MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1242 AM EDT FRI SEP 11 2015 VALID SEP 11/0000 UTC THRU SEP 14/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE TROUGH INFLUENCING CALIFORNIA/SOUTHWEST THIS WEEKEND... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS DEPICT A SIMILAR LARGE-SCALE EVOLUTION OF THIS SYSTEM AS THE TROUGH NEARS THE CA COAST THROUGH SAT. HOWEVER...BY SUN THE SYSTEM WILL BEGIN TO MOVE EAST AND INLAND. THE 12Z CMC IS THE FASTEST TO EJECT THE SYSTEM INLAND TOWARD THE SOUTHERN GREAT BASIN. THE REMAINING MODELS ARE CLUSTERED A TAD SLOWER. THE 12Z UKMET OVERALL APPEARS A BIT TOO WEAK COMPARED TO THE GLOBAL MODEL CONSENSUS. STRONGER MODEL CLUSTERING FAVORS THE 00Z GFS AND 12Z ECMWF...AND THUS A BLEND OF THESE SOLUTIONS WILL BE PREFERRED. ...SURFACE LOW LIFTING OFF NEW ENGLAND THROUGH FRI... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: ABOVE AVERAGE THE MODELS ARE GENERALLY IN GOOD AGREEMENT LIFTING THE SURFACE LOW NEAR THE DELMARVA NORTHEAST AND UP OFF THE NEW ENGLAND COAST ON FRI. GRADUALLY THE 12Z UKMET AND 12Z CMC LAG THE 00Z GFS/00Z NAM AND 12Z ECMWF WITH RESPECT TO TIMING. THE LATEST GEFS MEAN AND ECENS MEAN FAVOR THE SLIGHTLY FASTER CONSENSUS...AND VERY STRONGLY SUPPORT A BLEND OF THE GFS AND ECMWF. ...CLOSED LOW SETTING UP OVER THE OHIO VALLEY BY SAT EVENING... ...LOW PRESSURE DEVELOPING OVER THE MID-ATLANTIC REGION... PREFERENCE: BLEND OF THE 12Z ECMWF AND 12Z ECENS MEAN CONFIDENCE: BELOW AVERAGE ALL OF THE MODELS SHOW SHORTWAVE ENERGY DIGGING SOUTHEAST THROUGH THE MIDWEST AND AMPLIFYING INTO A CLOSED UPPER LOW ACROSS THE OH VALLEY SAT AND SUN BEFORE THEN PIVOTING ACROSS THE CENTRAL APPALACHIANS AND NORTHEAST BY MON. MEANWHILE...THE HEIGHT FALLS WILL BE DEVELOPING SURFACE LOW PRESSURE OVER THE MID-ATLANTIC REGION IN THE IMMEDIATE LEE OF THE CENTRAL APPALACHIANS WHICH IS FORECAST TO LIFT NORTH INTO NEW ENGLAND. THE 00Z NAM AND 00Z GFS ARE THE FASTEST SOLUTIONS TO PIVOT THEIR HEIGHT FALLS INTO THE NORTHEAST AND AS A RESULT ARE FASTER TO LIFT LOW PRESSURE OUT OF THE MID-ATLANTIC AND ACROSS NEW ENGLAND. THE 12Z UKMET IS THE SLOWEST...FOLLOWED CLOSELY BY THE 12Z ECMWF. THE 12Z CMC SPLITS THE DIFFERENCE BETWEEN FASTER AND SLOWER CAMPS...AND IS A LITTLE FASTER THAN THE 12Z ECMWF. THE LATEST ECENS MEAN FAVORS THE SLOWER ECMWF/UKMET CAMP...WITH THE GEFS MEAN A LITTLE SLOWER THAN THE GFS/NAM CAMP. CONFIDENCE IS LIMITED...BUT IT APPEARS THE NAM AND ESPECIALLY THE GFS ARE PUTTING TO MUCH VORT ENERGY TOO FAR NORTH WITHIN THE OVERALL TROUGH AXIS. THE GFS IS SHOWING SOME CLEAR EVIDENCE OF CONVECTIVE FEEDBACK AFTER 36 HOURS AND THUS WILL BE DISMISSED. WILL PREFER THE SLOWER NON-NCEP SOLUTION IDEA OF MORE ENERGY FARTHER SOUTH AND FOCUSED MORE IN THE BASE OF THE TROUGH. ALTHOUGH THE UKMET LIKELY HAS TOO MUCH ENERGY TOO FAR SOUTH. WILL PREFER A BLEND OF 12Z ECMWF AND 12Z ECENS MEAN AT THIS POINT. ...SHORTWAVE DROPPING SOUTHEAST TOWARD THE NORTHWEST BY MON... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS AGREE IN TAKING A SHORTWAVE SOUTHEAST THROUGH BRITISH COLUMBIA AND TOWARD THE NORTHWEST BY MON. THE 12Z UKMET IS A TAD SHARPER THAN THE GLOBAL MODEL CONSENSUS. THE 00Z NAM AND 12Z CMC ARE ALSO SEEN AS BEING PERHAPS A TAD TOO SLOW. WILL PREFER THE STRONGLY CLUSTERED 00Z GFS AND 12Z ECMWF AT THIS POINT WHICH ARE A TAD FASTER BY COMPARISON. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON