MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 238 AM EDT SAT APR 22 2017 VALID APR 22/0000 UTC THRU APR 25/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES/CONFIDENCE INTERVALS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. SYSTEM MOVING THROUGH THE NORTHWEST INTO THE WEST MONDAY INTO TUESDAY ~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-NAM COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 00Z NAM IS A BIT STRONGER THAN THE OTHER GUIDANCE WITH THIS SYSTEM AS IT TRACKS THROUGH THE NORTHWEST INTO THE GREAT BASIN, ONE OF ITS OLDER BIASES. AS THE FLOW PATTERN IN WHICH IT IS EMBEDDED IS ONE OF LOW AMPLITUDE, THE NAM IS LIKELY TOO STRONG ALOFT. A COMPROMISE OF THE 00Z CANADIAN/00Z UKMET/00Z GFS/00Z NAM APPEARS FINE, WHICH IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. SYSTEM MOVING INTO THE NORTHWEST SUNDAY NIGHT SYSTEM MOVING BY THE CENTRAL US/CANADIAN BORDER MON/TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE IS NOW IN GOOD AGREEMENT WITH THIS FEATURE. A COMPROMISE OF THE AVAILABLE GUIDANCE, SIMILAR TO THE PARALLEL VERSION OF THE NATIONAL BLEND OF MODELS, IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. DEEP CYCLONE IN THE SOUTHEAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CANADIAN COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 00Z CANADIAN IS UP TO ITS OLD TRICKS AS IT APPEARS TO FORM A TROPICAL ENTITY IN THE FL STRAITS WHICH ROTATES INTO NC AS A DEEPER CYCLONE THAN SEEN IN THE OTHER GUIDANCE. IF THAT WEREN'T ENOUGH, IT'S ALSO SLOW AND DEEP WITH THIS SYSTEM ALOFT BY LATE MONDAY/EARLY TUESDAY, STRAYING FAR FROM THE DETERMINISTIC CONSENSUS AND FITTING ANOTHER ONE OF ITS KNOWN BIASES. A COMPROMISE OF THE 00Z GFS/00Z NAM/00Z UKMET/00Z ECMWF IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE. WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/ WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/ ROTH