148  
FXUS10 KWNH 281705  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1204 PM EST THU NOV 28 2019  
 
VALID NOV 28/1200 UTC THRU DEC 02/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND FORECAST  
CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
   
..DEEP CLOSED LOW CROSSING THE INTERMOUNTAIN WEST/PLAINS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z NAM AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE 12Z GFS HAS BEEN TRENDED TOWARD THE PREFERRED MODEL CONSENSUS,  
BUT IT REMAINS STRONGER AND INITIALLY A BIT FARTHER WEST WITH ITS  
LOW LEVEL LOW THAT FORMS IN THE CENTRAL HIGH PLAINS FRIDAY NIGHT.  
THE RESULT IS FOR SIGNIFICANTLY WARMER AIR FROM THE GFS IN THE LOW  
LEVELS TO BE DRAWN NORTHWARD INTO THE NORTH-CENTRAL U.S. FRIDAY  
NIGHT THROUGH SATURDAY. THE ECMWF MEAN AS WELL AS THE ECMWF HAVE  
BEEN FAIRLY CONSISTENT WITH SURFACE AND 850 MB LOW POSITIONS OVER  
THEIR PAST 4 12/00Z CYCLES. THE STRENGTH OF THE 12Z NAM COULD BE A  
BIT WEAK BUT WHEN BLENDED WITH THE STRONGER 00Z ECMWF, A FAVORABLE  
BLEND IS REACHED. THIS BLEND APPLIES TO POSITION AS WELL WITH THE  
00Z ECMWF'S SURFACE LOW A BIT TOWARD THE NORTH SIDE OF THE LATEST  
MODEL SPREAD. THE 00Z UKMET APPEARS TOO WEAK WHILE THE 00Z CMC  
POSITION IS OFF FROM THE PREFERRED CONSENSUS. THIS BLEND APPLIES  
THROUGH SUNDAY EVENING AS THE STORM SYSTEM NEARS THE EAST COAST  
WITH SECONDARY LOW DEVELOPMENT ALONG THE NORTHERN MID-ATLANTIC  
COAST.  
 
   
..UPPER LOW APPROACHING THE WEST COAST BY SUNDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF  
CONFIDENCE: AVERAGE  
 
BY SUNDAY, A NEW CLOSED LOW WILL BE EVOLVING OFFSHORE OF THE WEST  
COAST ALONG WITH LOW PRESSURE AT THE SURFACE. THE 00Z CMC AND 00Z  
UKMET BOTH APPEAR TO BE A TAD TOO WEAK WITH THIS SYSTEM AS WELL AS  
DISPLACED FROM THE FAVORABLE ENSEMBLE MEAN POSITIONS. THE 12Z NAM  
APPEARS TO BE DISPLACED TOO FAR WEST ON SUNDAY WITH THE 00Z ECMWF  
CLOSER TO THE COAST. THE 12Z GFS SPLITS THE DIFFERENCE BUT LIES  
CLOSER TO THE NAM POSITION. THE GEFS AND ECMWF MEANS SUPPORT A  
MIDDLE GROUND, BETWEEN THE 12Z GFS AND 00Z ECMWF CONCERNING THE  
500 MB LOW. REGARDING COLD FRONTAL TIMING, THE 12Z NAM IS SLOWEST  
WITH THE 00Z ECMWF TOWARD THE FASTER SIDE. A BLEND OF THE 00Z  
ECMWF WITH THE SLIGHTLY SLOWER 12Z GFS IS PREFERRED OVER THE  
SLOWER 12Z NAM GIVEN DIFFERENCES IN POSITION IN THE 700-500 MB  
LOW.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
OTTO  
 

 
 
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