528  
FXUS10 KWNH 180652  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
251 AM EDT WED MAR 18 2020  
 
VALID MAR 18/0000 UTC THRU MAR 21/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..DEEP UPPER TROUGH/CLOSED LOW IMPACTING THE WEST
 
   
..LOW PRESSURE TRAVERSING THE HIGH PLAINS/MIDWEST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GFS, 00Z CMC AND 00Z ECMWF  
CONFIDENCE: AVERAGE  
 
A DEEP AND ELONGATED UPPER TROUGH WITH MULTIPLE CLOSED LOW CENTERS  
WILL PIVOT WELL INLAND ACROSS THE INTERMOUNTAIN WEST BY WEDNESDAY  
WHICH AND SET THE STAGE FOR LEE-SIDE CYCLOGENESIS OVER THE CENTRAL  
HIGH PLAINS. IN PARTICULAR, THE CLOSED LOW CENTER CURRENTLY  
SITUATED NEAR THE BASE OF THE TROUGH WEST OF THE BAJA PENINSULA  
WILL QUICKLY EJECT NORTHEAST ACROSS THE SOUTHWEST ON WEDNESDAY AND  
ARRIVE OVER THE CENTRAL HIGH PLAINS BY EARLY THURSDAY AND BE THE  
DOMINANT PLAYER IN DEEPENING SURFACE LOW PRESSURE ACROSS THIS  
REGION WHICH SHOULD LIFT NORTHEAST TOWARD THE UPPER GREAT LAKES BY  
EARLY FRIDAY. THE 00Z NAM IS AGAIN SOMEWHAT STRONGER AND FASTER  
THAN THE GLOBAL MODEL GUIDANCE WITH THIS SYSTEM, AND SUGGESTS A  
LOW TRACK A TAD NORTHWEST OF THE GLOBAL MODEL GUIDANCE RELATING TO  
ITS TRACK ACROSS THE MIDWEST AND UPPER GREAT LAKES. THE 00Z UKMET  
AGAIN APPEARS TO BE TOO SLOW WITH ITS HEIGHT FALL PROGRESSION AT  
LEAST INITIALLY ACROSS THE PLAINS. WILL MAINTAIN A PREFERENCE  
TOWARD THE MORE STRONGLY CLUSTERED 00Z GFS, 00Z CMC AND 00Z ECMWF  
SOLUTIONS.  
 
   
..CLOSED LOW/ENERGY LINGERING OVER THE GREAT BASIN FRIDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE LATEST GOES-17 AIRMASS RGB AND AMV DATA SHOW A WELL-DEFINED  
AND SOMEWHAT ELONGATED CLOSED LOW OVER WESTERN NV WHICH IS  
EMBEDDED IN THE AFOREMENTIONED DEEP WESTERN U.S. TROUGH AXIS. THIS  
PARTICULAR LOW CENTER DOES NOT EJECT EAST OVER THE NEXT FEW DAYS  
AND INSTEAD GETS LEFT BEHIND OVER THE GREAT BASIN. THE 00Z NAM  
TENDS TO PLACE THE SYSTEM A TAD EAST OF THE GLOBAL MODELS. ALL OF  
THE MODELS WEAKEN THE SYSTEM BY FRIDAY, AND SUGGEST THE ENERGY  
WILL ELONGATE MORE EAST/WEST AND SHEAR OUT ON SATURDAY. A NON-NAM  
BLEND WILL BE PREFERRED WITH THIS ENERGY.  
 
   
..SERIES OF TROUGHS ARRIVING OVER THE NORTHERN HIGH PLAINS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE MODELS BRING A SERIES OF NORTHERN STREAM SHORTWAVE TROUGHS  
DOWN TOWARD THE NORTHERN HIGH PLAINS, WITH ONE ARRIVING BY LATE  
WEDNESDAY, AND THEN AN ADDITIONAL ONE ON FRIDAY. THE 00Z NAM  
OVERALL IS A TAD SLOWER AND DEEPER THAN THE GLOBAL MODELS WITH THE  
INITIAL SYSTEM, AND THEN THIS MODEL ALONG WITH THE 00Z CMC TEND TO  
BE A LITTLE SLOWER AND DEEPER WITH THE SECOND ONE. HOWEVER, THE  
00Z UKMET APPEARS TO BE TOO PROGRESSIVE WITH ITS SECOND SHORTWAVE  
EVOLUTION. WILL PREFER THE CLUSTERING OF THE 00Z GFS AND 00Z ECMWF  
WITH THESE SHORTWAVES AS THEY ARRIVE ACROSS THE NORTHERN PLAINS  
AND ADVANCE EAST TOWARD THE UPPER MIDWEST AND GREAT LAKES REGION.  
 
   
..TROUGH ARRIVING OVER SOUTHERN CA BY SATURDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND  
CONFIDENCE: AVERAGE  
 
A NEW SURGE OF HEIGHT FALLS WILL BE DROPPING DOWN OFF THE WEST  
COAST BY THE END OF THE WEEK AS A DEEP CLOSED LOW CENTER EVOLVES  
SOUTH FROM THE GULF OF AK. AHEAD OF THIS CLOSED LOW WILL BE A  
SEPARATE AND SMALLER CLOSED LOW CENTER THAT GETS CAUGHT UP IN THE  
THE LARGER SCALE CYCLONIC FLOW OFF THE WEST COAST AND GETS  
SLINGSHOTTED EAST TOWARD SOUTHERN CA AS A PROGRESSIVE SHORTWAVE  
TROUGH. THE 00Z UKMET IS THE SLOWEST AND DEEPEST SOLUTION WITH  
THIS SYSTEM. WILL SUGGEST A NON-UKMET BLEND AT THIS POINT AS THE  
REMAINING GUIDANCE HAS COME INTO CLOSE AGREEMENT ON TIMING AND  
DEPTH.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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