713  
FXUS10 KWNH 190703  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
302 AM EDT TUE SEP 19 2017  
 
VALID SEP 19/0000 UTC THRU SEP 22/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION...WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..INITIAL CLOSED LOW APPROACHING THE PACIFIC NORTHWEST
 
   
..UPPER TROUGH SWEEPING ACROSS THE NORTHWEST THROUGH TUES
 
   
..ASSOCIATED COLD FRONT EJECTING OUT INTO THE PLAINS TUES-WED
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-GFS CONSENSUS  
CONFIDENCE: AVERAGE  
 
THE MODEL DIFFERENCES WITH THE NEXT SURGE OF HEIGHT  
FALLS/TROUGHING DROPPING DOWN ACROSS THE NORTHWEST ARE NOT AS  
SIGNIFICANT AS 24 HOURS AGO...BUT THE 00Z GFS CONTINUES TO SUPPORT  
A STRONGER CLOSED LOW EVOLUTION OVER SOUTHERN CANADA AS THE  
INITIAL SURGE OF HEIGHT FALLS PIVOT ACROSS THE NORTHERN ROCKIES  
AND THE NORTHERN PLAINS BEFORE LIFTING UP THROUGH SASKATCHEWAN AND  
MANITOBA. THE TIMING DIFFERENCES ASSOCIATED WITH THE COLD FRONT  
EJECTING OUT ACROSS THE PLANS ARE RATHER MODEST AT THIS TIME AT  
LEAST THROUGH WED. SINCE THE GFS APPEARS TO BE STILL A BIT MORE  
OUT OF TOLERANCE THROUGH THIS PERIOD COMPARED TO THE OTHER MODELS  
WHICH ARE BETTER CLUSTERED...IT HAS BEEN DECIDED TO LEAN TOWARD A  
NON-GFS CONSENSUS AT THIS TIME.  
 
   
..NEW CLOSED LOW/ENERGY REACHING THE PACIFIC NORTHWEST BY WED
 
   
..SURFACE LOW ADVANCING INTO WESTERN WA TUES NIGHT/WED
 
   
..DEEP TROUGH/CLOSED LOW EVOLUTION OVER THE WEST BY THURS
 
   
..SURFACE WAVE DEVELOPMENT OVER THE PLAINS BY FRI
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC CONSENSUS  
CONFIDENCE: AVERAGE  
 
THE MODELS AGREE IN BRINGING ANOTHER SURGE OF STRONG HEIGHT FALLS  
INTO THE NORTHWEST BY WED AS A SURFACE LOW MOVES INTO WESTERN WA.  
THIS WILL LEAD TO A LARGER SCALE DEEP TROUGH AND CLOSED LOW OVER  
THE WEST BY THURS. BY FRI...THE HEIGHT FALLS WILL BE ENCROACHING  
ON THE HIGH PLAINS AND WILL ALLOW A WAVE OF LOW PRESSURE TO  
DEVELOP ALONG THE AFOREMENTIONED COLD FRONT THAT EJECTS OUT ACROSS  
THE CENTRAL/NORTHERN PLAINS WITH THE INITIAL SURGE OF SHORTWAVE  
ENERGY/TROUGHING. THERE IS BETTER AGREEMENT TONIGHT WITH THE DEPTH  
OF THE RENEWED TROUGH AND ITS PLACEMENT...AND ALL OF THE MODELS  
AGREE THAT THERE WILL BE A SOMEWHAT ELONGATED UPPER LOW OVER THE  
INTERMOUNTAIN WEST BY EARLY FRI. ALTHOUGH THE 00Z CMC DOES APPEAR  
TO BE A TAD TOO DEEP. MOST OF THE MASS FIELD DIFFERENCES ACTUALLY  
TEND TO BE MORE RELATED TO THE SURFACE FRONT BY THE END OF THE  
PERIOD AND PLACEMENT OF THE SURFACE WAVE OVER THE PLAINS. THE 00Z  
ECMWF IS SOMEWHAT SLOWER WITH THE FRONT AND FARTHER NORTH WITH THE  
LOW CENTER...WITH THE 00Z GFS FARTHER EAST WITH THE FRONT AND LOW  
CENTER. THE 00Z NAM AND 00Z UKMET SPLIT THE DIFFERENCE. THE 00Z  
CMC MEANWHILE IS GENERALLY THE MOST SUPPRESSED WITH THE FRONT AND  
IS WELL SOUTHWEST WITH ITS LOW CENTER COMPARED TO THE MODEL  
CONSENSUS. SINCE THE CMC APPEARS TO BE THE OVERALL OUTLIER...A  
NON-CMC CONSENSUS WILL BE PREFERRED FOR THE TIME BEING.  
 
   
..HURRICANE JOSE
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC CONSENSUS OVERALL IS CLOSEST TO THE NHC TRACK  
CONFIDENCE: REFERENCE NHC PRODUCTS  
 
EARLY IN THE PERIOD...THE LATEST (03Z) NHC TRACK OF HURRICANE JOSE  
IS CLOSE TO THE GLOBAL MODEL CONSENSUS...ALTHOUGH THE 12Z ECMWF IS  
A TAD LEFT OF THE NHC TRACK THROUGH THE FIRST 36 HOURS. AFTER 48  
HOURS...THE 12Z CMC BECOMES FASTER THAN THE NHC TRACK AND IS  
FARTHER TO THE NORTHEAST WITH JOSE. THE 00Z NAM IS ALSO A BIT  
NORTH OF THE NHC TRACK. A NON-CMC CONSENSUS BETTER REPRESENTS THE  
NHC TRACK IN THE LATTER PERIODS AS JOSE SLOWS DOWN AND BEGINS TO  
POSSIBLY INITIATE A CLOCKWISE LOOP WELL SOUTHEAST OF NEW ENGLAND  
BY 84 HOURS.  
 
   
..BROAD UPPER TROUGH OVER THE SOUTHEAST AND GULF COAST REGION
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS ALLOW FOR A BROAD AND WEAK UPPER TROUGH TO BE LEFT  
BEHIND OVER THE SOUTHEAST AND THE GULF COAST STATES IN THE WAKE OF  
HURRICANE JOSE TRACKING NORTH UP OFF THE EAST COAST. THE MODELS  
ARE IN GOOD AGREEMENT WITH THE BROADER DETAILS OF THE TROUGH...SO  
A GENERAL MODEL BLEND WILL BE PREFERRED.  
 
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