080  
FXUS10 KWNH 051638  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1136 AM EST MON FEB 05 2018  
 
VALID FEB 05/1200 UTC THROUGH FEB 09/0000 UTC  
 
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
INITIALIZATION ERRORS IN THE NAM/GFS DO NOT SEEM TO DEGRADE THEIR  
SHORT RANGE FORECASTS.  
 
UPPER TROUGH WEAKENING AS IT MOVES OUT OF THE SOUTHWEST  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM COMPROMISE; CONFIDENCE ABOVE AVERAGE  
 
THE 12Z NAM IS A LITTLE MORE AMPLIFIED ALOFT WITH THE UPPER TROUGH  
IN THE SOUTHWEST WHICH ALLOWS IT TO DRAG EASTWARD INTO TEXAS AS A  
STRONGER FEATURE ON WEDNESDAY. OVERALL, A BROAD TROUGH EXISTS  
OVER NORTH AMERICAN WITH A STRONG MID-LEVEL REFLECTION OF THE  
POLAR VORTEX ACROSS NORTHWEST QUEBEC. THIS SHOULD FORCE THE  
SYSTEM TO EJECT OUT RELATIVELY FLAT, ELIMINATING THE NAM FROM  
CONSIDERATION. THIS IS IMPORTANT IN THE MODEL INSTABILITY FIELDS  
ACROSS TX AS WELL AS QPF PATTERN ACROSS THE SOUTHERN PLAINS, LOWER  
MS VALLEY, AND MID-SOUTH. SEE THE QPF DISCUSSION FOR MORE DETAILS  
ON THE PRECIPITATION FORECAST.  
 
SHORTWAVE MOVING TOWARDS THE NORTHWEST THURSDAY  
SHORTWAVE MOVING ACROSS NEW ENGLAND TUESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
THE GUIDANCE IS WITHIN REASON WITH THESE SYSTEMS. A COMPROMISE OF  
THE 00Z CANADIAN, 00Z ECMWF, 00Z UKMET, 12Z NAM, AND 12Z GFS  
SHOULD WORK OUT WELL WITH ABOVE AVERAGE CONFIDENCE.  
 
ROTH  
 
PREVIOUS MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
PREVIOUS 500 MB FORECASTS AT  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  

 
 
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