MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 244 AM EDT TUE MAY 17 2016 VALID MAY 17/0000 UTC THRU MAY 20/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...SHORTWAVE CROSSING THE GREAT LAKES/NORTHEAST THROUGH WED/THURS... PREFERENCE: BLEND OF THE 00Z ECMWF/12Z ECENS MEAN AND 00Z GEFS MEAN CONFIDENCE: SLIGHTLY BELOW AVERAGE A NORTHERN STREAM SHORTWAVE TROUGH OVER THE WESTERN LAKES WILL DROP SOUTHEAST AND SHEAR INTO AN ELONGATED AXIS OF TROUGHING ACROSS THE LOWER GREAT LAKES/UPPER OH VALLEY AND INTO THE NORTHEAST THROUGH WED AND THURS. THE 00Z NAM IS THE MOST PROGRESSIVE SOLUTION...FOLLOWED CLOSELY BY THE 00Z GFS AND 00Z UKMET. THE 00Z CMC AND 00Z ECMWF ARE BOTH SLOWER...AND THE 00Z ECMWF ALSO IS A BIT DEEPER. THE LATEST GEFS MEAN AND ECENS MEAN THOUGH ACTUALLY SUPPORT THE RELATIVELY SLOWER/STRONGER ECMWF. WILL LEAN TOWARD A BLEND OF THE ECMWF AND THE GEFS/ECENS MEANS AT THIS POINT BASED ON THEIR STRONGER MODEL CLUSTERING. CONFIDENCE THOUGH REMAINS SOMEWHAT LIMITED GIVEN THE DETERMINISTIC MODEL SPREAD. ...SHORTWAVE IMPULSE CURRENTLY CROSSING THE GULF COAST STATES... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE A SHORTWAVE TROUGH NOW OVER THE CENTRAL GULF COAST STATES WILL SHEAR OUT ON TUES ACROSS THE SOUTHEAST. THE MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE MASS FIELD DETAILS OF THIS SYSTEM...SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED. ...CLOSED LOW DIGGING INTO THE SOUTHWEST ON TUES... ...EJECTING OUT INTO THE CENTRAL PLAINS BY THURS... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS CONTINUE GOOD AGREEMENT AND CONTINUITY WITH THE CLOSED LOW DIGGING ACROSS THE WEST INTO THE SOUTHWEST ON TUES. THE ENERGY WILL THEN EJECT EAST OUT TOWARD THE CENTRAL PLAINS BY THURS. THERE IS NOT MUCH MODEL SPREAD...ALTHOUGH THE 00Z ECMWF MAY BE A TAD TOO STRONG WITH THE HEIGHT FALLS EJECTING OUT OVER THE CENTRAL PLAINS BY THE END OF THE PERIOD. AT THIS POINT THERE IS SUFFICIENT MASS FIELD AGREEMENT TO GO WITH A GENERAL MODEL COMPROMISE. ...SURFACE WAVE/FRONTAL ZONE IMPACTING THE SOUTHERN PLAINS/LOWER MS VALLEY... PREFERENCE: BLEND OF THE 00Z GFS/00Z UKMET AND 00Z ECMWF CONFIDENCE: AVERAGE A SUBTLE SHORTWAVE AND ASSOCIATED JET STREAK ARE DEPICTED IN WV IMAGERY EJECTING OUT INTO THE CENTRAL/SOUTHERN HIGH PLAINS JUST EAST OF THE FOUR CORNERS REGION WHICH WILL FOCUS A WAVE OF LOW PRESSURE DOWN INTO WESTERN TX ON TUES. MEANWHILE A FRONTAL ZONE WILL BE DRAPED TO THE EAST ACROSS TX AND ALONG THE GULF COAST STATES. WEAK WAVE ACTIVITY SHOULD TRAVERSE THE BOUNDARY THROUGH WED AND BY WED NIGHT/THURS THERE WILL BE A WAVE EXITING OFF THE SOUTHEAST COAST. MOST OF THE MODELS DEPICT A SIMILAR SOLUTION WITH THE EVOLUTION OF THE FRONTAL ZONE AND ASSOCIATED WAVE ACTIVITY...ALTHOUGH BY WED AND THURS THE 00Z NAM APPEARS TO BE A LITTLE TOO FAR NORTH WITH ITS FRONTAL ZONE INVOLVING THE SOUTHEAST. THE 00Z CMC ALSO IS OUT OF TOLERANCE WITH THE REMAINING GUIDANCE CONCERNING THE INITIAL EVOLUTION OF LOW PRESSURE OVER THE SOUTHERN HIGH PLAINS FOR TUES...AND BY TUES NIGHT AND WED APPEARS TO BE A LITTLE TOO STRONG WITH ITS WAVE FEATURE NEAR THE CENTRAL GULF COAST. WILL PREFER A CONSENSUS OF THE BETTER CLUSTERED 00Z GFS/00Z UKMET AND 00Z ECMWF AT THIS TIME. ...SHORTWAVE ENERGY SKIRTING THE NORTHERN PLAINS WED/THURS... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE GUIDANCE INDICATES SOME SHORTWAVE ENERGY/TROUGHING CROSSING THE SOUTHERN PRAIRIES OF CANADA AND CLIPPING FAR NORTHERN ND/MN AS THIS WAVE WASHES OUT. THERE IS SOME MODEST SPREAD WITH TIMING AND DEPTH...BUT AT THIS POINT A GENERAL MODEL COMPROMISE WILL SUFFICE TO RESOLVE THESE MINOR DIFFERENCES. ...UPPER LOW DIGGING INTO THE NORTHWEST BY WED/THURS... PREFERENCE: BLEND OF THE 00Z NAM/00Z GFS AND 00Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MODELS CONTINUE TO SHOW STRONG AGREEMENT OVERALL WITH THE CLOSED LOW PARALLELING THE BC COAST WITH JET/SHORTWAVE ENERGY UNDERCUTTING IT WED INTO THURS SUPPORTING GOOD HEIGHT FALLS OVER THE PACIFIC NORTHWEST. THE 00Z UKMET AND 00Z CMC BOTH APPEAR TO BE FOCUSING ENERGY A BIT FARTHER WEST ALONG THE IMMEDIATE COAST COMPARED TO THE MODEL CONSENSUS. THE 00Z NAM/00Z GFS AND 00Z ECMWF FOCUS THE CORE OF THE HEIGHT FALLS JUST A LITTLE FARTHER INLAND WHICH IS MORE STRONGLY SUPPORTED BY THE LATEST GEFS/ECENS MEANS. WILL THEREFORE PREFER THE NAM/GFS/ECMWF CLUSTER AT THIS POINT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON