182  
FXUS10 KWNH 311938  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
338 PM EDT SAT AUG 31 2019  
 
VALID AUG 31/1200 UTC THRU SEP 04/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION, CONFIDENCE, AND PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
19Z UPDATE: WITH THE REST OF THE 12Z GUIDANCE AVAILABLE, IT  
APPEARS THAT THE 12Z CMC TRENDED MORE TOWARD THE REST OF THE MODEL  
SOLUTIONS WITH THE NORTHERN U.S. SHORTWAVE ON DAY 3. AS A RESULT,  
ITS SOLUTION CAN BE INCORPORATED WITH THE MODEL PREFERENCE BLEND.  
NO OTHER SIGNIFICANT DIFFERENCES WERE NOTED ACROSS THE REMAINDER  
OF THE CONUS THROUGH 84 HOURS.  
 
---PREVIOUS DISCUSSION---  
THE GENERAL SYNOPTIC PATTERN ACROSS THE CONUS IS EXPECTED TO  
FEATURE TROUGHING OVER THE GREAT LAKES AND EASTERN U.S. WITH  
BUILDING RIDGING OVER THE SOUTHWEST U.S. THROUGH THE NEXT 84  
HOURS. A STRONGER SHORTWAVE TROUGH WILL SWING THROUGH THE NORTHERN  
ROCKIES INTO THE NORTHERN PLAINS BY EARLY NEXT WEEK. IN THE LARGE  
SCALE SENSE, MOST OF THE LATEST OPERATIONAL AND DETERMINISTIC  
GUIDANCE IS IN GOOD AGREEMENT. THE 00Z CMC DIGS THE NORTHERN TIER  
SHORTWAVE TOO MUCH BEYOND 48 HOURS WHILE THE 12Z NAM IS A BIT TOO  
AMPLIFIED AS WELL. THE EARLIER BIAS SEEN IN THE GFS BEING TOO FAST  
SEEMS TO HAVE RESOLVED ITSELF THIS CYCLE SUCH THAT IT CAN BE  
INCORPORATED MORE.  
 
OVERALL, A NON-NAM, NON-CMC BLEND WOULD SUFFICE FOR THE MASS  
FIELDS ACROSS THE REST OF THE CONUS. FOR THE LATEST MODEL  
PREFERENCE AND TRACK PROXY FOR DORIAN, SEE BELOW.  
 
   
..HURRICANE DORIAN  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PLEASE REFER TO THE OFFICIAL NATIONAL HURRICANE CENTER FORECAST  
TRACK  
 
INITIALLY, THE GUIDANCE THAT ALIGNS WITH THE LATEST OFFICIAL NHC  
FORECAST TRACK IS A CONSENSUS/BLEND OF THE 06Z GEFS, 12Z NAM, AND  
12Z GFS (THROUGH 60 HOURS). BEYOND THAT TIME FRAME, THE FORECAST  
TRACK LIES NEAR THE MIDDLE OF THE DETERMINISTIC AND OPERATIONAL  
CONSENSUS. THE CMC IS MUCH FASTER COMPARED TO THE REST OF THE  
GUIDANCE AND THE UKMET IS SLOWER AND TO THE SOUTHWEST. PAST 60  
HOURS, THE GFS/NAM ARE ON THE EASTERN FRINGE OF THE MODEL SPREAD  
WHILE THE ECMWF, WHILE SLOWER, IS A DECENT PROXY AS WELL.  
 
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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