MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 150 AM EST SUN MAR 05 2017 VALID MAR 05/0000 UTC THRU MAR 08/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS APPEAR NEGLIGIBLE WITH RESPECT TO THEIR FORECASTS WEAKENING MID-UPPER LEVEL TROUGH TRACKING ALONG THE GULF COAST THROUGH MONDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE WITH THE 00Z CMC ADJUSTING FASTER WITH THE MID-LEVEL TROUGH AS IT TRACKS INTO THE WRN GULF OF MEXICO COMPARED TO THE 12Z RUN...ALL OF THE DETERMINISTIC MODELS ARE IN REASONABLE AGREEMENT WITH THIS SYSTEM CONCERNING MASS FIELDS. ENSEMBLE SPAGHETTI HEIGHT CLUSTERING SUPPORTS THE DETERMINISTIC CONSENSUS RESULTING IN A GENERAL MODEL COMPROMISE FOR THE PREFERENCE. WESTERN U.S. LONGWAVE TROUGH EVOLVING INTO CLOSED LOW NEAR NRN ND/MN THROUGH TUE ASSOCIATED COLD FRONT MOVING FROM THE PLAINS TO THE EAST COAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~ PREFERENCE: 00Z NAM/00Z CMC BLEND (NORTHERN TIER OF U.S.) 00Z GFS/00Z ECMWF BLEND (SOUTHERN TIER OF U.S.) CONFIDENCE: SLIGHTLY BELOW AVERAGE THE SURFACE LOW TRACK SHOWS SIMILARLY IN THE LATEST DETERMINISTIC MODELS...AND THE ENSEMBLE SCATTER LOW PLOTS HAVE NOT MADE MAJOR ADJUSTMENTS WITH THEIR PAST FEW CYCLES...AS THE SURFACE LOW TRACKS FROM THE DAKOTAS TO NEAR INTERNATIONAL FALLS MN AND ONWARD INTO S-CNTRL CANADA. HOWEVER...THE 00Z GFS CONTINUES TO APPEAR A BIT TOO FAST WITH THE TIMING OF THE COLD FRONT MOVING THROUGH THE MID-UPPER MISSISSIPPI VALLEY LATE MON EVENING AND AS THE COLD FRONT REACHES THE NORTHEAST. THE GFS IS ALSO ON THE STRONGER SIDE OF THE MODELS WITH ITS 500 MB HEIGHT CORE. DESPITE TRENDING FASTER...THE 00Z ECMWF CONTINUES TO APPEAR TOO SLOW WITH THE COLD FRONT AND TOO WEAK WITH THE 500 MB CORE GIVEN THE ENSEMBLE SPAGHETTI HEIGHTS SUPPORTING TIMING/STRENGTH BETWEEN THE 00Z GFS AND 00Z ECMWF. THE 00Z NAM AND 00Z CMC FAVOR THIS MIDDLE GROUND WITH THE UPPER LOW...SURFACE LOW AND COLD FRONTAL TIMING INTO THE NORTHEAST. THE 00Z CMC ADJUSTED SLOWER WITH THE 500 MB PROGRESSION WHICH APPEARS REASONABLE GIVEN THE LATEST 00Z MODEL SUITE AND THE 00Z GEFS/12Z ECMWF MEAN POSITIONS IN THE MIDDLE OF THE FASTER GFS AND SLOWER ECMWF. HOWEVER...TIMING ISSUES BETWEEN THE 00Z NAM AND 00Z CMC DEVELOP AS THE COLD FRONT REACHES THE LOWER MISSISSIPPI VALLEY. THESE DIFFERENCES RELATE TO THE DEPTH OF THE 500-700 MB TROUGH WITH THE 00Z NAM SLOWEST AND MOST NORTH WITH THE FRONT AND THE REMAINING MODELS FARTHER SOUTH THAN THE NAM. THE 00Z GEFS MEAN AND 12Z ECMWF MEAN SUPPORT A MIDDLE GROUND SIMILARLY REPRESENTED BY THE 00Z GFS AND 00Z ECMWF. ZONAL FLOW INTO THE PACIFIC NORTHWEST TUE/WED SURFACE LOW TRACKING REACHING THE PACIFIC NORTHWEST ON TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/ECMWF/CMC BLEND CONFIDENCE: AVERAGE THE 00Z UKMET STANDS OUT AGAINST THE CONSENSUS WITH THE HANDLING OF A WEAK SHORTWAVE APPROACHING THE PACIFIC NORTHWEST ON TUE IN BEING FASTER. THE REMAINING MODELS DIFFER A BIT WITH TIMING...THE 00Z NAM IS SLOWER TO MOVE THE SURFACE LOW INTO THE COAST WHILE THE 00Z GFS/ECMWF/CMC ARE FASTER. GIVEN TRENDS TOWARD FASTER WITH THE SURFACE LOW AND ONLY A FEW ENSEMBLES MEMBERS SUPPORT THE SLOWER TIMING OF THE 00Z NAM...THE NAM HAS BEEN REMOVED FROM THE PREFERENCE. A BLEND IN THE MIDDLE OF THE REMAINING MODEL CLUSTERING BETWEEN THE 00Z GFS...00Z ECMWF AND 00Z CMC SEEMS REASONABLE. REGARDING THE ONSHORE FLOW COMPONENT INTO THE PACIFIC NORTHWEST THROUGH WED...THE 00Z CMC AND 00Z ECMWF SHOW SIMILAR WITH THE 00Z ECMWF ADJUSTING SOUTH RELATIVE TO ITS PREVIOUS RUN. THE 00Z GFS REMAINS A BIT SOUTH OF THE ECMWF/CMC WITH THE MID-UPPER LEVEL JET AXIS ACROSS THE WEST COAST...BUT THE THREE MODELS REPRESENT THE EDGES OF THE SPECTRUM OUTSIDE OF THE EDGES OF THE DETERMINISTIC MODELS. THE BLENDED POSITION IS IN THE MIDDLE OF THE LATEST ENSEMBLE SPAGHETTI HEIGHTS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO