MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1132 PM EST SAT FEB 22 2014 VALID FEB 23/0000 UTC THRU FEB 26/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. LONGWAVE TROUGH APPROACHING THE WEST COAST BY WEDNESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF/CANADIAN COMPROMISE CONFIDENCE: AVERAGE MODELS HAVE SHOWN FAIRLY GOOD AGREEMENT AND RUN TO RUN CONTINUITY. USING THE 12Z GLOBAL ENSEMBLE LOW CLUSTERING AS A GUIDE, THE 00Z GFS/12Z CANADIAN/12Z ECMWF HAVE THE MOST SUPPORT, SO SUPPORT A COMPROMISE OF THEIR SOLUTIONS WITH ABOVE AVERAGE CONFIDENCE CONSIDERING THE UPPER LEVEL SYSTEM'S AMPLIFIED AND SLOWLY PROGRESSIVE NATURE. TROUGH AMPLIFYING NEAR THE GREAT LAKES TUE/WED LOW APPROACHING NORTHERN NEW YORK WED MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF/CANADIAN COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 00Z NAM/12Z UKMET ARE QUICKER/WEAKER WITH A SHORTWAVE PIVOTING THROUGH THE GREAT LAKES TUESDAY NIGHT WHILE THE SOUTHERN PERIPHERY OF THE POLAR VORTEX MOVES SOUTHWARD THROUGH HUDSON BAY. AS THE SHORTWAVE IS MOVING UNDER THE BASE OF THE MID- TO UPPER-LEVEL LOW, IT IS MORE LIKELY TO SHARPEN AND MOVE SLOWER EASTWARD...WHICH LED TO THE DISCOUNTING OF THE NAM/UKMET SOLUTIONS. IN REGARDS TO THE SURFACE LOW PROGRESSION TOWARDS NORTHERN NEW YORK WEDNESDAY MORNING, THE GUIDANCE WAS SIMILAR. TO ACCOUNT FOR THE ISSUES ALOFT, PREFER A COMPROMISE OF THE 00Z GFS/12Z ECMWF/12Z CANADIAN SOLUTIONS WITH ABOVE AVERAGE CONFIDENCE CONSIDERING THE SYNOPTIC PATTERN THE SYSTEM IS EMBEDDED WITHIN. SHORTWAVE MOVING THROUGH SRN US SUNDAY-TUESDAY LOW IN THE LEE OF THE ROCKIES MONDAY/TUESDAY CYCLOGENESIS OFFSHORE THE SOUTHEAST TUE NGT/WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF COMPROMISE CONFIDENCE: AVERAGE THE GUIDANCE IS NOW AGREEABLE AT THIS SYSTEM MOVES INTO THE SOUTHERN PLAINS AND BRIEFLY SPURS A LOW PRESSURE AREA/LEE LOW TO MOVE FROM THE FRONT RANGE OF THE ROCKIES INTO NORTHERN TEXAS TUESDAY. AS THE SYSTEM APPROACHES THE SOUTHEAST COAST AS A LOW AMPLITUDE FEATURE, IT SPURS SURFACE LOW DEVELOPMENT IN THE GUIDANCE. THE BEST 12Z GLOBAL ENSEMBLE CLUSTERING SPLITS THE DIFFERENCE BETWEEN THE 12Z ECMWF AND 00Z GFS, SO A COMPROMISE OF THE TWO IS PREFERRED WITH AVERAGE CONFIDENCE CONSIDERING THE SYSTEM'S LOW AMPLITUDE AND PROGRESSIVE NATURE. SOUTHWEST CANADA-GREAT LAKES SHORTWAVE SUNDAY-TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THE GUIDANCE IS IN GOOD AGREEMENT WITH THIS SYSTEM. PREFER A GENERAL MODEL COMPROMISE TO DEAL WITH ANY LINGERING DETAIL ISSUES WITH AVERAGE CONFIDENCE CONSIDERING ITS PROGRESSIVE AND WEAKENING NATURE. SHORTWAVE SWINGING ACROSS NEW ENGLAND MONDAY COASTAL LOW DEVELOPMENT SUNDAY NIGHT/MONDAY MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF COMPROMISE CONFIDENCE: AVERAGE ALOFT, THE GUIDANCE IS IN FAIRLY GOOD AGREEMENT. THE GLOBAL ENSEMBLE SPREAD AT THE SURFACE WITH THIS SYSTEM HAS NARROWED AND REMAINED ESSENTIALLY IN THE SAME SPOT BETWEEN THEIR 21/12Z AND 22/12Z RUNS, WHICH MOST SUPPORTS THE 00Z GFS/12Z ECMWF SOLUTIONS. THIS COMPROMISE IS PREFERRED WITH AVERAGE CONFIDENCE CONSIDERING THE LINGERING SPREAD IN THE GUIDANCE. www.wpc.ncep.noaa.gov/html/model2.shtml... ROTH