245  
FXUS10 KWNH 200642  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
142 AM EST MON NOV 20 2017  
 
VALID NOV 20/0000 UTC THRU NOV 23/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL PREFERENCES WITH CONFIDENCE INTERVALS  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT  
RANGE FORECASTS.  
 
STRENGTHENING UPPER TROUGH OVER THE GULF OF MEXICO  
BAROCLINIC LOW IN THE SOUTHEAST GULF WED/THU  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-ECMWF BLEND; CONFIDENCE SLIGHTLY ABOVE AVE  
 
DESPITE GOOD AGREEMENT UPSTREAM ACROSS THE PLAINS AND WEST, ISSUES  
ALOFT REMAIN IN THIS REGION WHICH LEAD TO A BIT OF SPREAD AT THE  
SURFACE. THE 00Z ECMWF WAS THE SHARPEST (THOUGH WEAKEST WITH THE  
500 HPA HEIGHT FIELD) ALOFT, WHICH LED TO THE MOST SOUTHWESTERLY  
SURFACE LOW. THE 00Z GFS HAD THE STRONGEST BUNDLE OF ENERGY ALOFT  
THE FARTHEST NORTH. THE AMPLIFYING FLOW PATTERN SUGGESTS LOWER  
MID-LEVEL HEIGHTS THAN THE ECMWF ADVERTISES AND A FARTHER SOUTH  
MID-LEVEL BUNDLE OF ENERGY THAN SEEN IN THE 00Z GFS. A COMPROMISE  
OF THE 00Z GFS, 00Z NAM, 00Z UKMET, AND 00Z CANADIAN APPEARS BEST  
HERE, WHICH IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.  
 
NORTHEAST WEDNESDAY INTO THURSDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: MODEL BLEND; SLIGHTLY ABOVE AVE CONFIDENCE  
 
WHILE THE 12Z ECMWF AND 00Z GFS SHOW UNUSUAL CONVECTIVE FEEDBACK  
WITH A SURFACE LOW THEY TAKE INTO ATLANTIC CANADA, THEIR SOLUTIONS  
DO NOT APPEAR TO CONTORT THE RAINFALL PATTERNS TOO STRONGLY ACROSS  
THE NORTHEAST. A COMPROMISE OF THE 00Z NAM, 00Z GFS, 00Z  
CANADIAN, 00Z UKMET, AND 00Z ECMWF IS PREFERRED WITH SLIGHTLY  
ABOVE AVERAGE CONFIDENCE.  
 
WARM FRONT LIFTING NORTH NEAR THE NORTHWEST TUESDAY  
DEEP LAYER CYCLONE OFFSHORE SOUTHWEST CANADA/THE NORTHWEST  
LOW MOVING INTO THE NORTHERN PLAINS/MIDWEST WED/THU  
SURFACE LOW MOVING BY THE CENTRAL US/CAN BORDER MON & TUE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE SYSTEMS. A  
COMPROMISE OF THE 00Z NAM, 00Z GFS, 00Z CANADIAN, 00Z UKMET, AND  
00Z ECMWF IS ADVISED WITH ABOVE AVERAGE CONFIDENCE.  
 
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ROTH  

 
 
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