570  
FXUS10 KWNH 161619  
PMDHMD  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1119 AM EST THU NOV 16 2017  
 
VALID NOV 16/1200 UTC THRU NOV 20/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL PREFERENCES WITH CONFIDENCE INTERVALS  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
SYSTEM LEAVING NEW ENGLAND TODAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE 00Z UKMET ONCE AGAIN LAGS THE OVERALL CONSENSUS AS THE  
SURFACE/STACKED LOW LIFTS INTO SE CANADA FRI. OTHERWISE...THERE  
REMAIN SOME LINGERING DEPTH DISCONTINUITIES (2-3 MB AT THE  
SURFACE) THE PLACEMENT/SHAPE LOOK STRONG ENOUGH TO SUPPORT A  
NON-UKMET BLEND AT ABOVE AVERAGE CONFIDENCE.  
 
NORTHERN STREAM S/W AND CYCLONE LIFTING ACROSS SOUTHERN CANADA  
WITH COLD FRONT MOVING THROUGH NORTHERN TIER TODAY TO SAT MORNING  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE LEAD SHORTWAVE/HEIGHT FALLS FROM THE MAIN UPPER LOW ALONG THE  
WEST COAST IS CURRENTLY CROSSING INTO THE US/CANADIAN BORDER  
ROCKIES OUT OF E WA...MODELS HAVE COME INTO A NEAR CONSENSUS WITH  
ITS FUTURE EVOLUTION INCLUDING THE LEE SURFACE CYCLONE. THIS WAVE  
WILL TRACK FROM S ALBERTA TODAY TO NE MANITOBA BY LATE FRIDAY  
BEFORE SHOWING ANY REAL DIFFERENCES/DEPARTURES. THIS INCLUDES  
THE TIMING OF THE FRONTAL ZONE CROSSING INTO THE GREAT LAKES AND  
CONNECTING BACK TO THE DEVELOPING CENTRAL PLAINS LOW. AS SUCH  
WILL SUPPORT A GENERAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE.  
 
CYCLONE MOVING FROM CENTRAL PLAINS TO GREAT LAKES TO NEW ENGLAND  
FRI...SAT...SUN WITH ATTENDANT FRONTAL ZONE THROUGH THE SOUTH  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC BLEND  
CONFIDENCE: AVERAGE  
 
OVERALL EVOLUTION OF THE BASE OF THE LARGE WESTERN TROF CONTINUES  
TO CONSOLIDATE BUT SMALL BUT IMPORTANT DIFFERENCES CONTINUE TO  
LEAD TO MODERATE SPREAD PARTICULARLY TOWARD THE PRECISE  
LOCATION/TRACK OF THE SURFACE WAVE AND THE TIMING OF THE ATTENDANT  
COLD FRONT ESPECIALLY ON SUN. THE 12Z NAM AND GFS BOTH SHIFTED  
SOUTH WITH THE TRACK WHILE BROADENING THE OVERALL WAVELENGTH OF  
THE TROF (BEGINNING TO BE ROUNDER AS IT LIFTS OUT OF THE OH/TN  
VALLEY INTO NEW ENGLAND. THIS IS OPPOSED BY A MORE ELONGATED  
EMERGENCE LIFTING NORTH BY THE ECWMF/CMC AND UKMET. THE 00Z CMC  
LOOKS MOST OF OF PLACE IS COMPARISON PLOTS BEING A BIT TOO FAST  
ESPECIALLY IN TIMING OF THE COLD FRONT THROUGH THE SOUTH AND AS  
SUCH WILL BE REMOVED FROM ANY PREFERENCE AT THIS TIME. A NON-CMC  
BLEND SHOULD SUFFICE AT THIS TIME BUT MODEST MASS SPREADS WITH THE  
LOW TRACK CONFIDENCE IS AVERAGE IN THIS BLEND.  
 
TROUGH AND SURFACE WAVE APPROACHING VANCOUVER ISLAND LATE SAT WITH  
FRONTAL ZONE SLIPPING INTO NW BY LATE SUN  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
BY FRIDAY A SHORTWAVE BEGINS TO AMPLIFY ACROSS THE GULF OF AK AND  
DRAW SOME SOUTHERN ENERGY INTO IT BROADENING THE TROF BY SAT AS IT  
SLOWLY DROPS TOWARD THE PACIFIC NORTHWEST. CORRALLED BY A SURFACE  
WAVE LIFTING NORTHEAST INTO CENTRAL BC BY 00Z SUN...THE MOISTURE  
TONGUE WILL BEGIN TO PULL NORTHWARD AS WELL AND BY SUNDAY WILL BE  
DIRECTED TOWARD VANCOUVER ISLAND. IT IS IN THE INTERACTION TIMING  
AND STRENGTH OF THE SOUTHERN WAVE THAT GENERALLY LEADS TO MODEST  
MODEL SPREAD TOWARD SAT/SUN AND HOW FAST/STRETCHED IT BECOMES AS  
IT PROGRESSES SOUTHEAST. THE BULK OF ENSEMBLE SOLUTIONS ARE  
TRENDING TO A SHARPER SOLUTION WITH MODEST POSITIVE TILT  
ORIENTATION. THE 00Z CMC IS A BIT MORE AGGRESSIVE/STRONG IN THE  
SOUTHERN PORTION OF THE TROF BY SUNDAY AND PRESSES THE BASE'S  
HEIGHT FALLS FORWARD FASTER. THE GFS WHICH HAD BEEN LAGGING  
SIGNIFICANTLY HAS TRANSITIONED FASTER TO BECOME MUCH CLOSER TO THE  
OTHERWISE AGREEABLE 12Z NAM AND 00Z ECMWF/UKMET REPRESENTING THE  
THE MIDDLE OF THE MODEST ENSEMBLE SPREAD. A SLIGHT EASTWARD SHIFT  
AT THE NORTHERN PORTION OF THE TROF BY 00Z MON WAS NOTED IN THE  
12Z NAM RUN RELATIVE TO THE GFS/UKMET/ECMWF BUT SEEMS MINOR IN FOR  
A DAY 3 TO KEEP IT WITHIN THE OVERALL PREFERENCE. AS SUCH A  
NON-CMC BLEND IS SUGGESTED WITH GREATEST WEIGHTING TOWARD THE  
ECWMF. CONFIDENCE IS SLIGHTLY ABOVE AVERAGE.  
 
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
GALLINA  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page