514   
FXUS10 KWNH 311646  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1245 PM EDT TUE MAR 31 2020  
  
VALID MAR 31/1200 UTC THRU APR 4/0000 UTC  
  
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
SOUTHEAST U.S. SURFACE LOW AND SHORTWAVE TROUGH  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM COMPROMISE  
CONFIDENCE: HIGH  
  
THE SURFACE LOW CURRENTLY TRACKING EASTWARD ACROSS THE SOUTHEAST  
WILL EMERGE OVER THE WESTERN ATLANTIC TUESDAY NIGHT AND TRACK OUT  
TO SEA AND NORTH OF BERMUDA.  DIFFERENCES ARE RELATIVELY MINOR  
WITH THIS SYSTEM FOR THE MOST PART.  HOWEVER, THE 12Z NAM WAS THE  
FARTHEST NORTHWEST WITH THE SURFACE LOW WHICH TRACKS ACROSS THE  
WESTERN ATLANTIC AND MORE AMPLIFIED ALOFT COMPARED TO THE OTHER  
MODELS.  THE PREFERENCES IS TOWARD A NON-NAM CONSENSUS TO ACCOUNT  
FOR THE GOOD AGREEMENT OF THE OTHER MODELS.  
  
BROAD UPPER LEVEL GYRE OVER NORTHWEST WITH NORTHERN PLAINS  
SHORTWAVE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z GFS/00Z ECMWF/00Z UKMET BLEND  
CONFIDENCE: MODERATE  
  
AN UPPER LEVEL LOW OVER SOUTHWEST CANADA WILL REMAIN NEARLY  
ANCHORED IN PLACE FOR THE NEXT FEW DAYS, WITH A COUPLE OF  
SHORTWAVES PIVOTING AROUND IT.  THE FIRST SHORTWAVE PERTURBATION  
WILL PIVOT NORTHEASTWARD ACROSS MONTANA AND NORTH DAKOTA ON  
WEDNESDAY, SUSTAINING A SURFACE LOW ACROSS THE DAKOTAS.  THE MAIN  
MODEL DIFFERENCE HERE IS WITH THE 12 NAM, INDICATING A MUCH MORE  
AMPLIFIED SOLUTION BY 00Z THURSDAY, AND THE 00Z CMC A TAD SLOWER  
WITH THE TRAILING COLD FRONT.   
  
SHORTWAVE TRACKING ACROSS INTERMOUNTAIN WEST BY END OF THE WEEK  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z UKMET/ECMWF BLEND  
CONFIDENCE: LOW-MODERATE  
  
THE SECOND SIGNIFICANT SHORTWAVE PIVOTING AROUND THE UPPER LEVEL  
GYRE WILL CROSS THE PACIFIC NORTHWEST ON WEDNESDAY AND THEN REACH  
THE ROCKIES BY WEDNESDAY NIGHT.  THIS WILL SUPPORT LEE SURFACE  
CYCLOGENESIS OVER THE WESTERN HIGH PLAINS BY THURSDAY ALONG AN  
EXISTING FRONTAL BOUNDARY.  SIMILAR TO THE LEAD SHORTWAVE, THE NAM  
APPEARS STRONGER WITH THIS FEATURE CROSSING THE INTERMOUNTAIN WEST  
AND THE CMC A LITTLE BROADER WITH THE TROUGH AXIS.  THE 12Z GFS IS  
A LITTLE QUICKER IN BRINGING MID-LEVEL HEIGHT FALLS TO THE HIGH  
PLAINS.   
  
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
HAMRICK  
  
  
 
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