267  
FXUS10 KWNH 301834  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
134 PM EST TUE JAN 30 2018  
 
VALID JAN 30/1200 UTC THRU FEB 03/0000 UTC  
   
.SEE NOUS42 KWNO (ADMNFD) FOR UPPER AIR INGEST STATUS
 
 
12Z MODEL EVALUATION WITH FINAL PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
...DEPARTING LONGWAVE TROUGH AND SURFACE LOW FROM THE EASTERN U.S.  
THIS EVENING...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL COMPROMISE  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.  
 
...COLD FRONT MOVING THROUGH THE NORTHERN PLAINS TODAY, GREAT  
LAKES ON WEDNESDAY, AND LOWER MISSISSIPPI VALLEY TO THE  
MID-ATLANTIC THURSDAY NIGHT...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL COMPROMISE  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE DIFFERENCES WITH THE COLD FRONT ARE SOMEWHAT SUBTLE, AND  
RELATE TO THE TIMING AS THE BOUNDARY CROSSES THE GREAT LAKES  
REGION. THROUGH THURSDAY NIGHT AT LEAST, THE 12Z GFS APPEARS A  
LITTLE FAST, BUT THESE DIFFERENCES ARE MINOR AND WITHIN AN  
ACCEPTABLE RANGE. THEREFORE, A GENERAL MODEL COMPROMISE APPEARS  
REASONABLE FOR THIS SYSTEM.  
 
NO SIGNIFICANT CHANGES WERE NOTED WITH THE 12Z ECMWF/UKMET/CMC  
COMPARED TO THEIR PREVIOUS 00Z CYCLES.  
 
...SURFACE LOW DEVELOPMENT WITH IMPACTS TO THE NORTHEAST THURSDAY  
NIGHT INTO FRIDAY MORNING...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z ECMWF/UKMET BLEND  
CONFIDENCE: AVERAGE  
 
SIMILAR TO THE PREVIOUS SYSTEM, THE DIFFERENCES HERE ARE SOMEWHAT  
SUBTLE BUT ENSEMBLE SCATTER LOW PLOTS SHOW THE 12Z GFS TOWARD THE  
SOUTH SIDE OF THE AVAILABLE MEMBERS AND THE 12Z GFS IS ALSO ON THE  
SOUTH SIDE OF THE LATEST DETERMINISTIC MODELS AS WELL. THE 12Z NAM  
APPEARS STRONGER AND IS ON THE NORTHWESTERN EDGE OF THE LATEST  
ENSEMBLE SURFACE LOWS BY 12Z/02. THE 12Z ECMWF AND 12Z CMC SHOW  
SIMILARLY WITH THE 12Z UKMET SOUTH.  
 
THE ENSEMBLE MEANS ARE IN BETWEEN THE MORE NORTHERN ECMWF/CMC AND  
MORE SOUTHERN UKMET SOLUTIONS, WITH A BLEND OF THE 12Z ECMWF/UKMET  
APPEARING THE BEST FIT. THIS BLEND ALSO ALIGNS IN THE MIDDLE OF  
THE LATEST ENSEMBLE MEMBERS AND NEAR THE CENTER OF WHERE TRENDS IN  
THE ENSEMBLE DATA ARE POINTING.  
 
...WEAKENING MID-LEVEL SHORTWAVE APPROACHING THE NORTHWEST ON  
FRIDAY ALONG WITH PRECEDING ONSHORE FLOW...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z GFS / 12Z ECMWF BLEND  
CONFIDENCE: AVERAGE  
 
DIFFERENCES ARE SMALL UNTIL LATE FRIDAY WITH THE TIMING OF THE  
SHORTWAVE TROUGH. THE ENSEMBLE MEANS SUPPORT A BLEND OF THE 12Z  
GFS AND 12Z ECMWF WHILE THE 12Z NAM APPEARS FASTER AND 12Z  
UKMET/CMC ARE SOUTH OF THE MEANS.  
 
NO SIGNIFICANT CHANGES WERE NOTED WITH THE 12Z ECMWF/UKMET/CMC  
COMPARED TO THEIR PREVIOUS 00Z CYCLES.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
OTTO  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page