MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1158 PM EDT TUE MAY 13 2014 VALID MAY 14/0000 UTC THRU MAY 17/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...NEGATIVELY TILTING LONGWAVE TROUGH/CLOSED LOW OVER THE CENTRAL/EASTERN U.S... ...LOW PRESSURE LIFTING FROM THE LOWER MS VALLEY THROUGH THE GREAT LAKES... PREFERENCE: BLEND OF THE 12Z ECMWF/12Z UKMET CONFIDENCE: AVERAGE THE MODELS CONTINUE TO SUPPORT ADDITIONAL SHORTWAVE ENERGY DIGGING SEWD THROUGH THE SRN PLAINS AND INTO THE LWR MS VLY THROUGH WED. THE GUIDANCE SUPPORTS SFC CYCLOGENESIS INITIATING IN RESPONSE TO THE NEW HEIGHT FALLS ALONG A FRONTAL ZONE SITUATED OVER THE LWR MS/TN VLYS...WITH LOW PRESSURE THEN PROGGED TO LIFT NEWD THURS INTO THE OH VLY AND THROUGH THE GRT LAKES REGION ON FRI. ALL OF THE MODELS SHOW SOME ADDITIONAL INTRUSION OF NRN STREAM SHORTWAVE ENERGY ON THURS AND FRI WHICH SHOULD ALLOW FOR A DEEP CLOSED LOW TO SET UP OVER THE UPR MIDWEST AND A SEWD EXTENDING TROUGH AXIS THAT GOES NEG-TILT THROUGH EARLY SAT ACROSS THE EAST. THE NAM IS A MODESTLY SLOWER AND DEEPER SOLN ALOFT COMPARED TO THE GLOBAL MODEL CONSENSUS. THE GFS IS ALSO A TAD SLOWER JUST LIKE THE NAM BUT NOT QUITE AS DEEP ALOFT. THE ECMWF/UKMET AND GEM SHOW COMPARABLE DEPTH ALOFT...WITH THE GEM JUST A TAD ON THE DEEP SIDE...BUT THESE MODELS CLUSTER VERY WELL WITH TIMING AND SUPPORT A MODESTLY FASTER SOLN WITH THE EJECTING SFC LOW AND ASSOCD FRONTAL ZONE. BASED ON THE LATEST MODEL TRENDS AND CLUSTERING...WILL FAVOR A BLEND OF THE ECMWF AND UKMET...WHICH ALSO SUPPORTED BY THE LATEST ECENS MEAN. ...WEAK SHORTWAVE TROUGH/SURFACE LOW IMPACTING THE PACIFIC NORTHWEST THURS NIGHT/FRI... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE ALL OF THE MODELS SHOW A WEAK SHORTWAVE TROUGH EJECTING OUT OF THE BASE OF A LARGER SCALE TROUGH AND CLOSED LOW OVER THE EASTERN PAC OCEAN SOUTH OF THE GULF OF AK AND ATTEMPTING TO ENTER THE PAC NORTHWEST THURS NIGHT AND FRI. A WEAK AREA OF LOW PRESSURE IS EXPECTED TO BE ASSOCD WITH THIS SYS. OVERALL THE BEST MODEL CLUSTERING SFC AND ALOFT SUPPORTS A BLEND OF THE GFS AND ECMWF. ...UPPER LOW APPROACHING THE PAC NORTHWEST BY SAT... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW AN UPR LOW APPROACHING THE PAC NORTHWEST BY SAT WITH THE BULK OF THE HEIGHT FALLS FORECAST TO REMAIN OFFSHORE THROUGH THE SHORT RANGE PERIOD. WILL FAVOR A GENERAL MODEL COMPROMISE ATTM WITH THIS NEXT SYS TO RESOLVE THE SMALLER SCALE DIFFS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON