MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1243 AM EDT MON JUN 15 2015 VALID JUN 15/0000 UTC THRU JUN 18/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. TROPICAL DISTURBANCE MOVING TOWARDS TX ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS...12Z ECMWF...12Z UKMET BLEND CONFIDENCE: SLIGHTLY BELOW AVERAGE/SEE NHC OUTLOOKS DESPITE INITIAL UNCERTAINTY WITH LOW CENTER PLACEMENT...ENSEMBLE SCATTER PLOT LOWS CONTINUE TO BE WELL CLUSTERED OVER THEIR PAST 3 CYCLES...AND HAVE SHOWN A SUBTLE SHIFT TO THE SOUTH VALID 12Z/16 ALONG THE SOUTH TEXAS COAST COMPARED TO YESTERDAY. THE 00Z GFS...12Z ECMWF AND 12Z UKMET SHOW AGREEMENT WITH THIS POSITION AND THIS POSITION IS ALSO IN LINE WITH THE NHC COORDINATED POSITION FROM SUNDAY AFTERNOON. THE NHC CONTINUES TO MONITOR THIS SYSTEM AND FORECAST AN 80 PERCENT CHANCE OF TROPICAL CYCLONE FORMATION WITHIN THE NEXT 48 HOURS. SEE THE LATEST TROPICAL OUTLOOKS FROM THE NATIONAL HURRICANE CENTER REGARDING THE CURRENT STATUS OF THIS SYSTEM AND REFER TO WPC PRECIPITATION PRODUCTS FOR INFORMATION RAINFALL POTENTIAL. CLOSED LOW NEAR VANCOUVER ISLAND THROUGH MID WEEK ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 12Z ECMWF BLEND CONFIDENCE: SLIGHTLY BELOW AVERAGE THE 00Z NAM IS SLOWEST TO MOVE A CLOSED LOW INLAND FROM NEAR VANCOUVER ISLAND WHILE THE 12Z UKMET/CMC ARE FASTEST. ENSEMBLE SPAGHETTI HEIGHTS CONTINUE TO SHOW A FAIR AMOUNT OF SPREAD BUT CLEARLY INDICATE THE UKMET/CMC ON THE FASTER EDGE OF THE ENSEMBLE SPREAD. THE MIDDLE OF THE ENSEMBLE AND DETERMINISTIC SPREAD IS BEST REPRESENTED BY THE 00Z GFS/12Z ECMWF WITH THE 00Z GFS SHOWING VERY GOOD RUN TO RUN CONTINUITY AND THE 12Z ECMWF HAVING TRENDED TOWARD THE GFS OVER ITS PAST DAY OF RUNS. LOW AMPLITUDE SHORTWAVE REACHING THE NRN PLAINS TUE EVENING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS / 12Z ECMWF BLEND CONFIDENCE: AVERAGE WHILE DIFFERENCES AT 500 MB ARE MINIMAL...THERE IS GREATER MODEL SPREAD FROM 700 MB TO THE SURFACE. THE NAM IS A BIT STRONGER AND DISPLACED NWD WITH THE SURFACE LOW FROM BETTER ENSEMBLE CLUSTERING. THE 00Z GFS AND 12Z ECMWF ARE BEST MATCHED TO THE ENSEMBLE MEANS AND EACH OTHER FOR THIS SYSTEM. TROUGH OVER CENTRAL CANADA WED AND COLD FRONTAL POSITION INTO THE NORTHERN PLAINS WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 70% 12Z ECMWF / 30% 00Z GFS CONFIDENCE: AVERAGE THE ENSEMBLE MEANS SHOW BETTER SUPPORT FOR A FRONTAL TIMING CLOSE TO THE 12Z ECMWF WITH THE 00Z GFS THE NEXT CLOSEST THOUGH A BIT FASTER THAN THE 12Z ECMWF. THESE MODELS ARE IN THE MIDDLE OF THE LATEST DETERMINISTIC SPREAD. SHORTWAVE MOVING EAST FROM THE CNTRL PLAINS MON-TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THE MODELS NOW SHOW SIMILARLY WITH THIS SYSTEM. FRONT CROSSING NEW ENGLAND TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE HANDLES THIS SYSTEM RELATIVELY SIMILARLY. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO