MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1226 PM EDT THU AUG 07 2014 VALID AUG 07/1200 UTC THRU AUG 11/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...STRONG UPPER TROUGH CROSSING NEW ENGLAND/CANADIAN MARITIMES THROUGH SAT... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE A LARGE UPPER TROUGH OVER THE NORTHEAST ATTM WILL MOVE GRADUALLY EWD AND THEN NEWD OVER THE NEXT COUPLE OF DAYS THROUGH THE CANADIAN MARITIMES. THERE WILL BE SOME ADDITIONAL AMPLIFICATION OF THE HEIGHT FALLS AND THERE WILL BE A CLOSED UPR LOW CENTER THAT SHOULD TRAVERSE NOVA SCOTIA AND SRN NEWFOUNDLAND THROUGH SAT. GIVEN REASONABLE AGREEMENT ON THE LARGER SCALE...WILL PREFER A GENERAL MODEL COMPROMISE TO RESOLVE THE SMALLER SCALE DIFFS. ...SLOW-MOVING CONVECTIVE VORT TRACKING FROM THE MID MS VALLEY TO THE OH/TN VALLEYS... ...SURFACE LOW AND FRONTAL ZONE IMPACTING THE OH/TN VALLEYS TO THE MID-ATLANTIC... PREFERENCE: BLEND OF THE 00Z ECMWF AND 00Z UKMET CONFIDENCE: AVERAGE A WELL-DEFINED CONVECTIVE VORT OVER CNTRL MO THIS MORNING COUPLED WITH A SFC LOW ALONG A W/E ORIENTED FRONTAL ZONE WILL TRACK GRADUALLY EASTWARD OVER THE NEXT 3 DAYS AND MOVE INTO THE OH/TN VLYS FRI AND SAT. LOW PRESSURE IS THEN EXPECTED TO REDEVELOP OVER THE SRN MID-ATLANTIC REGION ON SUN. THE 12Z NAM AND 12Z GFS AGAIN APPEAR TO BE A LITTLE SLOWER THAN THE 00Z ECMWF/00Z UKMET AND 00Z GEM SOLNS WITH THE SFC LOW EVOLUTION. BY SAT AND SUN...THE NAM AND GFS ARE ALSO A LITTLE FARTHER NORTH WITH THEIR RESPECTIVE FRONTAL ZONES OVER THE OH VLY AND THE MID-ATLANTIC REGION. ALL OF THE MODELS ARE ACTUALLY SUPPORTING A BONA FIDE HVY RAINFALL THREAT TO THE OH/TN VLYS AND MID-ATLANTIC REGION...BUT WITH THE REMNANT CONVECTIVE VORT ENERGY AND FRONTAL ZONE ON THE NAM AND GFS TENDING TO LINGER NORTH OF THE NON-NCEP SOLNS...THE QPF ON THE NAM AND GFS ARE ALSO CONCENTRATED A LITTLE FARTHER NORTH. THE LATEST ECENS MEAN FAVORS THE NON-NCEP CAMP...WITH THE GEFS MEAN FAVORING THE NAM/GFS CAMP. WILL FAVOR A BLEND OF THE 00Z ECMWF/00Z UKMET IN KEEPING WITH CONTINUITY. ...SMALL CLOSED LOW/TROUGH OVER THE INTERMOUNTAIN WEST EJECTING INTO THE PLAINS... PREFERENCE: BLEND OF THE 00Z ECMWF/00Z UKMET AND 00Z GEM CONFIDENCE: AVERAGE A SMALL CLOSED LOW OVER NRN UT THIS MORNING WILL FINALLY BE SHIFTING EAST OVER THE NEXT DAY OR SO AND SHOULD EJECT OUT INTO THE N CNTRL PLAINS REGION THROUGH FRI AND SAT. ON SUN...THIS ENERGY WILL SHEAR OUT ACROSS THE MIDWEST. THE 12Z NAM AND 12Z GFS ARE BOTH A BIT STRONGER THAN THE 00Z ECMWF/00Z UKMET AND THE 00Z GEM WITH THE ENERGY AS IT CROSSES THROUGH THE PLAINS. IN THE CASE OF THE GFS...THERE IS SOME EVIDENCE OF CONVECTIVE FEEDBACK. WILL PREFER TO LEAN TWD THE NON-NCEP SOLNS. ...CLOSED LOW DEVELOPING ALONG THE CA COASTLINE... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: ABOVE AVERAGE ALL OF THE MODELS SHOW GOOD AGREEMENT IN ALLOWING SRN STREAM SHORTWAVE ENERGY TO BREAK AWAY AND AMPLIFY INTO A CLOSED LOW CENTER BY SAT AND SUN NEAR THE COAST OF CNTRL CA. THE 00Z UKMET IS A TAD WEAKER THAN THE MULTI-MODEL CONSENSUS...WITH THE REMAINING MODELS WELL CLUSTERED. WILL FAVOR A NON-UKMET CONSENSUS. ...SHORTWAVE TROUGH AFFECTING THE PACIFIC NORTHWEST BY EARLY SATURDAY... PREFERENCE: BLEND OF THE 00Z ECMWF AND 00Z GEM CONFIDENCE: AVERAGE A PROGRESSIVE SHORTWAVE TROUGH CROSSING THE PAC NORTHWEST ON FRI WILL TRAVERSE SRN CANADA THROUGH THE REMAINDER OF THE WEEKEND. ALL OF THE MODELS ARE IN VERY GOOD MASS FIELD AGREEMENT THROUGH FRI WITH THE DETAILS OF THE TROUGH. HOWEVER...BY SAT AND SUN THE 12Z NAM AND 12Z GFS TEND TO LAG THE GLOBAL MODEL CONSENSUS...WITH THE 00Z ECMWF/00Z UKMET AND 00Z ECMWF ALL A BIT MORE PROGRESSIVE. THE 00Z UKMET WAS THE MOST PROGRESSIVE. WILL FAVOR A BLEND OF THE 00Z ECMWF AND 00Z GEM ATTM BASED ON THEIR STRONGER MODEL CLUSTERING. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON