MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1154 AM EST MON MAR 02 2015 VALID MAR 02/1200 UTC THRU MAR 06/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. INITIAL UPPER LOW/TROUGH OVER CALIFORNIA REACHING THE CNTRL ROCKIES MON NIGHT ASSOCIATED SFC LOW / COLD FRONT MOVING OUT INTO THE CNTRL PLAINS TUE MORNING AND THROUGH THE DAY ON TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS...00Z ECMWF BLEND CONFIDENCE: AVERAGE TIMING DIFFERENCES WITH THE REMNANT SHORTWAVE AS IT REACHES THE CNTRL PLAINS EARLY TUE ALONG WITH THE ASSOCIATED COLD FRONT EXTENDING WWD ACROSS THE ROCKIES HAVE CLOSED UP A BIT FROM THE 00Z RUNS...BUT THEY STILL REMAIN. THE 12Z NAM AND 00Z CMC REMAIN SLIGHTLY SLOWER WITH THE SHORTWAVE COMPARED TO THE AGREEABLE 12Z GFS AND 00Z ECMWF. WHILE THERE WAS SOME DISAGREEMENT BETWEEN THE MODELS AND THEIR RESPECTIVE ENSEMBLES...THE AGREEMENT BETWEEN THE GFS/ECMWF AGREE PRETTY WELL WITH THEIR ENSEMBLE MEANS. BEYOND TUE...AN UPPER TROUGH MOVING ACROSS THE NRN PLAINS TAKES OVER AND IMPACTS A COLD FRONT REACHING THE SOUTHEAST...DISCUSSED IN THE NEXT SECTION. UPPER TROUGH AXIS DROPPING OUT OF CANADA INTO THE N-CNTRL U.S. TUE EVENTUAL STRONG COLD FRONT REACHING THE SOUTHEAST THU MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z ECMWF CONFIDENCE: A LITTLE BELOW AVERAGE THE 12Z NAM ACCELERATED THE AMPLIFYING WAVE AND ASSOCIATED SURFACE FEATURES THAT FORMS OVER THE CNTRL PLAINS WED AND THE ASSOCIATED SURFACE COLD...ALTHOUGH THE 12Z GFS WAS STILL FASTER THAN THE NAME. THE SREF/GEFS/EC MEANS SUGGEST THAT THE GFS IS TOO WEAK WITH A SOUTHEAST UPPER RIDGE WHICH ALLOWS THE COLD FRONT TO MORE QUICKLY PROGRESS SOUTH AND EAST WHILE THE 02/00Z ECMWF HAS REMAINED FAIRLY STEADY IN THE TREATMENT OF THE WAVE AND SURFACE FEATURES. THUS WILL CONTINUE TO SUGGEST A SOLN CLOSE TO THE 02/00Z ECMWF ALTHOUGH KEEPING IN MIND THAT THE CURRENT ENSEMBLE MEANS SUPPORT A FASTER SOLUTION THAN THE SLOWER NAM/UKMET BUT ENSEMBLE SPREAD REMAINS LARGE WHICH LOWERS CONFIDENCE. SECONDARY SHORTWAVE ENERGY DIVING SOUTH OFF CALIFORNIA TODAY CROSSING BACK INTO SOUTHWEST STATES LATE TUESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z GFS / 00Z ECMWF BLEND CONFIDENCE: A LITTLE BELOW AVERAGE THE MODELS SHOW REASONABLY CLOSE AGREEMENT HERE AFTER TRENDING TOWARD A COMMON MIDDLE GROUND...BUT WITH THE REMAINING SPREAD...PREFER TO STAY TOWARD THE MIDDLE. THIS IS BEST REPRESENTED BY THE 12Z GFS AND 00Z ECMWF...BOTH MODELS SHOWING ONLY MINOR RUN TO RUN CHANGES SINCE THEIR 00Z RUNS YESTERDAY. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... BANN