MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1245 AM EDT WED JUL 06 2016 VALID JUL 06/0000 UTC THRU JUL 09/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ EASTERN PACIFIC UPPER LOW AND SHORTWAVES MOVING INTO THE NORTHWEST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MODELS REMAIN IN GENERAL GOOD AGREEMENT ON THE EVOLUTION OF THIS UPPER LOW...WITH ONLY MINOR TIMING AND PLACEMENT DIFFERENCES. THUS A GENERAL MODEL MODEL BLEND SHOULD SUFFICE ACROSS THE NORTHWEST THROUGH THE SHORT TERM. SHORTWAVE MOVING EAST FROM MONTANA THIS MORNING...REACHING THE NRN PLAINS THU AND GREAT LAKES FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z CMC CONSENSUS CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z CMC IS A SLOWER OUTLIER IN THE LATEST DETERMINISTIC/ENSEMBLE GUIDANCE. BY FRI NIGHT ACROSS THE GREAT LAKES...THE 00Z GFS IS TOWARD THE FASTER EDGE OF THE SPREAD WHILE THE 12Z ECMWF IS TOWARD THE SLOWER EDGE OF THE ENSEMBLE SPREAD. THERE ARE RELATIVELY MINOR STRENGTH AND TIMING DIFFERENCES IN THE REMAINING GUIDANCE...BUT NO CLEAR SOLUTION STANDS OUT AS PREFERABLE ONCE EXCLUDING THE 12Z CMC. NORTHERN STREAM SHORTWAVE ENERGY ACROSS CANADA INTO NORTHERN NEW ENGLAND WED/THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/ECMWF CONSENSUS CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MAIN SENSIBLE WEATHER IMPACT FROM THIS SYSTEM COMES ON THURSDAY AS A SURFACE LOW IS EXPECTED TO MOVE INTO NEW ENGLAND. IN GENERAL A CONSENSUS OF THE 00Z GFS AND THE 12Z ECMWF APPEARS TO RESULT IN A GOOD CONSENSUS APPROACH WHILE THE 00Z NAM TRACKS THE LOW FARTHER SOUTH GIVEN DIFFERENT HANDLING OF THE UPSTREAM VORTICITY MAX. THE 12Z UKMET/CMC REMAIN CLUSTERED ON EITHER SIDE OF THE GFS/ECMWF POSITION. SHORTWAVE IMPULSES MOVING INTO THE WEAK MID ATLANTIC TROUGH ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/12Z ECMWF CONSENSUS CONFIDENCE: SLIGHTLY ABOVE AVERAGE WEAK SHORTWAVE IMPULSES ARE FORECAST EACH DAY TO RIDE EAST IN THE ZONAL FLOW INTO THE WEAK TROUGHING SITUATED OVER THE MID ATLANTIC. THE LIKELIHOOD OF ORGANIZED CONVECTIVE SYSTEMS AND THEIR RELATED VORTICITY MAXIMA MAKE FOR A CHALLENGING FORECAST EVOLUTION WITH DIFFICULT TO TRACK FEATURES. PLEASE SEE THE QPFPFD FOR QPF DETAILS...BUT FOR THE PURPOSE OF THIS DISCUSSION...AND 00Z GFS/12Z ECMWF BLEND WILL BE PREFERRED FOR THE SAKE OF CONTINUITY. IT IS CLEAR THAT THE 12Z UKMET IS ON THE FASTER EDGE OF THE LATEST GUIDANCE AND IS LEAST LIKELY TO VERIFY. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO