804  
FXUS10 KWNH 070646  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
145 AM EST TUE JAN 07 2020  
 
VALID JAN 07/0000 UTC THRU JAN 10/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..SOUTHERN STREAM TROUGH/LOW OVER THE TN VALLEY
 
   
..SURFACE LOW IMPACTING THE MID-ATLANTIC/NORTHEAST ON TUES
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
A COMPACT, PROGRESSIVE SHORTWAVE TROUGH CURRENTLY ADVANCING TOWARD  
THE TN VALLEY WILL BE GRADUALLY AMPLIFYING ON TUESDAY AS IT  
CROSSES THE MID-ATLANTIC REGION. THIS WILL ALLOW AN ATTENDANT WAVE  
OF LOW PRESSURE TO DEEPEN AS IT CROSSES FROM THE TN VALLEY TO THE  
LOWER CHESAPEAKE BAY/VA TIDEWATER REGION BY TUESDAY EVENING. THE  
SYSTEM WILL THEN QUICKLY EXIT OUT TO SEA SOUTHEAST OF NEW ENGLAND  
THROUGH EARLY WEDNESDAY. OVERALL, THE MODELS ARE IN VERY GOOD  
AGREEMENT WITH THE SYSTEM, WITH VERY MODEST DIFFERENCES WITH  
RESPECT TO TIMING/DEPTH, AND SO A GENERAL MODEL BLEND WILL BE  
PREFERRED.  
 
   
..NORTHERN STREAM TROUGH CROSSING THE NORTHEAST BY WED
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS ADVANCE A NORTHERN STREAM UPPER TROUGH AND ATTENDANT  
COLD FRONT ACROSS THE GREAT LAKES ON TUESDAY, AND THEN THROUGH THE  
NORTHEAST ON WEDNESDAY. VERY GOOD MODEL AGREEMENT IS SEEN WITH  
THIS ON THE LARGE SCALE, SO A GENERAL MODEL BLEND WILL BE  
PREFERRED WITH THIS ENERGY AS WELL.  
 
   
..PARADE OF SHORTWAVES CROSSING THE PACIFIC NORTHWEST
 
   
..ENERGY ADVANCING EAST ACROSS THE PLAINS/MIDWEST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
BY LATE TUESDAY AND INTO WEDNESDAY, THERE WILL BE ANOTHER  
SHORTWAVE TROUGH AND FRONT CROSSING THE COAST OF THE PACIFIC  
NORTHWEST. ON THE LARGE SCALE SENSE, THE TIMING/STRENGTH APPEARS  
VERY AGREEABLE BETWEEN THE VARIOUS DETERMINISTIC MODELS. AS THIS  
SYSTEM TRAVERSES THE INTERMOUNTAIN WEST AND THEN THE HIGH PLAINS  
BY EARLY THURSDAY, THERE WILL BE ANOTHER SHORTWAVE CROSSING THE  
PACIFIC NORTHWEST THAT WILL THEN DIVE SOUTHEAST TOWARD THE FOUR  
CORNERS REGION LATE THURSDAY AND FRIDAY. THERE IS A BIT MORE  
SPREAD SEEN IN THE GUIDANCE WITH THIS LATTER SYSTEM, AS THE 00Z  
NAM APPEARS A TAD TOO PROGRESSIVE. FARTHER NORTH, THE INITIAL  
SYSTEM WILL DRIVE CYCLOGENESIS OUT ACROSS THE NORTHERN PLAINS  
WHICH WILL CROSS THE UPPER MIDWEST AND GREAT LAKES. THE NAM  
APPEARS TO BE TOO FAR NORTH WITH ITS LOW TRACK, WITH THE 00Z ECMWF  
PERHAPS OCCASIONALLY A LITTLE TOO SLOW AND THE 00Z GFS A LITTLE  
TOO FAST. OVERALL, THE NAM IS GENERALLY THE SOLUTION THAT IS MORE  
OUT OF PHASE WITH THE MODEL CONSENSUS, SO A NON-NAM BLEND WILL BE  
PREFERRED WITH THE SUCCESSION OF SHORTWAVES ADVANCING THROUGH THE  
PACIFIC NORTHWEST AND EJECTING DOWNSTREAM TOWARD THE PLAINS AND  
MIDWEST, AND THIS SHOULD ADDRESS SOME OF THE MODEST TIMING  
DIFFERENCES NOTED.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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