES REMAIN QUITE UNCERTAIN, AND THIS IS CONTINUING A LOWER  
THAN AVERAGE CONFIDENCE FORECAST IN THE PREFERRED BLEND.  
 
THE UKMET REMAINS A STRONG OUTLIER WITH ITS HEIGHTS BOTH WITHIN  
THE DEVELOPING WESTERN RIDGE AND THE EASTERN TROUGH (WEAKER TROUGH  
DESPITE A STRONGER RIDGE). WHILE THE REMAINING GUIDANCE HAS  
TRENDED A BIT MORE AMPLIFIED WITH THE 500 PATTERN, THE UKMET IS  
STILL SEVERAL DM OUT OF TOLERANCE WITH THE GLOBAL CONSENSUS, WITH  
LITTLE IN THE WAY OF ENSEMBLE SUPPORT.  
 
ON THE SMALLER SCALE, SEVERAL SHORTWAVES, SOME OF WHICH ARE LIKELY  
TO BE CONVECTIVELY REINFORCED AND HAVE LITTLE FORECAST SKILL ON  
LARGE SPATIAL SCALES AT DISTANT TIMRANGES, WILL ROTATE ATOP THE  
RIDGE THROUGH GENERALLY ZONAL FLOW BEFORE DROPPING INTO THE TROUGH  
THE MIDDLE OF THE WEEK. THE NAM REMAINS STRONG WITH MUCH OF THIS  
ENERGY COMPARED TO THE REMAINING GUIDANCE, WHILE THE CMC IS AGAIN  
SEVERAL DEGREES OF LONGITUDE TOO FAST WITH THESE IMPULSES, AS WELL  
AS A MORE SIGNIFICANT FEATURE DROPPING INTO THE PACNW THURSDAY,  
DESPITE CONSIDERABLE MODEL SPREAD.  
 
THIS AGAIN LEAVES JUST THE ECMWF AND GFS, BOTH OF WHICH ARE  
EXPERIENCING THEIR OWN SET OF ISSUES WITH MINIMAL CONSISTENCY IN  
QPF/FRONTAL PLACEMENT ON DAY 3. THE MEANS OF THE GEFS AND ECENS  
AGAIN APPEAR TO BE THE BEST SOLUTION AT THIS TIME, BOTH FOR  
CONSISTENCY, BUT TO ALSO REMOVE SOME OF THE FINE DETAILS THAT  
STRUGGLE TO BE RESOLVED IN THE FORECAST. WHILE THESE SMALL DETAILS  
WILL BE IMPORTANT, THEY ARE BEST RESERVED FOR A SHORTER-TERM  
FORECAST (IE DAY 1) AND IT IS SUGGESTED THE MEANS BE USED  
EXCLUSIVELY BEYOND 24 HOURS.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
WEISS  
 
 
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