580  
FXUS10 KWNH 161909  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
308 PM EDT MON MAR 16 2020  
 
VALID MAR 16/1200 UTC THRU MAR 20/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..DEEP UPPER TROUGH/CLOSED LOW IMPACTING THE WEST
 
   
..CYCLOGENESIS OVER THE CENTRAL HIGH PLAINS WEDNESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS  
NON-NAM AND NON-CMC BLEND...AFTER 60 HOURS  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
19Z UPDATE: NO SIGNIFICANT CHANGES TO THE EARLIER PREFERENCE WITH  
THE LATEST 12Z GUIDANCE NOW AVAILABLE.  
 
A DEEP UPPER TROUGH AND EMBEDDED CLOSED LOW ALONG THE WEST COAST  
WILL CONTINUE TO SETTLE SOUTH OVER THE NEXT COUPLE OF DAYS, AND  
THEN BEGIN TO PIVOT INLAND INTO THE INTERMOUNTAIN WEST BY  
WEDNESDAY WHICH WILL FOSTER LEE-SIDE CYCLOGENESIS OVER THE CENTRAL  
HIGH PLAINS. THE GUIDANCE IS IN GOOD AGREEMENT THROUGH ABOUT 60  
HOURS, BUT THEREAFTER A FEW OF THE MODELS DIVERGE ON THE EJECTION  
OF THE MID-LEVEL ENERGY AND SUBSEQUENT SURFACE LOW DEVELOPMENT  
ACROSS THE CENTRAL PLAINS. THE 12Z NAM ALONG WITH THE 00Z CMC ARE  
AHEAD OF THE REST OF THE DETERMINISTIC MODELS AND ENSEMBLE MEANS,  
AND ALSO THEREFORE HAVE A STRONGER/DEEPER SURFACE LOW THAT IS  
FURTHER TO THE NORTHEAST COMPARED TO THE GFS/ECMWF/UKMET  
SOLUTIONS. THE CONSENSUS FAVORS A SLOWER APPROACH AT THIS TIME AND  
THEREFORE, BEYOND 19.00Z (60 HOURS), A NON-NAM AND NON-CMC BLEND  
IS PREFERRED WHILE A GENERAL MODEL BLEND IS SUFFICIENT PRIOR TO  
THAT.  
 
   
..TROUGH ARRIVING OVER THE NORTHERN HIGH PLAINS WEDNESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-GFS BLEND  
CONFIDENCE: AVERAGE  
 
19Z UPDATE: WITH THE REST OF THE 12Z GUIDANCE AVAILABLE, THE GFS  
NOW APPEARS TO BE A BIT OF AN OUTLIER WITH THE PROGRESSION OF THE  
TROUGH OVER THE NORTHERN HIGH PLAINS. THE ECMWF/UKMET SLOWED DOWN  
SOMEWHAT, NOT TO THE DEGREE THAT THE NAM/CMC SUGGEST, BUT ENOUGH  
TO NOW FAVOR MORE OF A NON-GFS APPROACH AT LEAST FOR THE MASS  
FIELDS.  
 
POSITIVELY TILTED NORTHERN STREAM ENERGY IS EXPECTED TO SLIP DOWN  
INTO THE NORTHERN HIGH PLAINS BY MID-WEEK. AS NOTED BY THE  
PREVIOUS DISCUSSION, THE 12Z NAM CONTINUES TO BE SLOWER/DEEPER  
THAN THE REST OF THE GUIDANCE. THE 12Z GFS HAS SLOWED SOMEWHAT,  
AND IS A BIT BEHIND ITS 06Z GEFS MEAN, BUT ISN'T AS DEEP AS THE  
NAM. THE CMC MIRRORS THE NAM IDEA OF A SLOWER/DEEPER SOLUTION  
WHILE THE ECMWF IS STILL A WEAKER AND MORE PROGRESSIVE SOLUTION.  
ITS PHASING/INTERACTION WITH THE SOUTHERN STREAM ENERGY COMING OUT  
OF THE CENTRAL ROCKIES REMAINS UNCLEAR AND LIKELY WILL DICTATE HOW  
PROGRESSIVE THE EVENTUAL TROUGHING IS. FOR NOW, WILL NOT MAKE  
DRASTIC BLEND PREFERENCE CHANGES, AND CONTINUE TO FAVOR A  
GFS/ECMWF/UKMET BLEND. IF THE LATER 12Z ECMWF/UKMET TREND SLOWER,  
THAN MORE INCORPORATION OF THE NAM AND CMC WOULD BE PLAUSIBLE.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
TAYLOR  
 

 
 
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