537   
FXUS10 KWNH 081901  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
301 PM EDT SUN MAR 08 2020  
  
VALID MAR 08/1200 UTC THRU MAR 12/0000 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF 12Z GFS, 12Z ECMWF, 00Z ECENS  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
  
---19Z UPDATE---  
NO CHANGE TO THE PRELIMINARY PREFERENCE. THE 12Z ECMWF IS FAIRLY  
CONSISTENT WITH ITS PRIOR RUN AND THE 12Z GFS. THE UKMET AND CMC  
REMAIN SLOWER FOR THE CLOSED LOW APPROACHING THE WEST COAST.  
  
---PREVIOUS DISCUSSION---  
THE MOST NOTEWORTHY TREND WITH THE ARRIVAL OF THE 12Z GFS AND NAM  
IS THAT THE GFS HAS SLOWED DOWN THE PROGRESSION OF THE CLOSED LOW  
APPROACHING THE WEST COAST. IT IS NOW MORE SIMILAR TO THE 00Z  
ECMWF AND ECMWF ENSEMBLE MEAN (AND THE PREVIOUS PREFERENCE). THE  
00Z UKMET AND 00Z CMC ARE SLOWER AND HAVE AN EXTENSION OF A  
LOW-MID LEVEL JET FURTHER INLAND OVER THE GREAT BASIN. THIS LEADS  
TO NOTABLE DIFFERENCES IN PRECIPITATION PATTERNS BY TUESDAY.  
MEANWHILE, THE 12Z NAM IS NOW FASTER THAN MOST OTHER GUIDANCE WITH  
THE CLOSED LOW. THE PREFERENCE IS TO LEAN TOWARD A BLEND OF THE  
12Z GFS AND 00Z ECMWF, WHICH IS MUCH CLOSER TO THE ENSEMBLE MEANS.  
  
THIS PREFERENCE APPLIES ELSEWHERE IN THE COUNTRY. WITH MODEL  
DIFFERENCES ARE NOT QUITE AS DRASTIC FOR OTHER SYSTEMS AND  
REGIONS, A BLEND OF THE 12Z GFS, 00Z ECMWF AND 00Z ECMWF ENSEMBLE  
MEAN SHOULD BE RELATIVELY SIMILAR TO A GENERAL MODEL BLEND.  
  
RAINFALL PLACEMENT IN THE OZARKS REGION ON DAY 3 IS THE SUBJECT OF  
SOME DISAGREEMENT, BUT THERE IS GREATER UNCERTAINTY AS THIS SEEMS  
TO BE RELATED TO CONVECTIVE PROCESSES ON THE NORTHERN PERIPHERY OF  
A POOL OF INSTABILITY. THEREFORE, CONVECTIVE MODE SHOULD PLAY A  
LARGER ROLE IN THE EVENTUAL CHARACTER OF THE QPF SWATH ACROSS THE  
REGION. FOR NOW, THE 00Z ECMWF AND 00Z ECMWF ENSEMBLE MEAN SEEM TO  
OFFER A REASONABLE PLACEMENT CLOSE TO THE NORTHERN INSTABILITY  
GRADIENT ON MOST MODELS.  
  
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
LAMERS  
  
  
 
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