260  
FXUS10 KWNH 091618  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1217 PM EDT WED OCT 09 2019  
 
VALID OCT 09/1200 UTC THRU OCT 13/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
09/12Z NAM/GFS EVALUATION WITH PREFERENCES  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..EAST COAST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: ANY OF THE OPERATIONAL MODELS  
 
A STACKED, CLOSED LOW FORMING THE LOWER PART OF A REX BLOCK WILL  
LINGER WITH RAIN OVER NEW ENGLAND BEFORE BEING PRODDED ALONG BY  
THE UPSTREAM CENTRAL U.S. CYCLONE. THE 12Z GFS TRENDED MORE IN  
LINE WITH THE OTHER OPERATIONAL MODELS, MAKING FOR A STRONG  
CONSENSUS AND THE ABILITY TO USE ANY OF THE OPERATIONAL MODELS FOR  
THIS SYSTEM THROUGH DAY 3.  
 
   
..CENTRAL U.S. MID-LATITUDE CYCLONE
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: ANY OF THE OPERATIONAL MODELS, DROPPING THE GFS AFTER  
12/00Z  
 
A VERY DEEP, 2 TO 3 STANDARD DEVIATION TROUGH, WILL SPIN UP INTO A  
LARGE SCALE CYCLONE WITH LOW PRESSURE TRACKING FROM COLORADO  
TOWARD NORTHERN MINNESOTA DURING THE MATURING PHASE, AND THEN  
LINGERING IN PLACE BENEATH A BUILDING SHORTWAVE RIDGE OVER CANADA.  
POTENTIALLY RECORD-BREAKING OCTOBER SNOWFALL IS POSSIBLE IN PARTS  
OF THE PLAINS, ALONG WITH STRONG WINDS. THE MODELS ARE IN VERY  
GOOD AGREEMENT WITH THIS LARGE SCALE STORM WITHIN THE UPPER AIR  
NETWORK. THE *BEST* CONSENSUS CLUSTERS AROUND THE ECMWF ENSEMBLE  
MEAN, AND SO WOULD INCLUDE MOST OF THE OPERATIONAL MODELS THROUGH  
DAY 3. THE EXCEPTION IS THE GFS WHICH TENDS TO CHANGE SHAPE ON DAY  
3, WITH ENERGY ROTATING AROUND AND DRAGGING THE MATURE CYCLONE  
TOWARD THE GREAT LAKES SOMEWHAT UNREALISTICALLY.  
 
   
..WEST COAST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF 12Z NAM / 00Z ECMWF  
 
A COMPLICATED MERGER OF TWO STREAMS AROUND 145 DEGREES WEST LEADS  
EVENTUALLY TO A MORE CONSOLIDATED OPEN TROUGH APPROACHING THE WEST  
COAST BY DAY 3. SOME SOLUTIONS SPLIT THE ENERGY AGAIN, WITH  
EMPHASIS ON A SOUTHERN STREAM TROUGH ANCHORED OFF CALIFORNIA, AND  
A LOW AMPLITUDE NORTHERN STREAM WAVE PUNCHING INTO THE NORTHWEST.  
WE PREFER SOLUTIONS THAT ARE CLOSER TO THE ECMWF MEAN, GIVEN ITS  
HANDLING OF THE NORTH AMERICAN PATTERN AS A WHOLE, AND BASED ON  
SYNOPTIC REASONING INVOLVING DIFFERENTIAL ADVECTION OVER THE  
PACIFIC. THE OPERATIONAL ECMWF MAY BE A BIT TOO SLOW AND  
CONSOLIDATED, AND THE NAM A BIT TOO FAST, BUT A BLEND OF THE TWO  
GETS CLOSE TO THE EC MEAN, AND IS A DECENT REPRESENTATION OF  
CONSENSUS.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
BURKE  
 

 
 
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