MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1230 PM EDT SUN MAR 23 2014 VALID MAR 23/1200 UTC THRU MAR 27/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE SWINGING THROUGH THE MID-ATLANTIC STATES TODAY... ...SURFACE LOW LIFTING INTO THE CANADIAN MARITIMES ON MON... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE A SHORTWAVE TROUGH WILL CROSS THE MID-ATLANTIC STATES TODAY AND MOVE OFFSHORE OVERNIGHT WHILE FOSTERING SFC LOW CYCLOGENESIS WELL OFF THE EAST COAST THIS AFTERNOON. THE LOW CENTER WILL LIFT NEW INTO THE CANADIAN MARITIMES ON MON. THE NAM IS A LITTLE SLOWER THAN THE MODEL CONSENSUS...WITH THE REMAINING GLOBAL MODELS WELL CLUSTERED TOGETHER MASS FIELD WISE. A NON-NAM CONSENSUS WILL BE PREFERRED. ...AMPLIFYING TROUGH OVER THE EASTERN U.S. MON AND TUES... ...CYCLOGENESIS OVER THE NORTHEAST GULF OF MEXICO LATE MON... ...RAPIDLY INTENSIFYING SURFACE LOW OFF THE SOUTHEAST/MID-ATLANTIC/NEW ENGLAND TUES AND WED... PREFERENCE: BLEND OF THE 00Z ECMWF AND 00Z ECENS MEAN CONFIDENCE: BELOW AVERAGE THE UPR PATTERN BEGINS WILL BE QUITE AMPLIFIED OVER THE NEXT COUPLE OF DAYS WITH A LARGE POSITIVE HEIGHT ANOMALY INITIALLY SETTING UP ACROSS THE WESTERN U.S. AND AN INCREASINGLY AMPLIFIED EASTERN U.S. LONGWAVE TROUGH WHICH WILL BE ENHANCED BY THE DIGGING OF A WELL-DEFINED SHORTWAVE TROUGH DIGGING FROM THE DAKOTAS SEWD INTO THE OH/TN VALLEYS BY EARLY TUES AND THEN NEWD OFFSHORE NEW ENGLAND ON WED. THIS FEATURE IS OF SIGNIFICANT IMPORTANCE AS IT ALLOWS FOR THE LARGER SCALE TROUGH APPROACHING THE EAST COAST TO BEGIN TAKING ON A NEGATIVE TILT...AND IT WILL BE INTERACTING WITH A STRONG FRONTAL ZONE OVER THE GULF OF MEXICO AND JUST OFFSHORE THE SOUTHEAST COASTLINE. THE GUIDANCE AGAIN SHOWS SIGNIFICANT CYCLOGENESIS OCCURRING...WITH LOW PRESSURE INITIALLY DEVELOPING OVER THE NERN GULF OF MEXICO AND THEN INTENSIFYING RAPIDLY OFF THE SOUTHEAST AND MID-ATLANTIC COASTS ON TUES BEFORE THEN LIFTING NEWD TWD NOVA SCOTIA ON WED. THE LATEST NAM TENDS TO BE THE STRONGEST SOLN WITH THE DIGGING SHORTWAVE TROUGH...ESP AS IT CROSSES THE MID-ATLANTIC REGION. AS A RESULT...THE NAM FAVORS A STRONGER SFC LOW CROSSING THE OH VLY AND MID-ATLANTIC AND A SHARP WWD EXTENDING INVERTED TROUGH ON TUES THAT THE GLOBAL MODEL CONSENSUS DOES NOT FAVOR. THE 00Z UKMET AND 00Z GEM GLOBAL TEND TO BE THE STRONGEST AND MORE AMPLIFIED SOLNS RELATING TO THE NEG-TILTED UPR TROUGH AND CORRESPONDING EXPLOSIVE DEEPENING OF SFC LOW PRESSURE OFFSHORE THE SOUTHEAST AND MID-ATLANTIC COASTS. THE 00Z ECMWF IS A LITTLE WEAKER...AND THE 12Z GFS IS SEEN AS THE WEAKEST WITH THE INTENSIFICATION OF THE SFC LOW...BUT ALL MODELS INCLUDING THE NAM EVENTUALLY FAVOR A RAPIDLY INTENSIFYING LOW THAT LIFTS NORTH OFFSHORE THE EAST COAST AND A FEW DEGREES EAST OF THE 40N/70W BENCHMARK. THE STRONGER UKMET IS FARTHEST LEFT WITH THE LOW TRACK. THE NAM AND GEM ARE FARTHEST EAST. THE GFS AND ECMWF SPLIT THE DIFF...BUT THE GFS BECOMES THE FASTEST SOLN IN TIME. ACCOUNTING FOR THE SPREAD....AND WITH SUPPORT FROM THE LATEST GEFS MEAN AND ESP THE ECENS MEAN...THE ECMWF HAS THE STRONGEST SUPPORT. GIVEN BETTER RESOLUTION ON THE ECENS MEAN...WOULD PREFER TO BLEND IT WITH THE ECMWF ATTM...BUT CONFIDENCE IS AGAIN LIMITED GIVEN THE SPREAD WITH INTENSITY AND TO A DEGREE TIMING OFFSHORE THE EAST COAST. ...SOUTHERN STREAM TROUGH/CLOSED LOW OVER THE SOUTHWEST SHEARING DOWNSTREAM... PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF CONFIDENCE: ABOVE AVERAGE AS AN UPR RIDGE BUILDS ACROSS THE WESTERN U.S. EARLY IN THE PERIOD...THE MODELS DEPICT ENERGY PINCHING OFF UNDERNEATH IT INVOF SRN CA BY LATE TODAY THROUGH MON. ON TUES...THE ENERGY WILL BEGIN TO SLOWLY ADVANCE EAST ACROSS AZ/NM IN RESPONSE TO A LARGER SCALE TROUGH ADVANCING TWD THE WEST COAST. ON WED...THE ENERGY WILL BE SHEARING DOWNSTREAM ACROSS THE SRN PLAINS. THE 00Z UKMET IS THE WEAKEST MODEL...WITH THE 12Z NAM TENDING TO BE THE SHARPEST AND ESP OVER NRN TX/OK BY LATE WED. WILL PREFER A BLEND OF THE GFS AND ECMWF WHICH CLUSTER MORE STRONGLY. ...UPPER TROUGH APPROACHING THE WEST COAST BY TUES... ...ENERGY ADVANCING ACROSS THE INTERMOUNTAIN WEST BY WED... ...LEE-SIDE CYCLOGENESIS IN THE HIGH PLAINS BY WED... PREFERENCE: BLEND OF THE 00Z ECMWF AND 00Z ECENS MEAN CONFIDENCE: AVERAGE BY EARLY TUES...A WELL-DEVELOPED CLOSED LOW AND BROADER LONGWAVE TROUGH WILL BE POSITIONED JUST OFFSHORE THE WEST COAST...WITH SFC LOW PRESSURE APPROACHING BRITISH COLUMBIA. A PORTION OF THIS TROUGH WILL MOVE INLAND ACROSS THE INTERMOUNTAIN REGION AND WILL FOSTER STRONG CYCLOGENESIS IN THE LEE OF THE ROCKIES ON WED. THE 00Z UKMET AND 00Z GEM GLOBAL ARE A TAD FASTER WITH THE SHORTWAVE ENERGY ALOFT...WITH THE 12Z NAM/12Z GFS AND 00Z ECMWF A BIT SLOWER. BY WED...ALL OF THE MODELS LIKE THE IDEA OF STRONG LOW PRESSURE OVER THE CNTRL HIGH PLAINS...BUT THE GFS/NAM SOLNS SEEM TO FAVOR ONE MAIN LOW CENTER NEAR THE CO/KS BORDER VS THE NON-NCEP SOLNS LIKING THE IDEA OF LOW CENTER OVER ERN CO AND ONE FARTHER NORTH INVOF THE SD/NEB BORDER. A LARGE NUMBER OF ECENS MEMBERS AND SOME GEFS MEMBERS LIKE THE IDEA OF THE NON-NCEP SFC LOW DISTRIBUTION. WILL FAVOR A BLEND OF THE 00Z ECMWF AND 00Z ECENS MEAN TO RESOLVE THE DIFFS ATTM. ...CLOSED LOW LINGERING OFFSHORE THE PACIFIC NORTHWEST ON WED... PREFERENCE: BLEND OF THE 00Z ECENS MEAN AND 06Z GEFS MEAN CONFIDENCE: BELOW AVERAGE THE MODELS INDICATE A CLOSED UPR LOW LINGERING OFFSHORE THE NORTHWEST ON WED ALONG WITH A RELATIVELY INTENSE SFC LOW...AS ADDITIONAL ENERGY ASSOCD WITH THE ORIGINAL UPR TROUGH ADVANCES DOWNSTREAM INTO THE INTERMOUNTAIN WEST. THE 00Z UKMET IS THE WEAKEST SOLN WITH THE ENERGY ALOFT AND THE 12Z NAM IS THE WEAKEST SOLN WITH THE SFC REFLECTION. THE 00Z ECMWF AND 00Z GEM GLOBAL CLUSTER BETTER ALOFT AND HAVE SUPPORT FROM THE 00Z ECENS MEAN AND TO AN EXTENT THE 06Z GEFS MEAN. THE 12Z GFS FOR ITS PART IS SLOWER WITH THE EWD ADVANCEMENT OF ITS CLOSED LOW AND IS THE STRONGEST AT THE SFC. WILL PREFER TO STAY CLOSE TO THE ENSEMBLE MEANS GIVEN THE SPREAD SFC AND ALOFT OVERALL WITH THE MODELS. CONFIDENCE WILL BE LIMITED. www.wpc.ncep.noaa.gov/html/model2.shtml... ORRISON