MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1148 PM EST THU JAN 26 2017 VALID JAN 27/0000 UTC THRU JAN 30/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SHORTWAVE OVER THE SWRN U.S. THIS MORNING...REACHING NWRN MEXICO BY SAT EVENING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 12Z ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE MODELS HAVE CONVERGED SINCE YESTERDAY BUT SOME MINOR DIFFERENCES REMAIN ACROSS NWRN MEXICO STARTING SUN MORNING. ENSEMBLE SPREAD REMAINS MODERATE BUT SHOWS THE 12Z UKMET TOWARD THE WRN EDGE OF THE GUIDANCE AND THE 00Z NAM FARTHEST EAST THROUGH MON. THE ENSEMBLE MEANS SUPPORT A 00Z GFS AND 12Z ECMWF BLEND ALTHOUGH DIFFERENCES ARE NOT TOO LARGE OVERALL WITH ANY OF THE MODELS. SERIES OF MID-LEVEL SHORTWAVES DROPPING SEWD ACROSS THE GREAT LAKES THROUGH MON MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 12Z ECMWF BLEND CONFIDENCE: SLIGHTLY BELOW AVERAGE RUN TO RUN CONSISTENCY HAS BEEN POOR IN GENERAL...BUT HAS BEEN WORST IN THE CMC AND UKMET. CONFIDENCE REMAINS A BIT BELOW AVERAGE WITH THE INDIVIDUAL SHORTWAVE DETAILS CONCERNING THREE OF THE MORE TRACKABLE FEATURES TO SWEEP ACROSS THE LAKES THROUGH MON...WITH THE THIRD BEING THE MOST AMPLIFIED. THE AMPLITUDE OF THE ENSEMBLE MEANS IS CLOSEST TO THE 00Z GFS/12Z ECMWF BUT SOME TIMING DIFFERENCES EXIST WITH THE 00Z GFS FASTER BEYOND 12Z/29. A BLEND OF THE 00Z GFS AND 12Z ECMWF REPRESENTS THE CLOSEST TO THE MIDDLE OF THE AVAILABLE GUIDANCE WHILE SHOWING THE LEAST CHANGES FROM RUN TO RUN. MID-LEVEL SHORTWAVE DIVING SOUTH THROUGH THE PLAINS FRI AND REACHING THE CNTRL GULF COAST FRI NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 12Z ECMWF BLEND CONFIDENCE: AVERAGE BETTER CONVERGENCE IN THE MODELS EXISTS TODAY COMPARED TO YESTERDAY. THE 12Z CMC IS QUICKLY DISCOUNTED AS IT IS OFF WITH ITS F012 HR FORECAST OF THE VORTICITY MAX OVER BRITISH COLUMBIA. AS THE VORT DROPS SOUTH THROUGH THE PLAINS...THE NAM APPEARS TUCKED CLOSER TOWARD LOWER HEIGHTS...WITH THE 00Z GFS AND 12Z ECMWF NEAR ONE ANOTHER AND THE 12Z UKMET FARTHER OUT OVER THE TX/OK PANHANDLES BY 12Z/28. THE SHARPNESS TO THE LONGWAVE TROUGH AXIS IN THE 00Z GFS AND 12Z ECMWF APPEARS BETTER CORRELATED TO THE ENSEMBLE MEANS COMPARED TO THE REMAINING AVAILABLE GUIDANCE. COLD FRONT REACHING THE PACIFIC NORTHWEST ON SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 12Z ECMWF BLEND CONFIDENCE: AVERAGE THE 00Z GFS IS A BIT FASTER WITH THIS FRONT COMPARED TO THE 00Z ECMWF. THERE IS NEAR EQUAL SUPPORT FOR BOTH MODEL IDEAS...BUT GIVEN THE DIFFERENCES ARE RELATIVELY MINOR...A BLEND OF THE TWO IS RECOMMENDED TO IRON OUT THESE DIFFERENCES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO