395  
FXUS10 KWNH 140720  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
320 AM EDT SAT SEP 14 2019  
 
VALID SEP 14/0000 UTC THRU SEP 17/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
EXCEPTIONS: NON-UKMET IN PACIFIC NORTHWEST  
CONFIDENCE: ABOVE AVERAGE  
 
07Z UPDATE: THE 00Z UKMET STILL IS TOO PROGRESSIVE WITH THE  
SHORTWAVE OVER THE PACIFIC NORTHWEST THOUGH THE SPREAD IS LESS  
COMPARED TO THE PREVIOUS CYCLE. FOR NOW, WILL CONTINUE TO PREFER A  
NON-UKMET BLEND OVER THE PACIFIC NORTHWEST. OTHERWISE ACROSS THE  
REST OF THE CONUS, A GENERAL MODEL BLEND STILL IS SUFFICIENT.  
 
---PREVIOUS DISCUSSION---  
MOST OF THE ENERGY ACROSS THE CONUS WILL TRACK ALONG THE NORTHERN  
TIER OF THE US AND SOUTHERN CANADA WITH THE STRONGER CLOSED LOW  
OPENING UP AS IT CONTINUES LIFTING NORTH OF THE GREAT LAKES. A  
COMPACT SHORTWAVE TROUGH WILL SKIRT THE NORTHERN UPPER MIDWEST  
TODAY AND HERE MODEL AGREEMENT REMAINS WELL ABOVE AVERAGE SUCH  
THAT A GENERAL MODEL BLEND SHOULD BE MORE THAN SUFFICIENT.  
 
AN ANOMALOUSLY DEEP CLOSED UPPER LEVEL LOW THEN APPROACHES THE  
PACIFIC NORTHWEST LATE SATURDAY INTO SUNDAY. WHILE MODEL AGREEMENT  
HAS INCREASED IN THE LAST 2-3 CYCLES, THE 12Z UKMET STILL REMAINS  
THE FASTER OUTLIER COMPARED TO THE REST OF THE DETERMINISTIC  
MODELS. THE PREFERENCE FOR THIS CYCLE IS TO EXCLUDE THE UKMET BUT  
THE REST OF THE MODELS APPEAR IN GOOD AGREEMENT TO INCLUDE AT THIS  
TIME.  
 
ELSEWHERE ACROSS THE CONUS, LATEST GUIDANCE IN GOOD AGREEMENT  
SHOWING A SUBTLE SHORTWAVE TROUGH OVER THE SOUTHWEST US LIFTING  
NORTHWARD THROUGH DAY 2/3 AND GETTING ABSORBED INTO THE LARGE  
SCALE DEVELOPING TROUGH OVER THE ROCKIES. HERE, THE 12Z CMC OFFERS  
A GOOD COMPROMISE AND LIES NEAR THE CONSENSUS OF THE MODELS, WHERE  
THE GFS IS FASTER (EAST) COMPARED TO THE SLOWER (WEST) ECMWF.  
   
..TROPICAL STORM HUMBERTO
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: OFFICIAL NHC FORECAST  
BEST PROXY: 12Z ECMWF/00Z NAM THROUGH 24-36 HOURS; THEN CONSENSUS  
OF AVAILABLE GUIDANCE  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
 
THE LATEST TRENDS IN THE FORECAST GUIDANCE SHIFT THE TRACK OF NOW  
TROPICAL STORM HUMBERTO EAST, GENERALLY AWAY FROM THE FL AND  
SOUTHEAST US COASTLINE. BASED ON THE INITIAL 00Z GUIDANCE  
(GFS/NAM) AND 12Z NON-NCEP GUIDANCE, THE LATEST (03Z) OFFICIAL NHC  
TRACK LIES NEAR THE CONSENSUS OF THE AVAILABLE GUIDANCE. THE GFS  
TRACKS GENERALLY TO THE LEFT (WEST) WHILE THE ECMWF/UKMET LIE TO  
THE RIGHT (EAST). THE NAM AND TO SOME DEGREE THE 12Z ECMWF ARE A  
FAIRLY GOOD PROXY TO THE OFFICIAL TRACK, THOUGH NO MODEL AGREES  
WITH THE OFFICIAL TRACK THROUGHOUT THE NEXT 84 HOURS. THE SPREAD  
INCREASES CONSIDERABLY BEYOND 48 HOURS SUCH THAT THE FORECAST  
CONFIDENCE IS BELOW AVERAGE TO SLIGHTLY BELOW AVERAGE.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
TAYLOR  
 

 
 
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