079  
FXUS10 KWNH 051750  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
149 PM EDT THU SEP 05 2019  
 
VALID SEP 05/1200 UTC THRU SEP 09/0000 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: GFS/ECMWF/CMC BLEND  
CONFIDENCE: AVERAGE THROUGH 60 HOURS, BELOW AVERAGE FOR DAY 3  
 
THROUGH ABOUT 48-60 HOURS, THE GENERAL SYNOPTIC PATTERN ACROSS THE  
CONUS WILL FEATURE STRONG RIDGING ACROSS THE SOUTHWEST US AND  
SOUTHERN PLAINS WHILE A SHORTWAVE TROUGH APPROACHING THE NORTHEAST  
U.S. INTERACTS WITH DORIAN TO BE THE FINAL KICKER AS IT QUICKLY  
LIFTS OFFSHORE THE EASTERN U.S. AND INTO THE CANADIAN MARITIMES.  
FOR THIS PERIOD, MODEL GUIDANCE SHOW AVERAGE TO ABOVE AVERAGE RUN  
TO RUN AND MODEL TO MODEL CONSISTENCY SUCH THAT A GENERAL BLEND OF  
THE AVAILABLE GUIDANCE SHOULD SUFFICE ACROSS THE CONUS. THERE ARE  
SOME SUBTLE STRENGTH/TIMING DIFFERENCES NOTED WITH THE APPROACH OF  
THE GREAT LAKES AND NORTHEAST U.S. SHORTWAVE, PARTICULARLY THE  
SECONDARY SHORTWAVE THAT MOVES THROUGH ON SATURDAY. THE GFS/NAM  
ARE A BIT FASTER WHILE THE ECMWF/CMC ARE A TOUCH DEEPER.  
 
BEYOND 60 HOURS AND FURTHER WEST, THE MAIN CHALLENGES WILL BE A  
COUPLE OF SHORTWAVES AND A DEEPER TROUGH APPROACHING THE WESTERN  
U.S. COAST ON SATURDAY NIGHT INTO SUNDAY. THE BIG PICTURE IS IN  
GOOD AGREEMENT WITH ALL THE GUIDANCE SHOWING A TROUGH, BUT THE  
TYPICAL BIASES IN THE MODELS ARE PRESENT. THE GFS IS FASTER THAN  
MOST OF THE GUIDANCE WHILE THE UKMET IS DEEPER (MORE SOUTH) AND  
SLOWER, CLOSING OFF A LOW ACROSS SOUTHERN CALIFORNIA ON SUNDAY  
AFTERNOON.  
 
GIVEN THE RUN TO RUN VARIABILITY, THE PREFERENCE WOULD BE TO LEAN  
TOWARD THE PREVIOUS PREFERENCE SOMEWHAT AND GO WITH A GFS/ECMWF  
BLEND. THE CMC CAN ALSO BE INCORPORATED BUT PERHAPS TO A LESSER  
WEIGHT.  
 
   
..HURRICANE DORIAN
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PLEASE REFER TO THE OFFICIAL NATIONAL HURRICANE CENTER FORECAST  
TRACK. WITH THE LATEST (15Z) NHC ADVISORY, THERE IS GOOD AGREEMENT  
WITH THE LATEST MODEL SUITE THROUGH 48 HOURS AS DORIAN TAKES A  
NORTHEAST TURN AND BEGINS EXTRATROPICAL TRANSITION, INTERACTING  
WITH AN APPROACHING SHORTWAVE TROUGH FROM THE GREAT LAKES REGION.  
BEYOND 48 HOURS, THERE ARE SOME DIFFERENCES IN THE TRACK, WITH THE  
UKMET LEFT OF THE CURRENT ADVISORY TRACK AND THE LATEST GFS JUST A  
TAD EAST. A GENERAL MODEL BLEND, WITH A FOCUS ON THE  
GEFS/ECMWF/UKMET WILL SUFFICE.  
 
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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