085  
FXUS10 KWNH 140457  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1256 AM EDT MON OCT 14 2019  
 
VALID OCT 14/0000 UTC THRU OCT 17/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z INITIAL MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
SOUTHERN CANADA LOW PRESSURE THROUGH TUESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE DEEP UPPER VORTEX AND SURFACE LOW OVER ONTARIO IS NOW MOVING  
TOWARDS THE NORTHEAST AND SHOULD REACH NORTHERN QUEBEC BY TUESDAY  
AFTERNOON. THE PRIMARY FRONT HAS STALLED OVER THE SOUTHEAST U.S.  
WHILST THE SECONDARY FRONT WILL TRACK EASTWARD ACROSS THE  
CENTRAL/NORTHERN APPALACHIANS ON MONDAY. A COUPLE IMPULSES RIDING  
ALONG THE FRONT WILL ENHANCE PRECIPITATION TOTALS. THE GLOBAL  
DETERMINISTIC MODEL GUIDANCE IS IN EXCELLENT AGREEMENT WITH THE  
SYNOPTIC FEATURES AND THEREFORE A GENERAL MODEL BLEND IS PREFERRED.  
 
SHORTWAVE TROUGH AND LOW ACROSS THE NORTH-CENTRAL U.S.  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 00Z WEDNESDAY, THEN  
ECMWF/CMC/EC MEAN  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
SHORTWAVE ENERGY ORIGINATING FROM THE PACIFIC NORTHWEST WILL CROSS  
THE NORTHERN ROCKIES AND THEN THE NORTHERN PLAINS BY MONDAY NIGHT.  
THE NORTHERN STREAM TROUGH WILL DEEPEN AND CLOSE OFF AS IT  
APPROACHES THE UPPER MIDWEST AND GREAT LAKES, BECOMING A LONGWAVE  
TROUGH OVER THE EASTERN U.S. WITH A NEGATIVE TILT BY WEDNESDAY  
NIGHT. THIS WILL SPAWN A SURFACE LOW OVER THE UPPER MIDWEST ON  
TUESDAY AND ALSO PHASE WITH THE SOUTHERN STREAM DISTURBANCE ACROSS  
THE SOUTHEAST. THE RESULT WILL LIKELY BE A NOR'EASTER NEAR THE  
NORTHEAST COAST BY WEDNESDAY NIGHT. THE MODELS ARE IN GOOD  
AGREEMENT THROUGH TUESDAY EVENING, AFTER WHICH THE 00Z UKMET  
BECOMES MORE AMPLIFIED ALOFT AND THE 00Z GFS BECOMES SLIGHTLY  
FASTER. THEREFORE A BLEND OF THE ECMWF/CMC/EC MEAN SHOULD WORK  
WELL AFTER 00Z WEDNESDAY.  
 
SOUTHERN TIER SHORTWAVE AND RESULTING SURFACE LOW  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NAM/GFS/ECMWF  
CONFIDENCE: AVERAGE  
 
TROUGHING MOVING THROUGH THE WESTERN US WILL EVENTUALLY PINCH OFF  
A SOUTHERN STREAM SHORTWAVE ACROSS SOUTHERN CALIFORNIA EARLY  
MONDAY. THE MODELS HAVE COME INTO SLIGHTLY BETTER AGREEMENT WITH  
THE AMPLITUDE AND AXIS ORIENTATION AS THE SHORTWAVE TRACKS ACROSS  
THE FOUR CORNERS REGION. BY TUESDAY MORNING THIS WILL SPUR THE  
DEVELOPMENT OF A SURFACE LOW ACROSS THE CENTRAL PLAINS THAT WILL  
EVENTUALLY REACH THE SOUTHEAST U.S. BY WEDNESDAY AND MERGE WITH  
THE NORTHERN STREAM SYSTEM BY EARLY THURSDAY. THE 00Z UKMET  
BEGINS TO DIFFER BY 00Z WEDNESDAY BY HOLDING THE SHORTWAVE BACK  
FARTHER TO THE WEST ACROSS THE SOUTHERN ROCKIES, AND THE CMC  
INDICATES STRONGER SURFACE TROUGHING OVER THE NORTHERN GULF OF  
MEXICO BY 12Z WEDNESDAY. THEREFORE A BLEND OF THE NAM/GFS/ECMWF  
SHOULD SUFFICE AS A GOOD STARTING POINT.  
 
PACIFIC NORTHWEST BY MIDWEEK  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: DETERMINISTIC MODEL BLEND  
CONFIDENCE: AVERAGE  
 
A STRONG STORM SYSTEM ORIGINATING FROM THE GULF OF ALASKA IS  
EXPECTED TO BEGIN APPROACHING THE PACIFIC NORTHWEST COAST BY LATE  
TUESDAY NIGHT AFTER A PERIOD OF RELATIVELY QUIET WEATHER EARLY IN  
THE WEEK. ALTHOUGH THE SURFACE COLD FRONT IS FORECAST TO PASS  
THROUGH THE REGION MID-WEEK, THE PARENT SURFACE LOW IS EXPECTED TO  
REMAIN WELL TO THE NORTH ACROSS WESTERN CANADA. THERE ARE ONLY  
MINOR MODEL DIFFERENCES WITH THE SYNOPTIC SCALE FEATURES AT THIS  
TIME, SO A BLEND OF THE DETERMINISTIC GUIDANCE SHOULD WORK WELL.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
HAMRICK  
 

 
 
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