MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 131 AM EST WED FEB 26 2014 VALID FEB 26/0000 UTC THRU MAR 01/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. VORT LOBE IN SOUTHWEST CANADA FRI NGT/SAT AM MID-LEVEL HEIGHT LOWERING NEAR WRN & CENTRAL US/CAN BORDER ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: CANADIAN/ECMWF COMPROMISE CONFIDENCE: AVERAGE THE 00Z UKMET IS MORE EAGER TO LOWER HEIGHTS ACROSS MONTANA/NORTH DAKOTA FRIDAY NIGHT INTO SATURDAY MORNING THAN THE OTHER GUIDANCE, WITH THE NCEP GUIDANCE SHOWING MORE HEIGHT LOWERING ACROSS THE PACIFIC NORTHWEST AND THE 00Z CANADIAN/00Z ECMWF SOLUTIONS LYING SOMEWHERE IN BETWEEN. THE LOWERING OF HEIGHTS ACROSS THE REGION IS DUE TO THE RETROGRESSION OF A BURGEONING AND ELONGATING MID-LEVEL GYRE ASSOCIATED WITH THE NORTH AMERICAN PORTION OF THE POLAR VORTEX ACROSS SOUTHERN CANADA AND A SHORTWAVE MOVING AROUND ITS WESTERN PERIPHERY. OVERALL THOUGH, THESE DIFFERENCES ARE RELATIVELY SMALL FOR A FORECAST THREE DAYS INTO THE FUTURE. TO DEAL WITH THE ISSUE, PREFER A GENERAL MODEL COMPROMISE -- CLOSEST TO A 00Z CANADIAN/00Z ECMWF COMPROMISE -- WITH AVERAGE CONFIDENCE DUE TO THE EXISTING MODEL SPREAD AND THE RETROGRESSIVE NATURE OF THE FLOW ACROSS SOUTH-CENTRAL AND SOUTHWEST CANADA -- WHICH THE GUIDANCE CAN STRUGGLE WITH FROM TIME TO TIME. ANOMALOUSLY DEEP CYCLONE APPROACHING CA LATE FRIDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: CLOSEST TO THE 00Z ECMWF CONFIDENCE: AVERAGE THERE ARE SMALL PROGRESSION ISSUES SEEN AMONGST THE GUIDANCE, WITH THE 00Z GFS/00Z GEFS MEAN/00Z NAM SLIGHTLY QUICKER THAN THE OTHER GUIDANCE, WITH THE 21Z SREF MEAN/00Z ECMWF LYING IN THE MIDDLE PROGRESSION-WISE, THOUGH THE SREF'S UPPER SOLUTION IS LIKELY TOO WEAK. THE 00Z ECMWF SPLITS THE DIFFERENCE BETWEEN THE VARIOUS DETERMINISTIC GUIDANCE AND LIES REASONABLY CLOSE TO THE 12Z GLOBAL ENSEMBLE LOW CLUSTERING. A SOLUTION CLOSEST TO THE 00Z ECMWF IS PREFERRED WITH AVERAGE CONFIDENCE CONSIDERING ITS RELATIVELY PROGRESSIVE NATURE AND THE MODEST SPREAD IN THE GUIDANCE. SOUTHERN STREAM SHORTWAVE MOVING THROUGH SRN US WED-FRI LOW NEAR THE RED RIVER OF THE SOUTH THURSDAY/FRIDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE THIS SYSTEM IS EXPECTED TO MOVE OVER THE TOP OF A SOUTHERN STREAM RIDGE AS IT CROSSES THE ROCKIES BEFORE MOVING THROUGH QUASI-ZONAL/EAST-WEST FLOW TO THE SOUTH OF AN ELONGATED EAST-WEST UPPER TROUGH JUST NORTH OF THE US/CANADIAN BORDER. THE SYNOPTIC PATTERN SHOULD NOT ALLOW IT TO GAIN MUCH AMPLITUDE, RULING THE 00Z UKMET OUT FROM CONSIDERATION. OTHERWISE, THE GUIDANCE IS QUITE AGREEABLE. A NON-UKMET COMPROMISE IS PREFERRED HERE WITH ABOVE AVERAGE CONFIDENCE BASED ON THE SYNOPTIC PATTERN THE SYSTEM IS EMBEDDED WITHIN. DEEP CYCLONE SWEEPING BY THE GREAT LAKES/NEW ENGLAND WED-FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THE GUIDANCE IS SHOWING A REASONABLE PROGRESSION WITH THIS ANOMALOUSLY DEEP MID-LEVEL SHORTWAVE FOR LATE FEBRUARY AND ITS CORRESPONDING SURFACE LOW. A GENERAL MODEL COMPROMISE IS ADVISED WITH AVERAGE CONFIDENCE CONSIDERING ITS PROGRESSIVE NATURE. SHORTWAVE MOVING THROUGH THE NRN MID-ATLANTIC REGION WED MORNING SURFACE LOW BYPASSING NEW ENGLAND WEDNESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: HIGH THE GUIDANCE IS NOW IN DECENT AGREEMENT SHOWING ONLY SUBTLE DEPTH/TIMING DIFFERENCES REMAINING. A GENERAL MODEL COMPROMISE IS PREFERRED TO SMOOTH OUT ANY REMAINING DETAIL DIFFERENCES WITH HIGH CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... ROTH