MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1247 AM EDT MON MAY 01 2017 VALID MAY 01/0000 UTC THRU MAY 04/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...PRELIMINARY MODEL PREFERENCES/CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...DEEP CLOSED LOW LIFTING FROM THE CENTRAL PLAINS ACROSS THE GREAT LAKES THROUGH TUES WITH TRAILING COLD FRONT CROSSING THE EASTERN SEABOARD... PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE LATEST MODEL GUIDANCE IS IN VERY GOOD AGREEMENT WITH THE MASS FIELD DETAILS OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS...SO A GENERAL MODEL BLEND WILL BE PREFERRED. ...PACIFIC FRONTAL SYSTEM CROSSING THE SOUTHERN CANADIAN ROCKIES...WITH 700 MB TOUGH/SURFACE REFLECTION THAT MOVES OUT OF ALBERTA/SASKATCHEWAN ACROSS NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY MON/TUES... PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MODELS REMAIN VERY GOOD AGREEMENT WITH THIS FEATURE...SO A GENERAL MODEL BLEND WILL AGAIN BE PREFERRED. ...WEAK PACIFIC WAVE ENTERING PACIFIC NORTHWEST LATE MON... ...ENERGY CROSSING THE NORTHERN ROCKIES TUES... ...DIGGING INTO THE CENTRAL/SOUTHERN PLAINS TUE NIGHT/WED... PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: AVERAGE A WEAK SHORTWAVE TOPS THE MEAN RIDGE IN THE EASTERN PACIFIC AND MOVES SOUTHEAST ACROSS THE PACIFIC NORTHWEST AND NORTHERN ROCKIES MON THROUGH TUES...THEN PROGRESSES INTO THE CENTRAL AND SOUTHERN PLAINS TUES NIGHT/WED. THERE IS STILL A DECENT AMOUNT OF SPREAD IN THE 00Z SUITE OF MODELS BY TUES NIGHT AND WED AS THE PATTERN AMPLIFIES AND THE SYSTEM DEVELOPS. THE GUIDANCE THOUGH IS STRONGLY SUPPORTING THE IDEA OF A CLOSED LOW DEVELOPING OVER THE GULF COAST STATES BY WED/THURS ALONG WITH A WELL-DEFINED AREA OF LOW PRESSURE THAT WILL BE GRADUALLY CROSSING THE LOWER MS/TN VALLEY REGION. THE 00Z NAM BECOMES GRADUALLY THE SLOWEST AND OVERALL THE DEEPEST SOLUTION. THE 12Z CMC IS BECOMES THE WEAKEST WITH ITS SURFACE LOW...WHILE THE 12Z UKMET BECOME THE STRONGEST. THE 00Z GFS AND 12Z ECMWF CLUSTER TOGETHER THE BEST AND HAVE A BETTER REPRESENTATION OF THE MODEL CONSENSUS. THE LATEST GEFS MEAN AND ECENS MEAN ARE JUST A LITTLE SOUTH OF THE GFS/ECMWF CLUSTER...BUT BASED ON THE LATEST DETERMINISTIC TRENDS...A BLEND OF THE GFS/ECMWF WILL SUFFICE FOR NOW. WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/ WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/ ORRISON