MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1251 PM EDT FRI AUG 26 2016 VALID AUG 26/1200 UTC THRU AUG 30/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION...INCLUDING PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ LOW AMPLITUDE SHORTWAVE CLIPPING NRN NEW ENGLAND TODAY/TONIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM. LOW-LEVEL SHORTWAVE LIFTING NEWD FROM THE PLAINS TONIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z NAM COMPROMISE CONFIDENCE: ABOVE AVERAGE OUTSIDE OF THE STRONGER NAM...THE MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM. UPPER TROUGH CROSSING THE N-CNTRL U.S. SAT...LIKELY REACHING NEW ENGLAND ON SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z NAM REMAINS A BIT SLOWER AND DEEPER WITH THIS SYSTEM WHILE THE 00Z CMC IS THE MOST PROGRESSIVE SOLUTION. THE 12Z GFS/00Z UKMET AND 00Z ECMWF ARE WELL CLUSTERED WITH THEIR SOLUTIONS IN BETWEEN...AND A CONSENSUS OF THESE SOLUTIONS WILL BE PREFERRED. UPPER TROUGH DROPPING SOUTH THROUGH BRITISH COLUMBIA ON SAT COLD FRONT MOVING THROUGH THE NRN PLAINS SUN NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF CONFIDENCE: AVERAGE THE 00Z CMC GRADUALLY BECOMES A MODESTLY DEEPER AND MORE PROGRESSIVE SOLUTION WITH THIS SYSTEM...WHEREAS THE 12Z NAM TENDS TO ALSO BE SOMEWHAT DEEPER THAN THE MODEL CONSENSUS BUT IS SLOWER THAN THE CONSENSUS. THE 12Z GFS/00Z UKMET AND 00Z ECMWF ALL CLUSTER TOGETHER IN BETWEEN THE NAM AND CMC CAMPS. WILL PREFER THE GFS/UKMET/ECMWF CLUSTER GIVEN THEIR AGREEMENT TO THE LATEST ENSEMBLE MEANS. UPPER TROUGH DIGGING SOUTH OFFSHORE BRITISH COLUMBIA BY MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 12Z NAM CONSENSUS CONFIDENCE: AVERAGE THE 12Z NAM IS QUICKER TO BRING THE UPPER TROUGH INTO THE PAC NW COAST COMPARED TO THE REMAINING DETERMINISTIC/ENSEMBLE GUIDANCE. THERE IS REASONABLE AGREEMENT IN THE REMAINING MODEL GUIDANCE. WEAK MID LEVEL TROUGH OVER THE SOUTHWEST THIS WEEKEND ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS/00Z ECMWF BLEND CONFIDENCE: AVERAGE WHILE THERE IS BROAD AGREEMENT WITH THE EVOLUTION OF THIS FEATURE...THE 12Z GFS/00Z ECMWF ARE IN THE MIDDLE OF THE LATEST SPREAD WITH BETTER AGREEMENT OVERALL COMPARED TO YESTERDAY. STILL...PREFER TO STAY CLOSER TO THE MIDDLE AND AWAY FROM THE EDGES/OUTLIERS IN THE GUIDANCE. LOW PRESSURE APPROACHING THE SOUTH FL AND THE KEYS BY SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 12Z GFS...00Z ECMWF MEAN CONFIDENCE: SLIGHTLY BELOW AVERAGE A BLEND OF THE STRONGER/NORTH 00Z ECMWF AND WEAKER/SOUTH 12Z GFS WORKS WELL HERE THROUGH EARLY SUN AS THE DIFFERENCES BETWEEN THE TWO MODELS ARE SMALL ENOUGH AND FIT THE LATEST SOUTHWARD TRENDS IN THE ENSEMBLE LOWS TO BE JUST SOUTH OF THE KEYS SUN MORNING. THE 00Z ECMWF DOES END UP A BIT CLOSER TO THE FL PENINSULA WITH THE LOW BY MON...WHICH IS A BIT TOWARD THE RIGHT SIDE OF THE LATEST ENSEMBLE LOW PLOTS. GIVEN THE DEVIATION IN THE 00Z ECMWF FROM THE REMAINING CONSENSUS IN POSITION...AND THE FACT THAT THE 00Z UKMET/CMC ARE STRONGER AND UNSUPPORTED AT THIS TIME BY ENOUGH OF THE REMAINING GUIDANCE...A 12Z GFS...00Z ECMWF MEAN BLEND IS PREFERRED. WEAK MID LEVEL LOW CENTER NEAR THE WESTERN GULF COAST ON SAT/SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF CONFIDENCE: SLIGHTLY BELOW AVERAGE THE 00Z UKMET/CMC ARE QUITE A BIT STRONGER WITH THIS FEATURE...AND WHILE ENSEMBLE TRENDS SHOW MORE SUPPORT FOR A STRONGER SYSTEM COMPARED TO YESTERDAY...THE LACK OF SUPPORT FOR THE 00Z UKMET/CMC BY THE LATEST NAM/GFS/ECMWF PRECLUDES THEM BEING INCLUDED IN THE PREFERENCE. WHILE THE NAM IS NOT OVERLY STRONG WITH THE FEATURE...IT DOES SHOW THE PRESENCE OF NUMEROUS SMALLER SCALE VORTICITY MAXIMA AROUND THE LOW CENTER WHICH IS NOT SUPPORTED IN THE REMAINING DETERMINISTIC GUIDANCE. THIS LEAVES A GFS/ECMWF BLEND WHICH IS REASONABLY CLOSE TO A CONSENSUS OF THE LATEST ENSEMBLE GUIDANCE. OTTO www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...