MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1234 PM EDT WED APR 22 2015 VALID APR 22/1200 UTC THRU APR 26/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. CLOSED LOW MOVING ACROSS NEW ENGLAND THU/FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE DESPITE INDIVIDUAL SHORTWAVES REVOLVING ABOUT THE CENTER OF THIS LARGE CLOSED LOW...THE MODELS SHOW BROAD AGREEMENT SUCH THAT A GENERAL MODEL COMPROMISE CAN BE USED. SHORTWAVE EJECTING INTO THE SRN/CNTRL PLAINS FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS / 00Z ECMWF COMPROMISE CONFIDENCE: AVERAGE TRENDS HAVE BEEN SLOWER OVER THE PAST DAY OF MODEL RUNS WITH THIS FEATURE...CURRENTLY OVER THE ERN PACIFIC BUT FORECAST TO REACH THE SRN/CNTRL PLAINS ON FRI. MODEL DIFFERENCES ARE NOT TOO LARGE BUT A BLENDED GFS AND ECMWF REPRESENT THE MIDDLE OF THE LATEST DETERMINISTIC SPREAD WITH AGREEMENT TOWARD CLUSTERING THE ENSEMBLE SCATTER SURFACE LOW PLOTS. CLOSED MID LEVEL LOW NEAR THE PACIFIC NORTHWEST FRI/SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 00Z UKMET COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE UKMET IS FASTER WITH THIS UPPER TROUGH WHILE THE REMAINING MODELS AND ENSEMBLE MEANS SUPPORT A SOMEWHAT SLOWER PROGRESSION OF THIS FEATURE BY LATE FRI ACROSS THE NORTHWEST. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO