MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 121 AM EDT TUE MAY 16 2017 VALID MAY 16/0000 UTC THRU MAY 19/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...SHORTWAVE LIFTING OUT OF CNTRL HIGH PLAINS EARLY THIS MORNING PHASING WITH LINGERING TROF ENERGY OVER S-CNTRL CANADA TUES...SHIFTING INTO ONTARIO BY WED WITH ASSOCIATED SURFACE WAVE... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/12Z ECMWF/12Z UKMET BLEND CONFIDENCE: AVERAGE TRENDS CONTINUE TO SHOW FASTER WITH THE SURFACE LOW FORECAST TO TRACK NEWD ACROSS MN LATER TODAY. THERE ARE ONLY MINOR PLACEMENT DIFFERENCES WITH THE SURFACE LOW AS IT TRACKS INTO S-CNTRL...AND THE LATEST ENSEMBLE SCATTER LOW PLOTS SHOW THE CMC LOWS CLUSTERED SEPARATELY FROM THE ECMWF LOWS WHICH ARE SEPARATE FROM THE GEFS LOWS TO THE NORTH BY 00Z/17. THE DETERMINISTIC RUNS ARE IN THE SAME GENERAL BALLPARK BUT THE 12Z CMC AND 00Z NAM ARE NORTH BY 00Z/17. THESE DIFFERENCES AMPLIFY INTO AND ACROSS CANADA BUT SENSIBLE WEATHER IMPACTS ACROSS THE U.S. AFTER WEDNESDAY ARE MINIMAL FROM THIS SYSTEM. ...CLOSED LOW OVER SOUTHWEST U.S. SHIFTING ACROSS NM LATE TUES EJECTING CONSOLIDATING AND LIFTING NORTH THROUGH CENTRAL PLAINS WED INTO UPPER MIDWEST THURS WITH ASSOCIATED SURFACE LOW... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 00Z NAM BLEND CONFIDENCE: AVERAGE THE 00Z NAM IS ON THE NORTH SIDE WITH THE CENTER OF THE SHORTWAVE AND HAS A MORE NEUTRAL TILT COMPARED TO THE REMAINING DETERMINISTIC GUIDANCE BY 12Z/17. THE NAM EVENTUALLY ACQUIRES A NEGATIVE TILT...JOINING SIMILAR TO THE REMAINING GUIDANCE BY 12Z/18 BUT BECOMES A BIT AHEAD WITH HEIGHT FALLS. THE 00Z NAM IS FASTER WITH THE SURFACE LOW TRACK INTO SERN CANADA AND DOES NOT FIT IN WITH THE LATEST ENSEMBLE GUIDANCE. A NON 00Z NAM BLEND SHOWS SIMILARLY WITH THIS SYSTEM. ...CLOSED LOW ENTERING THE PAC NW TODAY AND SETTLING IN ACROSS THE CNTRL ROCKIES/UINTA WED INTO THU... ...WEAK SURFACE LOW ACROSS THE TX/OK PANHANDLES MOVING INTO THE SRN/CNTRL PLAINS THU NIGHT... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/12Z ECMWF BLEND CONFIDENCE: AVERAGE THE BIGGEST DIFFERENCES WITH THIS SYSTEM ARE BY 00Z/19 WHEN THE 00Z NAM LIFTS THE FRONT EDGE OF THE CLOSED LOW FASTER INTO THE PLAINS COMPARED TO THE REMAINING MODEL CONSENSUS. GIVEN LITTLE TO NO TIMING TRENDS HAVE BEEN OBSERVED IN THE ENSEMBLE SPAGHETTI HEIGHTS WITH THIS SYSTEM...AND RELATIVE CONSISTENCY WITH THE ECMWF...NEAR THE 00Z ECMWF IS PREFERRED. THE 00Z GFS SLOWED FROM ITS 12Z RUN AND WHILE STILL AHEAD OF THE 00Z ECMWF...A BLEND OF THE GFS/ECMWF REPRESENTS CLOSER TO THE MIDDLE OF THE LATEST ENSEMBLE SPREAD THROUGHOUT THE 84 HR SHORT RANGE FORECAST PERIOD ENDING 12Z/19. WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/ WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/ OTTO