929  
FXUS10 KWNH 120457  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1156 PM EST MON NOV 11 2019  
 
VALID NOV 12/0000 UTC THRU NOV 15/1200 UTC  
 
..SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
...00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND  
CONFIDENCE...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..DEPARTING EAST COAST STORM SYSTEM TODAY/TONIGHT
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
NO SIGNIFICANT DIFFERENCES WERE NOTED WITH THIS SYSTEM UNTIL AFTER  
THE SURFACE LOW HAS EXITED NORTHWARD INTO THE CANADIAN MARITIMES.  
THE 12Z UKMET TRACKS THE SURFACE-850 MB LOW FARTHER INLAND THAN  
THE MODEL CONSENSUS, BUT GIVEN THIS DIFFERENCE HAS LITTLE TO NO  
IMPACT ON THE LOWER 48, A GENERAL MODEL BLEND IS PREFERRED.  
 
...SHORTWAVE TRACKING FROM THE NORTHWEST TO THE GREAT PLAINS FOR  
WEDNESDAY AND GREAT LAKES FOR THURSDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
GOOD AGREEMENT WAS NOTED IN THE DETERMINISTIC AND ENSEMBLE  
GUIDANCE REGARDING THIS SYSTEM. HOWEVER, THE 00Z GFS WAS SLIGHTLY  
SLOWER THAN THE REMAINING CONSENSUS, BUT THIS DIFFERENCE IS SMALL  
ENOUGH TO NOT BE A CONCERN WHEN USED AS PART OF A GENERAL MODEL  
BLEND.  
 
...WEAKENING CLOSED LOW CROSSING MEXICO AND POSSIBLE INTERACTION  
WITH SHORTWAVE DROPPING SOUTHWARD FROM THE LOWER MISSISSIPPI  
VALLEY ON FRIDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z ECMWF/UKMET BLEND  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
 
THE 00Z GFS IS SIGNIFICANTLY FASTER WITH THE CLOSED LOW CROSSING  
MEXICO INTO THE GULF OF MEXICO, ON THE FASTEST EDGE OF THE LATEST  
ENSEMBLE GUIDANCE. THE REMAINING DETERMINISTIC GUIDANCE IS IN GOOD  
AGREEMENT WITH THE REMNANT CLOSED LOW/SHORTWAVE CROSSING  
MEXICO/SOUTHERN TEXAS ON THURSDAY.  
 
LARGER DIFFERENCES EXIST WITH MID-LEVEL VORTICITY DROPPING  
SOUTHWARD (ORIGINATING FROM THE GULF OF ALASKA TUESDAY MORNING)  
INTO THE CENTRAL PLAINS AND EVENTUALLY THE LOWER MISSISSIPPI  
VALLEY THURSDAY NIGHT AS THE 00Z NAM AND 12Z CMC ARE FASTER  
STARTING THURSDAY MORNING. DIFFERENCES WITH THE 00Z GFS REGARDING  
THE SHORTWAVE TO THE SOUTH PRECLUDES ITS USABILITY ACROSS THE GULF  
COAST/LOWER MISSISSIPPI VALLEY.  
 
THE 12Z ECMWF/UKMET ARE IN FAIR AGREEMENT AND MATCH BEST TO THE  
AGREEABLE ENSEMBLE MEANS WITH THE 500 MB VORTICITY WITHIN THE  
TROUGH AXIS AND LOW LEVEL BAROCLINIC BOUNDARY IN THE GULF AND JUST  
OFFSHORE OF THE SOUTHEAST COAST. BLENDING THE 12Z ECMWF/UKMET  
SURFACE LOW POSITIONS ALONG THE FRONTAL BOUNDARY ARE BEST TO ALIGN  
WITH THE MIDDLE OF THE LATEST ENSEMBLE SCATTER LOW PLOTS.  
CONFIDENCE IS REDUCED GIVEN THE COMPLEXITY AND POTENTIAL  
INTERACTIONS OF VARIOUS FEATURES DOWNSTREAM AND UPSTREAM.  
 
...PAIR OF MID-LEVEL SHORTWAVES APPROACHING THE WEST COAST ON  
THURSDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
 
A RELATIVELY WEAK MID-LEVEL SHORTWAVE IS EXPECTED TO APPROACH THE  
OREGON/CALIFORNIA COASTLINES EARLY ON THURSDAY WHILE A SECOND  
SHORTWAVE LURKS TO THE NORTH WITH A LIKELY DESTINATION OF  
WASHINGTON/BRITISH COLUMBIA THURSDAY NIGHT. DESPITE SOME MINOR  
TIMING DIFFERENCES OF THESE TWO FEATURES, AGREEMENT IS GOOD ENOUGH  
TO WARRANT A GENERAL MODEL COMPROMISE WHICH ALIGNS WITH THE LATEST  
ENSEMBLE MEANS.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
OTTO  
 

 
 
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