MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 227 PM EDT MON MAY 18 2015 VALID MAY 18/1200 UTC THRU MAY 22/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ STRONG HEIGHT FALLS PUSHING THROUGH THE FOUR CORNERS REGION TONIGHT AND SHEARING EASTWARD INTO THE CENTRAL PLAINS BY WEDNESDAY WEAK SURFACE WAVE TRACKING EWD FROM THE SRN HIGH PLAINS TUE NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z NAM/ECMWF/UKMET BLEND CONFIDENCE: AVERAGE FAIRLY GOOD MODEL AGREEMENT EXISTS WITH TIMING/STRENGTH OF SHORTWAVE ENERGY EJECTING INTO THE PLAINS FROM THE FOUR CORNERS REGION. THE 12Z GFS HOWEVER...MAY BE DEVELOPING CONVECTIVE FEEDBACK TONIGHT INTO TUESDAY ACROSS WRN TO NRN TEXAS WHICH IMPACTS THE SURFACE FRONTAL PLACEMENT AND AN AREA OF LOW PRESSURE EXPECTED TO TRACK FROM THE TEXAS PANHANDLE TOWARD THE LOWER MISSISSIPPI VALLEY. THE ENSEMBLE MEANS AGREE WELL WITH THE 12Z NAM AND 12Z UKMET POSITION...WITH THE 00Z ECWMF ON THE NRN SIDE OF THE MODEL SPREAD...AND THE 12Z ECMFF SHIFTING SOUTHWARD SLIGHTLY TO BE IN BETTER AGREEMENT WITH THE ENSEMBLE MEANS. COLD FRONT MOVING THROUGH THE OHIO VALLEY TODAY...REACHING THE EAST COAST TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW SIMILARLY WITH THIS SYSTEM. ADDITIONAL HEIGHT FALLS DROPPING INTO THE MEAN TROUGH POSITION OFF OF CALIFORNIA WEDNESDAY INTO THURSDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE NO MAJOR DIFFERENCES NOTED WITH THE ADDITIONAL HEIGHT FALLS THAT DROP INTO THE MEAN TROF POSITION OFF THE CALIFORNIA COAST FROM TUESDAY INTO EARLY THURSDAY...NOR ANY SIGNIFICANT TRENDS NOTED IN THE 500MB ENSEMBLE SPAGHETTI HEIGHT PLOTS. THE LATEST ENSEMBLE MEANS AGREE BEST WITH THE 12Z MODEL SUITE...WITH THE 12Z UKMET/CMC ADJUSTING TOWARD THE NAM/GFS/ECMWF BY THU EVENING WITH THE CENTER OF THE CLOSED LOW OVER THE CNTRL CALIFORNIA COAST COMPARED TO THE 00Z UKMET/CMC. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO