MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 107 AM EDT THU MAR 24 2016 VALID MAR 24/0000 UTC THRU MAR 27/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION INCLUDING PREFERENCE AND FORECAST CONFIDENCE CLOSED LOW IN CENTRAL PLAINS LIFTING THRU GREAT LAKES EARLY FRIDAY AND SHEARING OUT ACROSS N NEW ENGLAND BY SAT WITH ASSOCIATED DEEP SURFACE LOW ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CMC BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE SMALL DIFFERENCES IN OVERALL MODEL SUITE EXIST ACROSS THE PLAINS/GREAT LAKES BUT NOTHING TO GLARING...THIS CONVERGENCE CONTINUES FURTHER INTO NEW ENGLAND BY FRIDAY NIGHT/SATURDAY MORNING GIVEN THE 00Z GFS CONTINUES ITS TREND TOWARD A WEAKER SHEARED OUT FEATURE TO CONVERGE TOWARD A WEAKER/SHEARED OUT SYSTEM WITH A SURFACE PATTERN THAT TRENDS TOWARD SOLID AGREEMENT IN THE 00Z NAM/12Z ECMWF/ECENS MEAN. THIS INCLUDES THE PLACEMENT OF TIMING OF THE SURFACE FRONT ACROSS THE SOUTHEAST INTO THE EASTERN GULF. THE 12Z CMC DEVELOPS A WAKE MID-LEVEL TROF THAT LEADS TO A DEEPER SURFACE REFLECTION SOUTHWEST OF MUCH OF THE OTHER GUIDANCE SUPPORT ACROSS THE HUDSON CANYON AREA S OF LONG ISLAND BY SAT MORNING. BOTH FEATURES RESULT IN EXCLUSION IN AN OTHERWISE GOOD CONSENSUS. NON-CMC BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. UPPER LOW SHEDDING ENERGY INTO THE PACIFIC NORTHWEST TONIGHT/THURS WITH ASSOCIATED COLD FRONT MOVING INLAND...REACHING THE HIGH PLAINS FRI WITH SURFACE CYCLOGENSIS OVER THE NORTHERN HIGH PLAINS WEAKENING INTO THE NW GREAT LAKES SAT EVENING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/12Z ECMWF BLEND CONFIDENCE: AVERAGE MODELS HAVE CONTINUED TO TREND TOWARD A COMMON SOLUTION THOUGH INTERNAL DETAILS: STRENGTH/TIMING ARE STILL SLIGHTLY OFF IN PLACES PARTICULARLY ACROSS THE LOWER MISSOURI/MID-MISSISSIPPI VALLEY BY THE END OF THE PERIOD GIVEN INTERACTION/PLACEMENT DIFFERENCES IN THE SOUTHERN STREAM OF THE SPLIT FLOW. THE 00Z NAM REMAINS A BIT STRONGER AS THE SURFACE REFLECTION ACROSS THE NORTHERN PLAINS WEAKENS SAT MORNING. THE 00Z GFS REMAINS A BIT FASTER THAN MOST OF THE GUIDANCE BY THE END OF THE PERIOD BUT HAS SHIFTED BACK WEST AND HAS BETTER AGREEMENT WITH THE PRIOR 12Z ECMWF PREFERENCE ALONG WITH ENSEMBLE SUPPORT IN THE 12Z ECENS MEAN/21Z SREF AND 18Z GEFS MEAN; THOUGH REMAINS FASTER DUE TO SOUTHERN STREAM DIFFERENCES ACROSS MO/AR MAKING IT LESS FAVORABLE THERE. THE 12Z CMC IS TOO DEEP/STRONG ACROSS THE CENTRAL PLAINS DUE TO INCREASED PHASING WITH THE SOUTHERN STREAM AS WELL AS A SLOWER DIGGING TROF OUT OF THE NORTHERN STREAM THAT ENHANCES THE TROF ACROSS THE NORTHERN PLAINS WITHIN THE OTHER GUIDANCE. TO BEST REPRESENT THE FAIRLY AGREEABLE ENSEMBLE MEANS...WILL SUPPORT A 00Z GFS/12Z ECMWF BLEND AT AVERAGE CONFIDENCE GIVEN ALL THE INTERNAL MOVING PARTS THAT HAVE NOT SETTLED DOWN/ESTABLISHED SOME OVERALL CONSISTENCY. SECONDARY SHORTWAVE DROPPING THROUGH THE INTERMOUNTAIN WEST/HIGH PLAINS ON FRI/SAT AND EJECTING INTO SOUTHERN PLAINS SUN...SOUTHERN PLAINS SURFACE CYCLOGENESIS FRI/SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/12Z UKMET BLEND CONFIDENCE: SLIGHTLY BELOW AVERAGE OVERALL MODEL AGREEMENT IS IN FAIRLY GOOD AGREEMENT MOVING THROUGH THE INTERMOUNTAIN WEST...THOUGH THE ECMWF/ECENS MEAN LAG THE OVERALL BETTER CLUSTERED GUIDANCE THAT IS MORE PROGRESSIVE; BY THE END OF THE PERIOD THE 12Z ECMWF IS STRONGER THAN THE ECENS MEAN RESULTING IN A DEEPER AND SLOWER SURFACE WAVE THAT IS NOT WELL REPRESENTED IN THE 12Z ENSEMBLE SURFACE CLUSTER ANALYSIS OVERALL. THE 00Z NAM REMAINS DISTINCTLY STRONGER/CONSOLIDATED LIKE THE 12Z ECMWF. THE 12Z CMC IS UNCHARACTERISTICALLY FAST PARTICULARLY SAT NIGHT INTO SUNDAY EJECTING RAPIDLY INTO THE SOUTHERN PLAINS A BIT MORE AND DEVELOPING A BROAD SURFACE REFLECTION AND APPEARS TO BE THE GREATEST OUTLIER FROM THE ENSEMBLES AND OTHER DETERMINISTIC RUNS MAKING IT LESS FAVORABLE. OVERALL MODELS SEEM TO TREND NEAR A MIX OF THE 21Z SREF/12Z ECENS MEAN. THIS SEEMS BEST REPRESENTED BY THE 12Z UKMET/00Z GFS. CONFIDENCE REMAINS SLIGHTLY BELOW AVERAGE GIVEN THE SPREAD AND INCONSISTENCY OF SOME OF THE MIDDLE GROUND/PREFERRED MODELS. UPPER TROUGH/FRONT APPROACHING THE PACIFIC NORTHWEST BY LATE SAT/SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS/12Z ECMWF BLEND CONFIDENCE: AVERAGE A DEEP UPPER TROF WILL APPROACH THE PAC NORTHWEST SAT WITH AN ACCOMPANYING COLD FRONT. OVERALL THE DIFFERENCES ALOFT SEEM TO BE GENERALLY RELATED TO THE STRENGTH DIFFERENCES OF THE PRECEDING SHORTWAVE RIDGE WITH THE GFS/NAM/UKMET MORE AMPLIFIED RIDGE COMPARED TO A FLATTER ECMWF/CMC. THERE ARE SMALL DIFFERENCES IN TIMING AND PLACEMENT OF THE SURFACE LOW AS IT APPROACHES THE BC COAST. THE ENSEMBLE MEANS (ECENS/GEFS/SREF) SUPPORT THE NORTHERN MEMBERS BEST REPRESENTED BY THE 12Z ECMWF/00Z GFS...HOWEVER AN OVERALL MODEL BLEND MAY SUFFICE AS WELL. SPREAD IS MODERATE SO CONFIDENCE IS AS WELL. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA