MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 144 AM EST WED FEB 12 2014 VALID FEB 12/0000 UTC THRU FEB 15/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION AND FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. EASTERN U.S. CYCLONE AND WINTER STORM ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z GFS / 00Z ECMWF / 21Z SREF MEAN CONFIDENCE: AVERAGE ON THE LARGE SCALE...BELOW AVERAGE FOR PRECIPITATION TYPE RELATIVELY SMALL DIFFERENCES STILL EXIST BETWEEN THE LATEST AVAILABLE GUIDANCE ON THE SYNOPTIC SCALE...BUT THESE DIFFERENCES TRANSLATE TO LARGE IMPACTS AT THE SURFACE WITH P-TYPE. ONE CONSISTENT TREND HAS BEEN SLOWER FROM LAST NIGHTS MODEL RUNS...BUT THERE HAS BEEN MORE OF A WOBBLE OCCURRING BETWEEN EAST/WEST DISPLACEMENT WITH THE UPPER TROUGH / CORRESPONDING SURFACE LOW WITH EACH MODEL RUN. THE 00Z NAM IS STILL ON THE WEAKER SIDE OF THE GUIDANCE WITH THE AMPLIFYING UPPER TROUGH INTO THE SOUTHEAST EARLY THU AND NEVER REALLY CLOSES OFF A CENTER AT 500 MB...WHICH IS A SIGNIFICANT DEPARTURE FROM THE REMAINING MODELS. THE NAM THEREFORE HAS A DIFFERING 850 MB LOW ORIENTATION AND IS FASTER/WEAKER AT THE SURFACE. THE 00Z GFS POSITION LOOKS FINE...JUST A BIT EAST OF THE 12Z ECMWF BUT IS WEAKER AT 850-500 MB BY ABOUT 30 M. THE LATEST ENSEMBLE SCATTER LOW PLOTS...INITIALIZED 12Z/11...SHOW 3 CLUSTERS AT 00Z/14. THE ECMWF CLUSTER IS OVER THE DELMARVA WITH THE 12Z ECMWF ON THE EAST SIDE OF THE ECMWF MEMBERS...FOLLOWED BY THE GEFS MEMBERS ENE OF THE ECMWF...AND THE CMC NORTHEAST OF THE GEFS. GIVEN THE TWO SHORTWAVES RESPONSIBLE FOR THE EAST COAST STORM ARE CURRENTLY OVER THE U.S. AND APPEAR TO BE WELL SAMPLED...THE REASONABLY CONSISTENT GFS/ECMWF/UKMET APPEAR TO BE WOBBLING ABOUT A POINT LIKELY TO VERIFY...ALONG WITH THE SREF MEAN...WILL PREFER A BLEND OF THE 00Z GFS / 12Z ECMWF / 21Z SREF. THE LATEST 00Z UKMET/ECMWF/CMC ARE SIMILAR TO THEIR PREVIOUS RUNS...WITH ONLY SUBTLE WOBBLES IN STRENGTH/POSITION...WILL KEEP THE SAME PREFERENCE BUT REPLACING THE 12Z ECWMF WITH THE 00Z ECMWF. SURFACE LOW TRACKING FROM EASTERN MONTANA TO THE GREAT LAKES THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 00Z GFS / 00Z ECMWF CONFIDENCE: AVERAGE MUCH TIGHTER CLUSTERING IS SEEN IN THE LATEST ENSEMBLE SCATTER LOW PLOTS WITH GFS/ECMWF TRENDING TOWARD EACH OTHER IN POSITION...RIGHT ON TOP OF THE 12Z UKMET/CMC BY 12Z/13. THE 00Z UKMET/CMC HAVE BOTH TRENDED NORTH A TAD...WHILE THE 00Z ECMWF HAS TRENDED SOUTH BY 00Z/14 ACROSS THE GREAT LAKES REGION. THE 00Z ECMWF/UKMET/CMC ARE NOW A FEW MB WEAKER THAN THE NAM/GFS BUT THE BETTER ENSEMBLE CLUSTERING IS TOWARD THE NORTHERN NAM/GFS INCLUDING THE SREF/GEFS/EC MEANS. DUE TO POTENTIAL FOR A NORTH/SOUTH SHIFT IN FUTURE RUNS...A COMPROMISE WILL BE PREFERRED BETWEEN THE NORTHERN/STRONGER NCEP GUIDANCE AND THE SOUTHERN/WEAKER NON-NCEP GUIDANCE. WILL CONTINUE A GFS/ECMWF BLEND FOR THE PREFERENCE. SHORTWAVE TO REACH THE PACIFIC NORTHWEST WED NIGHT AND DIVE INTO THE SOUTHEAST BY SAT MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 00Z NAM...00Z GFS...00Z ECMWF CONFIDENCE: AVERAGE THE 12Z CMC IS BY FAR THE MOST AMPLIFIED WITH THE UPPER TROUGH AS IT DIGS INTO THE SOUTHEAST SAT MORNING...OUTSIDE OF THE ENSEMBLE DISTRIBUTION...BUT THE 00Z CMC HAS COME BACK TOWARD THE CONSENSUS ALBEIT STRONGER THAN THE REMAINING GUIDANCE. HOWEVER...BOTH THE 00Z UKMET/CMC SHOW A BIT MORE STRENGTH IN THE SOUTHERN STREAM WAVE DIVING INTO THE SOUTHEAST. THE GFS/ECMWF/UKMET HAVE BEEN CONSISTENT OVER THE PAST 3 CYCLES (CONSIDERING 12 & 00Z ONLY)...BUT GIVEN THE ENSEMBLE DISTRIBUTION SUPPORTING A GFS/ECMWF DEPTH/SPEED...WILL SIDE WITH THEM OVER THE MORE AMPLIFIED UKMET. THE 00Z NAM ALSO MATCHES THE GFS/ECMWF. SHORTWAVE TO REACH THE PACIFIC NORTHWEST FRI MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THERE IS REASONABLY GOOD MODEL AGREEMENT HERE...WITH SOME MINOR TIMING ISSUES. THE MODELS HAVE SHOWN LITTLE ADJUSTMENT OVER THEIR PAST FEW CYCLES...AND SHOW ENOUGH AGREEMENT TO INCLUDE A GENERAL MODEL COMPROMISE THROUGH SAT MORNING. www.wpc.ncep.noaa.gov/html/model2.shtml... OTTO