MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1234 AM EDT TUE JUN 24 2014 VALID JUN 24/0000 UTC THRU JUN 27/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ================================================== 12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES ================================================== NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. ================================================== ...AMPLIFYING LARGE SCALE TROUGHING IN THE WEST SPILLING INTO THE NORTHERN PLAINS... PREFERENCE: BLEND OF 00Z GFS/12Z ECMWF A MEDIUM WAVELENGTH TROUGH WILL DIG OVER THE WESTERN U.S...DOWNSTREAM OF A STRONGER CLOSED LOW APPROACHING THE PACIFIC NORTHWEST. MODEL AGREEMENT IS FAIRLY STRONG...ESPECIALLY AMONG THE OPERATIONAL AND ENSEMBLE MEMBERS OF THE GFS AND ECMWF. THE NAM IS CONSIDERED JUST SLIGHTLY TOO FAST BY DAY 3...AND IS NOT QUITE AS DEEP AT THE BASE OF THE TROUGH OVER THE SOUTHWEST U.S. AT THAT TIME. ...MUCH OF THE CENTRAL AND EASTERN U.S... PREFERENCE: BLEND OF 00Z GFS/12Z ECMWF THE GFS AND ECMWF ARE HANDLING SOME SMALL SCALE AND LOW AMPLITUDE WAVES WITH RELATIVE SIMILARITY OVER THE WESTERN GREAT LAKES. THE ECMWF ENSEMBLE MEAN MAY BE THE BEST OPTION FOR THE LARGER SCALE TROUGH LIFTING THROUGH THE EASTERN AND NORTHEASTERN U.S...BUT TO APPROXIMATE THIS WE CAN RECOMMEND BLENDING THE OPERATIONAL GFS/ECMWF. THE ECMWF WAS SLIGHTLY FAST AND LESS AMPLIFIED THAN CONSENSUS. THE GFS CONTINUED TO STRAY NORTH OF CONSENSUS WITH THE SURFACE REFLECTION...LOW PRESSURE PASSING THROUGH THE MID ATLANTIC AND SOUTHERN NEW ENGLAND. THE NAM MAY HAVE SOME UTILITY THROUGH DAY 2...BUT APPEARS TOO FLAT ALONG THE COAST BY DAY 3...AND TOO DEEP OVER THE GREAT LAKES. ...GULF COASTAL STATES... PREFERENCE: BLEND OF 00Z NAM/GFS WITH 12Z ECMWF THROUGH DAY 3 A LOW LEVEL RIDGE WILL REMAIN CENTERED IN THE EASTERN GULF OF MEXICO...WITH A RICH FEED OF MOISTURE CIRCULATING AROUND IT AND KEEPING THE FORECAST WET OVER THE GULF STATES AND FLORIDA. THE MODELS HANDLE THE RIDGE SIMILARLY...EXCEPT FOR THE UKMET WHICH HAS MORE AMPLIFIED LOW LEVEL RIDGING DEEPER INLAND IN THE MISSISSIPPI VALLEY. THE 12Z CANADIAN WAS ALSO SOMEWHAT LESS DESIRABLE WITH SOME CONVECTIVE FEEDBACK OVER THE SOUTHERN PLAINS AND LESS PRECIPITATION FORECAST ALONG THE GULF COAST. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... BURKE