MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 234 PM EDT WED AUG 19 2015 VALID AUG 19/1200 UTC THRU AUG 23/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS APPEAR MINIMAL AND SHOULD NOT DEGRADE SHORT RANGE FORECASTS. FRONT/TROUGH IN THE NORTHEAST FRIDAY/SATURDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE BRINGS A FRONT INTO THE REGION WHICH BEGINS TO WASH OUT AS IT STALLS NORTH OF A POSSIBLE TROPICAL/SUBTROPICAL CYCLONE LOCATED NEAR BERMUDA. THE SYNOPTIC SETUP APPEARS VAGUELY SIMILAR TO THAT SEEN DURING THE EXTRATROPICAL PHASE OF SUB T.D. #22 (OCTOBER 10-14, 2005), THOUGH TWO MONTHS EARLIER AND WITH A CYCLONE FARTHER OFFSHORE. WITH THE SYSTEM NEAR BERMUDA, THE 12Z ECMWF POSITION APPEARS REASONABLE. A GENERAL MODEL COMPROMISE IS PREFERRED WITH THE LINGERING FRONTAL BOUNDARY ACROSS NEW ENGLAND WITH ABOVE AVERAGE CONFIDENCE. UPPER TROUGH/CYCLONE NEAR THE CENTRAL US/CAN BORDER SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-ECMWF COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z ECMWF IS SHARPER ALOFT WITH THIS SYSTEM, WITH A SURFACE LOW MORE SOUTHERLY WITHIN MN SATURDAY EVENING, WITHIN THE SOUTHERN FRINGE OF THE 00Z GLOBAL ENSEMBLE SPREAD. WITH A BROAD UPSTREAM RIDGE, BELIEVE THE ECMWF IS LIKELY TOO SHARP. A COMPROMISE OF THE 12Z RUNS OF THE GFS/UKMET/CANADIAN/NAM APPEARS REASONABLE, AND IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. UPPER LOW/SHEAR LINE RETROGRADING INTO NORTHERN MEXICO ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE SHOWS GOOD AGREEMENT WITH THIS SYSTEM. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH