MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 136 AM EST WED FEB 11 2015 VALID FEB 11/0000 UTC THRU FEB 14/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. UPPER TROUGH APPROACHING THE PACIFIC NORTHWEST FRI EVE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: ECMWF/UKMET COMPROMISE CONFIDENCE: SLIGHTLY BELOW AVERAGE THE GUIDANCE BRINGS A SHORTWAVE OF VARIOUS DEPTH/PROGRESSION INTO THE PACIFIC NORTHWEST FRIDAY NIGHT. THE 21Z SREF/18Z GEFS MEANS DON'T APPEAR TO HAVE MUCH SHORTWAVE ENERGY AT ALL, SHOWING A RIDGE-LIKE ORIENTATION LATE FRIDAY NIGHT. THERE HAS BEEN A DEFINITE TREND IN THE NON-NCEP GUIDANCE TOWARDS A STRONGER SHORTWAVE, THOUGH THE GUIDANCE IN GENERAL CAN HAVE A BIAS OF DENTING IN THE TOP OF A RIDGE TOO MUCH -- SUPERGEOSTROPHIC/FAST FLOW OVER THE TOP OF THE RIDGE TENDS TO MINIMIZE AMPLITUDE AND LEAD TO A QUICK SOLUTION. KEEPING THIS IN MIND AND THE RECENT GUIDANCE SHIFT, A COMPROMISE OF THE ECMWF/UKMET IS ADVISED WITH SLIGHTLY BELOW AVERAGE CONFIDENCE. STRONG MID-LEVEL CYCLONE MOVING TOWARDS THE GREAT LAKES SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z CANADIAN IS ON THE FAST SIDE OF GUIDANCE WITH THE FRONTAL PROGRESSION ACROSS THE MISSISSIPPI VALLEY DUE TO SLIGHTLY GREATER MID-LEVEL HEIGHT FALLS ACROSS THE PLAINS, WHILE THE 00Z UKMET IS ON THE SLOW SIDE DUE TO ITS SLIGHTLY HIGHER MID-LEVEL HEIGHTS. WHILE THE 21Z SREF/12Z ECMWF ENSEMBLE MEAN SOLUTIONS SUPPORT A SLOWER FRONTAL PROGRESSION, THE 00Z GEFS MEAN HAS SPED UP THIS BOUNDARY'S PROGRESSION. A COMPROMISE OF THE GFS/ECMWF SPLITS THE DIFFERENCE IS PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE. TROUGH AMPLIFYING FROM THE GREAT LAKES TO THE EAST THU-FRI SHORTWAVE DROPPING INTO NORTHWEST MEXICO THU/FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE IS IN GOOD AGREEMENT WITH THESE SYSTEMS. A GENERAL MODEL COMPROMISE SHOULD DEAL EFFECTIVELY WITH ANY RESIDUAL DETAIL ISSUES. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH