MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 236 AM EDT WED APR 08 2015 VALID APR 08/0000 UTC THRU APR 11/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SURFACE LOW OVER THE MID MS VALLEY THROUGH EARLY WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE ONLY MINOR TIMING DIFFERENCES REMAIN WITH THIS LOW BEFORE DISSIPATING LATER TODAY. A GENERAL MODEL COMPROMISE IS PREFERRED TO SMOOTH OUT LINGERING DETAIL DIFFERENCES. WRN UPPER TROUGH AXIS REACHING THE CNTRL PLAINS THU MORNING ACCOMPANYING SURFACE LOW TRACKING INTO THE GREAT LAKES THU NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z NAM/GFS/UKMET CONFIDENCE: AVERAGE SOME WEAKER TRENDS HAVE BEEN NOTED IN THE DETERMINISTIC/ENSEMBLE GUIDANCE REGARDING THE SHORTWAVE AS IT REACHES THE CNTRL PLAINS EARLY THU COMPARED TO 24 HOURS AGO...BUT THE 00Z ECMWF CONTINUES TO BE WEAKEST AND UNSUPPORTED BY THE LATEST 500 MB ENSEMBLE SPAGHETTI HEIGHTS. INTO FRI AND SAT...THE 00Z NAM/GFS ARE TOWARD THE FASTER EDGE OF THE ENSEMBLE SPREAD...WITH THE 00Z UKMET TOWARD THE MIDDLE TO SLOWER SIDE OF THE SPREAD. IN TERNS OF INTENSITY...THE NAM/GFS/UKMET ARE SIMILAR...BUT A BLEND OF THEIR TIMING DIFFERENCES IS PREFERRED...WITH THOUGHTS THAT THE 00Z CMC IS TOO SLOW AND THE 00Z ECMWF A BIT TOO WEAK. MID LEVEL SHORTWAVE TROUGH DROPPING INTO THE N-CNTRL U.S. FROM CANADA THU-FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 00Z CMC BLEND CONFIDENCE: AVERAGE THE MODELS CONTINUE TO STRUGGLE WITH THE DEGREE OF SHORTWAVE ENERGY THAT DROPS DOWN INTO THE NORTHERN U.S. THU NIGHT AND FRI BUT BETTER RUN TO RUN CONTINUITY EXISTS TONIGHT COMPARED TO MON NIGHT. THE 00Z ECMWF HAS TRENDED IN THE DIRECTION OF THE REMAINING MODEL CONSENSUS BUT THE 00Z CMC REMAINS A BIT MORE AGGRESSIVE IN THE SHORTWAVE DROPPING SOUTH AND TOWARD THE WESTERN EXTREME OF THE LATEST DETERMINISTIC/ENSEMBLE SPREAD. A NON 00Z CMC MODEL CONSENSUS MAKES UP AN AGREEABLE COMPROMISE IN THE MIDDLE...CLOSEST TO THE LATEST SREF/GEFS/EC ENSEMBLE MEANS. CONFIDENCE HAS INCREASED WITH THIS FEATURE GIVEN BETTER MODEL AGREEMENT AND BETTER RUN TO RUN MODEL CONSISTENCY. SURFACE WAVE EXITING OFF THE MID-ATLANTIC COAST TODAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON 00Z CMC BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 12Z CMC IS A BIT CLOSER TO THE COAST WITH THE SURFACE LOW PLACEMENT...AWAY FROM THE REMAINING DETERMINISTIC AND ENSEMBLE MEAN CONSENSUS. A NON 00Z CMC BLEND OF GUIDANCE SHOWS GOOD AGREEMENT AND FORMS A GOOD COMPROMISE. *SHORTWAVE TROUGH APPROACHING THE NORTHWEST ON FRI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW RELATIVELY MINOR DIFFERENCES WITH A TROUGH APPROACHING THE PACIFIC NORTHWEST BY FRI SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED AT THIS TIME. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO