MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 244 PM EDT SUN JUL 20 2014 VALID JUL 20/1200 UTC THRU JUL 24/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES SHORTWAVE TROUGH LIFTING THROUGH THE NORTHEAST WEAK MID-LEVEL DISTURBANCE LEFT BEHIND OVER THE SOUTHEAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE UP TIL 00Z/23 12Z GFS/ECMWF/UKMET COMPROMISE AFTER 00Z/23 CONFIDENCE: ABOVE AVERAGE THE GUIDANCE IS IN GOOD AGREEMENT WITH THE NRN PORTION OF THIS SYSTEM LIFTING THROUGH THE NORTHEAST. THE MODELS ALSO GENERALLY AGREE WITH THE WEAKLY DEFINED SRN PORTION OVER THE GULF COAST REGION THROUGH ABOUT 00Z/23. IT IS AT THIS POINT THAT THE NAM DIVERTS FROM THE CONSENSUS AND DEVELOPS THE REMNANT UPPER LOW MORE SWWD. THE 00Z CMC ENDS UP FASTER THAN THE REMAINING MODEL CONSENSUS AFTER 00Z/23 OVER THE SOUTHEAST BUT GOOD AGREEMENT/CONTINUITY EXISTS WITH THE GFS/ECMWF/UKMET AND THE ENSEMBLE MEANS. UPPER TROUGH/COLD FRONT CLIPPING THE NORTHERN U.S TODAY AND MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS ARE IN GOOD AGREEMENT AT LEAST ON THE LARGER SCALE WITH THIS SYSTEM...SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED TO RESOLVE THE SMALLER SCALE DIFFS. DEEP UPPER TROUGH/CLOSED LOW DEVELOPING OVER THE GULF OF AK AND IMPACTING THE NORTHWEST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS/ECMWF/CMC COMPROMISE CONFIDENCE: SLIGHTLY ABOVE AVERAGE DESPITE SMALL ADJUSTMENTS IN THE MODELS OVER THE PAST 24 HOURS...THERE REMAINS PRETTY GOOD AGREEMENT WITH AN APPROACHING...STRONG...CLOSED LOW THROUGH TUE MORNING. FROM TUE MORNING THROUGH WED EVENING HOWEVER...SOME NOTABLE DIFFERENCES ARE SEEN WITH A FASTER UPPER TROUGH PROGRESSION IN THE 12Z NAM/UKMET COMPARED TO THE REMAINING MODEL CONSENSUS. THE GFS/ECWMF REMAIN RATHER CONSISTENT FROM RUN TO RUN AND HAVE BETTER AGREEMENT FROM THE ENSEMBLE MEANS COMPARED TO THE NAM/UKMET. THE 12Z CMC HAS MADE MINOR ADJUSTMENTS TOWARD THE GFS/ECMWF...ENOUGH TO INCLUDE IT IN THE PREFERENCE. THEREFORE...A BLEND OF THE GFS/ECMWF/CMC IS RECOMMENDED. WEAK MID/UPPER LEVEL LOW LIFTING NORTH THROUGH CA THROUGH SUN SURFACE LOW DEVELOPING FROM THE NRN PLAINS BY MON AND TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS...00Z ECMWF COMPROMISE CONFIDENCE: AVERAGE THERE HAS BEEN A SLIGHT TREND IN MOST OF THE GUIDANCE SINCE YESTERDAY TO BE QUICKER WITH REMNANT SHORTWAVE ENERGY THAT IS EXPECTED TO TRACK FROM THE WEST TODAY...AROUND A SUBTROPICAL RIDGE CENTERED OVER NEW MEXICO...INTO THE N-CNTRL U.S. LATE ON MON. THE UKMET/CMC STILL APPEAR TO BE A BIT TOO FAST/NORTHEAST WITH THE LOW LEVEL LOW ACROSS THE DAKOTAS INTO MINNESOTA. EARLY TUE...THE 12Z NAM DOES GET A BIT FASTER WITH THE LOW THROUGH MINNESOTA ON TUE BUT OTHERWISE APPEARS USABLE. THE GFS/ECMWF COMBO FIT THE PATTERN BEST THROUGH 00Z/24...WED EVENING...WITH THE PROGRESSIVE COLD FRONT ACROSS THE MISSISSIPPI VALLEY. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO