630  
FXUS10 KWNH 141637  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1236 PM EDT MON OCT 14 2019  
 
VALID OCT 14/1200 UTC THRU OCT 18/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z NAM/GFS MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
CLOSED MID LEVEL LOW AND SURFACE LOWS AFFECTING THE GREAT LAKES  
AND NORTHEAST TUE INTO THU  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON 12Z GFS BLEND  
CONFIDENCE: AVERAGE  
 
THE 12Z NAM IS CLOSE TO THE MODEL CONSENSUS WITH THE CLOSING MID  
LEVEL LOW OVER THE UPPER GREAT LAKES TUE. IT REMAINS CLOSE TO THE  
CONSENSUS AS IT TAKES ON A NEGATIVE TILT ACROSS NORTHERN NEW  
ENGLAND LATE WED INTO THU. WHILE IT IS CLOSE TO THE MODEL  
CONSENSUS WITH THE PRIMARY SURFACE LOW OVER SOUTHWEST QUEBEC WED  
AFTERNOON/EVENING, IT DEVELOPS A SECONDARY SURFACE LOW OFF THE  
SOUTHEAST COAST MUCH EARLIER THAN THE REMAINDER OF THE GUIDANCE,  
TRACKING IT INTO ME BY 18/00Z.  
 
THE 12Z GFS (AS WELL AS THE 06Z GEFS MEAN), HOWEVER, IS FASTER  
THAN THE CONSENSUS THROUGHOUT THE PROCESS, WITH THE SECONDARY  
SURFACE LOW TRACKING THROUGH NORTHERN NEW ENGLAND MUCH FASTER THAN  
THE CONSENSUS. BECAUSE OF THIS, THE 12Z GFS IS NOT INCLUDED IN THE  
PREFERRED BLEND, AS THE NON-NCEP GUIDANCE IS CLOSER TO THE 12Z NAM  
WITH THE EVOLUTION OF THE SECONDARY SURFACE LOW.  
 
SHORT WAVE ENERGY AFFECTING TEXAS WED/THU  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
 
SHORT WAVE ENERGY AT THE BASE OF THE DEVELOPING LONG WAVE TROUGH  
OFF THE WEST COAST EARLY WED TRACKS ACROSS THE SOUTHWEST STATES,  
REACHING CENTRAL TX BY 18/00Z. THERE IS SOME SPREAD WITH THIS  
SYSTEM AS IT REACHES TX, WITH THE 12Z GFS/06Z GEFS MEAN A BIT  
FASTER THAN THE 00Z ECMWF/00Z ECMWF ENSEMBLE MEAN. HOWEVER, THE  
SPREAD IS NOT SO GREAT AS TO ELIMINATE ANY ENSEMBLE OR  
DETERMINISTIC SOLUTION AT THIS TIME. THEREFORE, A GENERAL MODEL  
BLEND IS PREFERRED, BUT BECAUSE OF THE SPREAD, FORECAST CONFIDENCE  
WITH RESPECT TO THE PLACEMENT IS JUST AVERAGE.  
 
DEVELOPING LONG WAVE OVER THE WEST COAST WED/THU  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
 
BOTH THE 12Z NAM/GFS ARE IN LINE WITH THE MODEL CONSENSUS  
CONCERNING HOW THE STRONG CLOSED LOW SOUTH OF THE GULF OF ALASKA  
DROPS TO JUST WEST OF VANCOUVER ISLAND BEFORE 17/00Z. SHORT WAVE  
ENERGY DIVING SOUTH FROM THE CLOSED LOW AIDS IN CARVING OUT A LONG  
WAVE TROUGH NEAR THE WEST COAST BY 17/12Z, WHICH TRACKS INTO THE  
NORTHERN ROCKIES AND SOUTHWEST BY THE END OF THE PERIOD. WHILE  
THERE ARE SOME MINOR TIMING DIFFERENCES WITH RESPECT TO HOW  
QUICKLY THE LONG WAVE TROUGH DEVELOPS, THERE IS ENOUGH MODEL  
AGREEMENT TO SUPPORT A GENERAL MODEL BLEND FOR WED INTO THU.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
HAYES  
 

 
 
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