MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 238 PM EDT TUE JUL 22 2014 VALID JUL 22/1200 UTC THRU JUL 26/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES MID LEVEL LOW SLOWLY RETROGRADING OVER THE GULF COAST STATES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z NAM BLEND CONFIDENCE: ABOVE AVERAGE THE MODELS AGREE ON WEAKENING THIS FEATURE ALONG WITH INCREASING SHEARING AS THE LOW SLOWLY RETROGRADES WWD ALONG THE GULF COAST. THE 00Z UKMET/CMC APPEAR TOO WEAK WITH THE 500 MB LOW COMPARED TO THIS MORNINGS 12Z RAOB DATA...AND ARE ALSO THE WEAKEST WITH THIS LOW AS IT TRACKS WWD INTO SOUTH TEXAS...BUT THEIR 12Z CYCLES APPEAR MUCH BETTER. ON THE OTHER SIDE...THE 12Z NAM WHILE INITIALIZED WELL...IS THE SLOWEST OF THE DETERMINISTIC MODEL SUITE. THE 12Z ECMWF COMPARES FAVORABLY TO THE REMAINING NON NAM CONSENSUS HAVING MADE LITTLE CHANGE FROM ITS 00Z RUN. THEREFORE...A NON 12Z NAM CONSENSUS OF MODELS IS PREFERRED DUE TO THEIR PLACEMENT IN THE MIDDLE OF THE DETERMINISTIC/ENSEMBLE SPREAD. CLOSED LOW PASSING THROUGH THE NORTHWEST WED/THU SURFACE LOW PRESSURE DEVELOPING IN THE LEE OF THE NORTHERN ROCKIES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z NAM / 12Z ECMWF / 12Z UKMET BLEND CONFIDENCE: AVERAGE THE 12Z GFS IS SOUTH OF THE REMAINING DETERMINISTIC/ENSEMBLE CONSENSUS REGARDING THE CLOSED LOW AS IT MOVES THROUGH ALBERTA INTO SASKATCHEWAN...WITH THE 12Z GFS ALSO SHOWING UP FASTER WITH THE PROGRESSION OF THE CLOSED LOW. THESE DIFFERENCES BEGIN TO APPEAR AROUND 12Z/24 AND GROW WITH TIME. THE NAM/ECMWF SHOW THE BEST AGREEMENT TO THE ENSEMBLE MEANS AND LIE IN THE MIDDLE OF THE MODEL SPREAD REGARDING THE 500 MB LOW CENTER AND THE CORRESPONDING SURFACE LOW TRACKING ACROSS THE CNTRL/NRN PLAINS. THE 12Z ECMWF SHOWS VERY LITTLE CHANGE HERE FROM ITS 00Z RUN...AND IS MATCHED BY THE 12Z UKMET. BROADER UPPER LEVEL TROUGH CROSSING THE GREAT LAKES AND INTO THE NORTHEAST BY FRI MORNING COLD FRONT CROSSING THE OHIO VALLEY AND MID-ATLANTIC REGION ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE ALL THE MODELS SHOW GOOD AGREEMENT HERE SO WILL PREFER A GENERAL MODEL COMPROMISE TO IRON OUT SMALLER SCALE DIFFERENCES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO