074  
FXUS10 KWNH 301937  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
336 PM EDT FRI AUG 30 2019  
 
VALID AUG 30/1200 UTC THRU SEP 03/0000 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: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
19Z UPDATE:  
LITTLE CHANGE NOTED WITH THE REST OF THE 12Z GUIDANCE NOW  
AVAILABLE. ACROSS THE NORTHERN TIER OF THE U.S., THE MAIN  
DIFFERENCES WERE SEEN IN THE NORTHERN ROCKIES SHORTWAVE ON DAY 3.  
THE 12Z REMAINED THE FASTER/FLATTER OUTLIER COMPARED TO THE OTHER  
GUIDANCE.  
 
---PREVIOUS DISCUSSION---  
THE SYNOPTIC PATTERN OVER THE CONUS THROUGH THE NEXT 3 DAYS IS  
EXPECTED TO FAVOR GENERAL TROUGHING OVER THE GREAT LAKES REGION  
WITH SOME RIDGING THROUGH THE INTER-MOUNTAIN WEST AND NORTHERN  
ROCKIES. TOWARD THE END OF DAY 3, ANOTHER SHORTWAVE TROUGH  
APPROACHES THE PACIFIC NORTHWEST WHILE RIDGING BUILDS MORE OVER  
THE SOUTHWEST U.S. A COMPACT SHORTWAVE WILL DROP THROUGH THE  
LONGWAVE TROUGHING OVER THE CENTRAL/EASTERN U.S., HELPING TO  
REINFORCE THE TROUGH OVER THE NORTHEAST.  
 
OVERALL, MODEL AGREEMENT IS ABOVE AVERAGE DURING THE FORECAST  
PERIOD WITH RELATIVELY MINOR SPREAD SEEN IN THE DETERMINISTIC  
GUIDANCE AND WITHIN THE ENSEMBLE SPREAD. THE NAM, AS TYPICAL, IS  
TOO AMPLIFIED WITH THE PACIFIC NORTHWEST SHORTWAVE BY DAY 3, AND  
THE LATEST GFS IS A BIT FASTER WITH ITS PROGRESSION ACROSS THE  
NORTHERN PLAINS.  
 
THE PREFERENCE THIS CYCLE IS FOR A GENERAL MODEL BLEND, ACCOUNTING  
FOR THE TYPICAL BIASES.  
 
   
..HURRICANE DORIAN
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PLEASE REFER TO THE OFFICIAL NATIONAL HURRICANE CENTER FORECAST  
TRACK  
 
THE LATEST FORECAST INFORMATION FOR HURRICANE DORIAN IS MOST  
ALIGNED WITH THE 00Z ECMWF/CMC THROUGH 84 HOURS. MODEL SPREAD  
INCREASES BEYOND THAT PERIOD, BUT THE ECMWF/CMC FALLS IN THE  
MIDDLE OF THE MODEL ENVELOPE AT THIS TIME.  
 
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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