712  
FXUS10 KWNH 100717  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
216 AM EST WED JAN 10 2018  
 
VALID JAN 10/0000 UTC THRU JAN 13/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
   
..WINTER STORM WITH NEAR BLIZZARD CONDITIONS IN THE MIDWEST
 
   
..CYCLONE GRADUALLY DEVELOPING FROM THE SOUTHERN TO EASTERN U.S
 
 
PREFERENCE: 00Z NAM / 00Z UKMET / 00Z CANADIAN  
CONFIDENCE: BELOW AVERAGE  
 
A FULL LATITUDE TROUGH WITH EMBEDDED NORTHERN AND SOUTHERN STREAM  
COMPONENTS WILL MOVE EAST ACROSS THE COUNTRY. MODELS ARE IN  
AGREEMENT EARLY OVER THE MIDWEST/PLAINS THROUGH DAY 1...WITH  
MINIMAL SPREAD THROUGH DAY 2. BY DAY 3...HOWEVER...ENDING 12Z  
SATURDAY THE 13TH...MODEL BEHAVIOR FROM RUN TO RUN IS NOT  
INSPIRING MUCH CONFIDENCE AS TO THE DETAILS OF THE CYCLONE THAT  
EVOLVES OUT OF THE SOUTHERN PORTION OF THE TROUGH...TRACKING FROM  
THE SOUTHERN STATES TOWARD THE MID ATLANTIC / APPALACHIANS...AND  
AFFECTING THE GREAT LAKES AND NEW ENGLAND. THE 00Z GFS WAS THOUGHT  
TO BE TOO FAST...WITH A VERY FLAT SURFACE WAVE ALONG THE EAST  
COAST. THE 00Z ECMWF...HOWEVER...TRENDED EVEN FASTER THAN THE  
GFS...A DRAMATIC BREAK FROM ITS EARLIER FORECAST. STILL...THERE  
ARE A MAJORITY OF GEFS MEMBERS STILL IN FAVOR OF A SLOWER AND MORE  
ROBUST SOLUTION...SIMILAR TO THE 00Z NAM/UKMET/CANADIAN...AS WELL  
AS THE PRIOR 12Z ECMWF. GIVEN THE DEPTH AND SIZE OF THE UPPER  
TROUGH...IT WOULD BE SOMEWHAT SURPRISING TO SEE SUCH A RAPID  
SURFACE PROGRESSION AS THE 00Z GFS/ECMWF ARE DEPICTING.  
 
WPC WILL BE USING BLENDS THAT CENTER ON THE NAM/UKMET/CANADIAN AND  
PRIOR 12Z ECMWF...WITH HIGH CONFIDENCE AS TO WINTER WEATHER  
IMPACTS...BUT LOW CONFIDENCE AS TO THE DETAILS...A GOOD CASE FOR  
USING THE PROBABILISTIC GRIDS RATHER THAN DETERMINISTIC FOR LOCAL  
MESSAGING AND DECISION MAKING.  
 
BURKE  
 
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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