870  
FXUS10 KWNH 210445  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1244 AM EDT MON OCT 21 2019  
 
VALID OCT 21/0000 UTC THRU OCT 24/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
DEEPENING CENTRAL PLAINS CYCLONE; SECONDARY LOW FROM CAROLINAS TO  
NEW ENGLAND TUE-WED.  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
ALOFT, MODEL SPREAD HAS LESSENED AND THERE IS FAIRLY TIGHT  
CLUSTERING WITH THE LATEST MASS FIELDS WITH THE MID/UPPER LEVEL  
CLOSED LOW CURRENTLY OVER THE CENTRAL PLAINS. OVER THE NEXT COUPLE  
OF DAYS IT WILL LIFT THROUGH THE UPPER MIDWEST AND INTO PORTIONS F  
WESTERN ONTARIO. AT THE SURFACE, THE LOW SHOULD GENERALLY MAINTAIN  
ITS STRENGTH OR DROP ABOUT ANOTHER ~10 MB OVER SOUTHERN MINNESOTA,  
AFTER WHICH THE SYSTEM BECOMES STACKED AND GRADUALLY FILLS AS IT  
MOVES INTO WESTERN ONTARIO AFTER 60 HOURS. A SECONDARY AREA OF LOW  
PRESSURE WILL DEVELOP ACROSS THE CAROLINAS TUESDAY EVENING AND  
LIFT NORTHEAST ALONG THE EASTERN U.S. COAST. AGAIN HERE THE MODEL  
SPREAD IS FAIRLY LIMITED AND THERE DECENT AGREEMENT WITH THE 00Z  
GFS/NAM WITH THE EARLIER 12Z GUIDANCE. A GENERAL MODEL BLEND IS  
PREFERRED GIVEN THE AVERAGE TO ABOVE AVERAGE MODEL AGREEMENT AND  
FORECAST CONFIDENCE.  
 
STRONGER SHORTWAVE DROPPING THROUGH ROCKIES EARLY TO MID WEEK  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z GFS WITH 12Z ECENS/GEFS MEANS  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
 
A STRONGER, COMPACT SHORTWAVE TROUGH WILL DROP THROUGH THE  
CANADIAN ROCKIES AND INTO THE PLAINS MID-WEEK AND WITH BUILDING  
HEIGHTS OVER THE EASTERN/NORTHEAST PACIFIC, A MORE AMPLIFIED UPPER  
LEVEL PATTERN IS EXPECTED TO EVOLVE OVER THE WESTERN/CENTRAL  
CONUS. THE FAST MOVING CLIPPER-LIKE LOW HAS DECENT AGREEMENT WITH  
PRIMARILY SPEED DIFFERENCES NOTED BETWEEN THE FASTER/STRONGER  
UKMET AND NAM. THE GFS AND ECMWF ARE A BIT SLOWER AND WEAKER,  
ESPECIALLY AS THE LOW REACHES THE UPPER MIDWEST. AT 500 MB, THE  
ECMWF DIGS THE TROUGH FURTHER SOUTH INTO THE FOUR CORNERS REGION  
THAT ANY OF THE OTHER DETERMINISTIC MODELS (THE UKMET IS CLOSE)  
AND THIS IS OUTSIDE THE ENSEMBLE MEAN SPREAD A BIT. WITH THIS IN  
MIND, WILL FAVOR THE ECENS/GEFS MEANS ALONG WITH THE 00Z GFS.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
TAYLOR  
 
 
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