630  
FXUS10 KWNH 041700  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION...CORRECTED  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1158 AM EST SUN FEB 04 2018  
 
VALID FEB 04/1200 UTC THRU FEB 08/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
   
..CORRECTED FOR CONTENT IN LAST SECTION
 
 
   
..12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
...SHORTWAVE TRACKING FROM THE UPPER MISSISSIPPI VALLEY INTO THE  
OHIO VALLEY TODAY...  
...SURFACE LOW TRACKING NORTHEAST FROM THE SOUTHEASTERN U.S.  
TODAY, STRENGTHENING ALONG THE NEW ENGLAND COAST THROUGH EARLY  
MONDAY MORNING...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS HAVE CONVERGED SINCE YESTERDAY TO A COMMON IDEA WITH  
ONLY MINOR DIFFERENCES NOTED IN THE LATEST GUIDANCE. A GENERAL  
MODEL BLEND IS PREFERRED TO SMOOTH OUT ANY REMAINING DIFFERENCES.  
 
...WEAK 700 MB SHORTWAVE TRACKING ACROSS THE CENTRAL PLAINS INTO  
THE MIDWEST ON MONDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-12Z NAM BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE 12Z NAM IS SLIGHTLY SHARPER/DEEPER/SLOWER WITH THE 700 MB  
SHORTWAVE AS IT REACHES THE MISSISSIPPI VALLEY NEAR 00Z/06. THE  
REMAINING DETERMINISTIC/ENSEMBLE CONSENSUS SUPPORTS A NON-12Z NAM  
BLEND FOR THIS SYSTEM.  
 
...MID-LEVEL SHORTWAVE CROSSING THE NORTHWEST TODAY, WITH  
ADDITIONAL ENERGY AMPLIFYING ACROSS THE FOUR CORNERS REGION  
TUESDAY EVENING AND INTO THE PLAINS ON WEDNESDAY...  
...NORTHERN STREAM SHORTWAVE CROSSING THE UPPER MISSISSIPPI VALLEY  
ON WED WITH  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z NAM / 12Z GFS / 00Z ECMWF BLEND  
CONFIDENCE: AVERAGE  
 
THE 00Z UKMET IS FASTER WITH THE NORTHERN AND SOUTHERN STREAM  
SHORTWAVES ASSOCIATED WITH THIS SYSTEM, NOTED AS EARLY AS TUESDAY  
MORNING. THE EFFECT IS FOR THE FRONT IN THE SOUTHERN PLAINS TO BE  
DISPLACED FARTHER SOUTH IN THE 00Z UKMET COMPARED TO THE REMAINING  
GUIDANCE. BY WEDNESDAY MORNING, THE 00Z CMC IS NOTED TO HAVE A  
MUCH STRONGER RIDGE CENTERED IN THE EASTERN PACIFIC. THE 12Z  
NAM/12Z GFS AND 00Z ECMWF ARE IN REASONABLE AGREEMENT AND ARE  
SUPPORTED BY THE LATEST ENSEMBLE MEANS. ENSEMBLE SPREAD IS MODEST  
AT THE SURFACE, BUT REASONABLE ALOFT.  
 
...SHORTWAVE APPROACHING THE PACIFIC NORTHWEST LATE WEDNESDAY  
NIGHT...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z ECMWF/UKMET BLEND  
CONFIDENCE: AVERAGE  
 
THE ENSEMBLE MEANS ARE IN GOOD AGREEMENT AND SHOW THE 00Z CMC IS  
TOO FAST WITH THE SHORTWAVE FORECAST TO NEAR THE PACIFIC NORTHWEST  
00Z/08. THE 00Z ECMWF/UKMET ARE CLOSEST TO THE ENSEMBLE MEANS  
WHILE THE 12Z NAM AND 12Z GFS ARE SLOWER. HOWEVER, ENSEMBLE  
SPAGHETTI HEIGHT SPREAD IS LARGE SO CONFIDENCE IN THIS PREFERENCE  
IS ONLY AVERAGE GIVEN THE 3 DAY TIME FRAME AND POTENTIAL FOR  
FUTURE CHANGES IN THE GUIDANCE. .  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
OTTO  
 

 
 
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