MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1050 AM EST SAT FEB 15 2014 VALID FEB 15/1200 UTC THRU FEB 19/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ***THE 12Z NAM AND 12Z GFS ARE DELAYED IN ARRIVING*** ...MODEL EVALUATION INCLUDES THE 06Z NAM/06Z GFS/00Z UKMET/00Z GEM GLOBAL AND 00Z ECMWF... ...RAPIDLY DEEPENING SURFACE LOW LIFTING UP ALONG THE MID-ATLANTIC/NEW ENGLAND COASTS... PREFERENCE: BLEND OF THE 06Z GFS/00Z ECMWF CONFIDENCE: ABOVE AVERAGE A STRONG SHORTWAVE SEEN ON WATER VAPOR IMAGERY CROSSING THE MID-ATLANTIC REGION THIS MORNING WILL BE AMPLIFYING AS IT MOVES NEWD OFFSHORE THIS AFTERNOON AND LIFTS UP TOWARD COASTAL NEW ENGLAND TONIGHT AND EARLY SUN. THE STRONG HEIGHTS FALLS WILL DRIVE A RAPIDLY INTENSIFYING AREA OF SURFACE LOW PRESSURE THAT WILL BE CROSSING NEAR THE BENCH MARK THIS EVE AND THEN LIFTING ACROSS THE GULF OF MAINE AND INTO NOVA SCOTIA BY EARLY SUN. THE 06Z AND 00Z MODELS ARE IN REASONABLY GOOD MASS FIELD AGREEMENT AT LEAST ON THE LARGER SCALE...ALTHOUGH THE 00Z GEM GLOBAL APPEARED TO BE A LITTLE EAST OF THE GLOBAL MODEL CONSENSUS. THE 06Z GFS AND 00Z ECMWF SHOW VERY GOOD MODEL CLUSTERING AND HAVE THE SUPPORT OF THEIR RESPECTIVE ENSEMBLE MEANS...SO A 06Z GFS/00Z ECMWF BLEND SHOULD SUFFICE ATTM. ...CLIPPER SYSTEM SLIDING ACROSS THE MID-ATLANTIC ON SUNDAY... PREFERENCE: GENERAL MODEL CONSENSUS CONFIDENCE: ABOVE AVERAGE ON THE HEELS OF THE INITIAL SYSTEM IMPACTING THE MID-ATLANTIC AND NEW ENGLAND...ANOTHER WEAK SHORTWAVE/CLIPPER SYS WILL SLIDE DOWN ACROSS THE MIDWEST AND INTO THE OH VLY BY EARLY SUN. THIS SYS SHOULD CROSS THE MID-ATLANTIC BY LATE SUN. THE MODELS ARE GENERALLY IN VERY GOOD AGREEMENT WITH THE MASS FIELDS OF THIS NEXT FEATURE...AND SO A GENERAL MODEL CONSENSUS WILL BE PREFERRED. ...UPPER TROUGH IMPACTING THE PACIFIC NORTHWEST LATE TODAY... ...SPLIT FLOW TROUGH CROSSING THE CENTRAL CONUS... ...DEEPENING SURFACE LOW CROSSING THE OH VALLEY/LOWER GREAT LAKES MONDAY AND TUESDAY... PREFERENCE: BLEND OF THE 00Z ECMWF/00Z ECENS MEAN CONFIDENCE: BELOW AVERAGE A WELL-DEFINED UPPER TROF ADVANCING TOWARD THE PACIFIC NORTHWEST WILL BE ACCOMPANIED BY A STRONG LOW CENTER WHICH WILL PUSH INTO COASTAL BRITISH COLUMBIA BY LATER TONIGHT. AS THE HEIGHT FALLS EJECT INLAND...MODELS CONTINUE TO ADVERTISE THE SYSTEM ADVANCING EASTWARD IN TWO PARTS AS SPLIT FLOW SETS UP. A NRN STREAM WAVE WITH AN ESTABLISHED SFC CYCLONE SHOULD TRACK ACROSS S CNTRL CANADA WHILE A SRN STREAM SYS PROGRESSES THROUGH THE CNTRL U.S. AND APPROACHES THE OH VLY AND GRT LAKES REGION MON AND TUES. THE MODELS REMAIN AT ODDS WITH THE TIMING OF THE COMPLEX ARRAY OF ENERGY AS IT ADVANCES EAST. THE 06Z NAM AND 06Z GFS ARE MORE PROGRESSIVE WITH THE EVOLVING SPLIT FLOW PATTERN...WITH THE 00Z UKMET/00Z GEM GLOBAL AND 00Z ECMWF ALL SLOWER. THE 00Z UKMET BECOMES QUITE THE SLOW AND DEEP OUTLIER WITH THE SRN STREAM SYS IMPACTING THE OH VLY AND GRT LAKES REGION MON AND TUES. THE 06Z GEFS MEAN SUPPORTS THE FASTER GFS/NAM CAMP...WITH THE 00Z ECENS MEAN SUPPORTING THE SLOWER GEM GLOBAL/ECMWF SOLNS. RUN TO RUN CONTINUITY PROBS CONTINUE TO PLAGUE THE MODELS WITH THE ENERGY AS IT ADVANCES ACROSS THE CONUS...BUT THE 00Z ECMWF/00Z ECENS MEAN SOLNS AT LEAST ATTEMPT TO CLUSTER WELL WITH THE GEM GLOBAL AND SPLIT THE DIFF BETWEEN THE SLOW/DEEP UKMET AND THE FASTER/WEAKER GFS/NAM CAMP. ...ADDITIONAL PACIFIC ENERGY AFFECTING THE PACIFIC NORTHWEST BY LATE TUESDAY... PREFERENCE: BLEND OF THE 06Z GEFS MEAN AND 00Z ECENS MEAN CONFIDENCE: BELOW AVERAGE GIVEN THAT THE MEAN LYR FLOW IS REVERTING BACK TO BEING MORE ZONAL IN NATURE...A SERIES OF IMPULSES WILL TRACK TOWARD THE PACIFIC NORTHWEST. THE 06Z NAM AND 06Z GFS TO A LESSER EXTENT ARE A BIT MORE PROGRESSIVE THAN THE GLOBAL MODEL CONSENSUS...WITH THE 00Z UKMET/00Z GEM GLOBAL AND 00Z ECMWF ALL A LITTLE SLOWER. THE UNCERTAINTY IS RATHER HIGH GIVEN THE FAST MOVING FLOW AND LOW AMPLITUDE NATURE OF THE INDIVIDUAL WAVES. WILL LEAN TOWARD THE ENSEMBLE MEANS TO HANDLE THE NATURE OF THIS FLOW WITH CONFIDENCE BELOW AVERAGE. www.wpc.ncep.noaa.gov/html/model2.shtml... ORRISON