MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1250 PM EDT TUE APR 01 2014 VALID APR 01/1200 UTC THRU APR 05/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. MID-LEVEL SHORTWAVE APPROACHING THE WEST COAST ON THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THE GUIDANCE SHOWS GOOD AGREEMENT WITH THIS SYSTEM. A GENERAL MODEL COMPROMISE IS PREFERRED TO DEAL WITH ANY LINGERING DETAIL ISSUES WITH ABOVE AVERAGE CONFIDENCE CONSIDERING THE MINIMAL SPREAD SEEN IN THE DETERMINISTIC/ENSEMBLE MEAN GUIDANCE. UPPER TROUGH ADVANCING EWD FROM THE WEST COAST THROUGH FRI ASSOCIATED SURFACE LOW/FRONT IN THE CENTRAL U.S. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS / 00Z ECMWF COMPROMISE CONFIDENCE: AVERAGE THERE IS SOMEWHAT ABOVE AVERAGE MODEL SPREAD WITH THIS SYSTEM AS ONE HEADS TO THE WEEKEND...CONCERNING A POTENTIAL CLOSED MID-LEVEL LOW OVER THE MIDWEST BY FRI MORNING. THE 00Z UKMET STANDS OUT AS AN OUTLIER IN NEVER DEVELOPING A CLOSED OFF LOW...AND IS THE MOST PROGRESSIVE OF THE DETERMINISTIC MODELS WITH THE SPEED OF THE SYSTEM DURING THE DAY ON FRI. THERE HAS GENERALLY BEEN A TREND TO BE FASTER OVER THE PAST THREE 12/00Z MODEL CYCLES IN THE GFS/UKMET/CMC BUT THE ECMWF HAS BEEN VERY CONSISTENT. CURRENT ENSEMBLE SPREAD SHOWS THE ECMWF MEMBERS NORTH OF THE GEFS MEMBERS BY 12Z FRI OVER IOWA/MINNEOSTA WITH THE 540 DM LOW AT 500 MB...BUT THERE IS ABOVE AVERAGE SPREAD IN THE ENSEMBLE MEMBERS IN ALL DIRECTIONS...WITH THE 12Z NAM TOWARD THE SRN EDGE OF THE SPREAD. IN THE MIDDLE...BUT TOWARD THE NORTH AND WEST SIDE OF THE ENSEMBLE LOWS CENTROID...IS THE GFS/ECMWF POSITION...WHICH WAS WHERE THE MODELS TRENEDED WITH A SIMILAR SETUP FROM THIS PREVIOUS WEEKEND. UPPER TROUGH / SURFACE CYCLONE DEPARTING FROM THE GREAT LAKES TODAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE HANDLES THE CYCLONE MOVING OUT OF MN/WI/MI REASONABLY WELL AS IT MOVES INTO ERN CANADA...WHICH TRANSLATES TO A REASONABLY SIMILAR FRONTAL PROGRESSION. A GENERAL MODEL COMPROMISE IS PREFERRED TO DEAL WITH ANY LINGERING DETAIL ISSUES. www.wpc.ncep.noaa.gov/html/model2.shtml... OTTO