136  
FXUS10 KWNH 260405  
PMDHMD  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1204 AM EDT MON AUG 26 2019  
 
VALID AUG 26/0000 UTC THRU AUG 29/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE THROUGH 60HRS SLIGHTLY ABOVE AVERAGE  
AFTER  
EXCEPTION: 00Z GFS/NAM W/UKMET/GEFS/ECENS AT LOWER WEIGHT (COASTAL  
LOW)  
 
THE 00Z NAM/GFS CONTINUED ANOTHER CYCLE OF CONSISTENCY AND STRONG  
DETERMINISTIC GUIDANCE AGREEMENT WITH THE SYNOPTIC  
PATTERN/EVOLUTION OVER THE CONUS. AS WITH ANY RUN, THERE ARE  
SOME VERY SMALL SCALE AMPLITUDE DIFFERENCES, AS WELL AS,  
DIFFERENCES DUE TO CONVECTIVE DEVELOPMENT/FEEDBACK. THE LARGEST  
DIFFERENCES IN THE MASS FIELDS/QPF AXES, ARE DRIVEN BY SLIGHT  
TIMING DIFFERENCES WITH THE FRONTAL ZONE CROSSING THE NORTHEAST  
AND THE INTERACTION WITH THE MOISTURE FEED FROM THE THE  
TROPICAL/SUBTROPICAL SURFACE WAVE TO THE SOUTHEAST WED INTO THURS.  
THE UKMET IS A BIT FASTER AND IT ALONG WITH THE 00Z NAM SUGGEST  
SLIGHTLY EARLIER DEEP MOISTURE FLUX FOR SOME HEAVY RAINFALL ACROSS  
SE ME. THIS IS INTERESTING, GIVEN THE SPACING BETWEEN THE UKMET  
AND NAM IS PROBABLY THE LARGEST SPREAD WITH THE SURFACE WAVE, AND  
THE UKMET IS STRONGER THAN THE NAM. OVERALL, THE DEEP CLOSED LOW  
IN S CANADA AND THE FRONTAL ZONE SPREAD IS SMALL ENOUGH TO SUPPORT  
A GENERAL MODEL BLEND, BUT THE SURFACE WAVE OFF THE COAST HAS  
MODERATE SPREAD. THE ECMWF HAS ONCE AGAIN BECOME FAST AND STRONG,  
PAIRED CLOSEST TO THE UKMET, WHILE THE GFS AND NAM ARE WEAKEST AND  
DRAW WESTWARD DUE TO THE APPROACHING HEIGHT-FALLS. THE CMC ALSO  
BENDS LEFT BUT IS VERY STRONG BY THE END OF DAY 3, WHICH DOES NOT  
SEEM A GOOD FIT TO CONTINUITY AND THE ENSEMBLE SUITE. OVERALL  
WOULD FAVOR A NAM/GFS SOLUTION WITH SOME LOWER WEIGHTED UKMET AND  
SOME ECENS/GEFS MEAN IN THE BLEND.  
 
ELSEWHERE, THERE IS A SMALL TIMING ISSUE WITH A STRONG SHORTWAVE  
ACROSS NW CANADA ON DAY 3. THE 00Z NAM AND 12Z UKMET ARE TOO  
FAST, THOUGH WITH LITTLE SENSIBLE AFFECT TO EVEN THE NORTHERN TIER  
OF THE CONUS, BUT WOULD SHADE AWAY FROM THOSE IN A LARGER SCALE  
BLEND. SO OVERALL A GENERAL MODEL BLEND IS SUPPORTED, WITH ONLY  
EXCEPTIONS NOTED ABOVE, WITH AN ABOVE AVERAGE CONFIDENCE THROUGH  
ABOUT 60HRS BEFORE REDUCING TO SLIGHTLY ABOVE AVERAGE AFTERWARD.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
GALLINA  
 

 
 
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