014  
FXUS10 KWNH 150434  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1234 AM EDT WED APR 15 2020  
 
VALID APR 15/0000 UTC THRU APR 18/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..SHORTWAVE ENERGY MOVING ACROSS MIDWEST/OHIO VALLEY DAY 2/3  
 
---------------------  
MODEL BLEND PREFERENCE: 12Z ECMWF, ECENS MEAN, AND UKMET  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
SHORTWAVE ENERGY MOVING THROUGH THE INTER-MOUNTAIN WEST IS  
EXPECTED TO SHEAR TO THE EAST ACROSS PORTIONS OF THE MIDWEST/OHIO  
VALLEY FRIDAY AS IT BECOMES ABSORBED INTO THE WESTERLY MEAN FLOW.  
AS THIS HAPPENS AND INFLUENCE FROM NORTHERN STREAM ENEGY OVER THE  
GREAT LAKES, A WEAK SURFACE LOW IS FORECAST TO DEVELOP AND MOVE  
THROUGH THE OHIO VALLEY. THE GFS AND NAM ARE TOO PROGRESSIVE/NORTH  
AND STRONG WITH THE SHORTWAVE ENERGY AND THEREFORE HAVE A MUCH  
DEEPER LOW AT THE SURFACE. THE ECMWF/UKMET AND ECENS MEAN HAS BEEN  
CONSISTENTLY A MORE FAVORABLE SOLUTION AND REMAINS THE PREFERRED  
BLEND FOR MASS FIELDS AND QPF FOR THIS TIME FRAME.  
 
WESTERN/CENTRAL CONUS  
--------------------  
MODEL BLEND PREFERENCE: GENERAL MODEL BLEND DAY 1/2, 12Z  
ECMWF/UKMET/ECENS MEAN BLEND DAY 3  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
ANOMALOUS UPPER LEVEL RIDGE OVER THE EASTERN PACIFIC BEGINS TO  
BREAK DOWN AS A SHORTWAVE TROUGH UNDERCUTS ITS AND THEN CLOSES  
OFFSHORE THE WESTERN U.S. COAST. THROUGH 48 HOURS, THERE IS VERY  
GOOD AGREEMENT WITH THE DEPTH AND PROGRESSION OF THIS FEATURE AND  
EVEN INTO DAY 3 AS THE SYSTEM OPENS UP OVER THE SOUTHWEST, THERE  
IS FAIRLY GOOD AGREEMENT. THE UKMET IS A BIT FASTER THAN THE REST  
OF THE GUIDANCE AND NOW THE GFS IS ON THE SLOWER SIDE BUT FOR THE  
MOST PART, A GENERAL MODEL BLEND FOR THIS FEATURE IS PREFERRED.  
 
SHORTWAVE ENERGY WILL ALSO MOVE THROUGH THE NORTHERN ROCKIES AND  
THEN ACROSS THE INTER-MOUNTAIN WEST IN THE DAY 1/2 TIME FRAME. THE  
00Z GFS/NAM QUICKLY BECOME UNUSABLE AFTER ABOUT 36 HOURS AS THE  
SHORTWAVE IS TOO STRONG AND TOO FAST COMPARED TO THE REST OF THE  
GUIDANCE AND THE ENSEMBLE MEANS. ESPECIALLY BY DAY 3 /FRIDAY/ THE  
GFS BEGINS TO SHEAR THE SHORTWAVE TOO STRONGLY TO THE EAST,  
STRINGING OUT THE VORTICITY LOBE FASTER THAN THE REMAINING  
GUIDANCE. FOR THESE REASONS A ECMWF/ECENS MEAN/UKMET IS PREFERRED  
FOR MOST OF THE WEST D3 AS THEY ARE CONSISTENT AND MATCH WELL TO  
EACH OTHER.  
 
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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