MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 306 AM EDT FRI OCT 07 2016 VALID OCT 07/0000 UTC THRU OCT 10/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION INCLUDING PREFERENCE AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HURRICANE MATTHEW ~~~~~~~~~~~~~~~~~~~ PREFERENCE: NHC TRACK - NEAR ECMWF/GEFS/UKMET BLEND TIGHT MODEL SPREAD IN THE SHORT TERM UNTIL ABOUT 08/12Z WHEN THE 00Z NAM BREAKS A BIT FURTHER NORTHEAST FOLLOWED CLOSELY BY THE 00Z GFS/18Z GEFS. THE 12Z UKMET IS MIDDLE SOLUTION IN TIMING AS THE CENTER PARALLELS THE SC COAST SAT NIGHT WHILE THE 12Z CMC/ECMWF ARE SLOWER. AS THE VERTICAL SHEAR TAKES HOLD AND WEAKENS THE LOW...A SHIFT OF THE LOW LEVEL CENTER TOWARD THE EAST AND EVENTUALLY SOUTH OCCURS SUN/MONDAY WITH BROAD SPREAD SEEN FROM SW-NE IN THE 12Z ENSEMBLE SURFACE LOW CLUSTER WITH SOLID AGREEMENT THAT AN ANTICYCLONIC LOOP WILL OCCUR MONDAY WITH ONLY A VERY FEW ENSEMBLE MEMBERS (MAINLY NAEFS) LIFTING NORTHEAST INTO THE NORTHERN STREAM. THE 00Z GFS HOWEVER DID SHED THE SURFACE LOW DUE EAST RATHER THAN ENTERING THE LOOP REDUCING OVERALL CONFIDENCE. THE 03Z NHC TRACK IS A NICE MIDDLE GROUND SOLUTION TO THIS SPREAD FAVORING THE 18Z GEFS/12Z UKMET AND THE 12Z ECMWF ON THE SW SIDE. PLEASE REFER TO OFFICIAL NHC FORECAST FOR ADDITIONAL DETAILS. 07Z UPDATE: ALL 3 NON-NCEP MODELS CONTINUE THE AGREEMENT SKIRTING THE GA/SC COAST BUT ALSO HAVE TRENDED TOWARD THE GFS SIDE OF THE SOLUTIONS...FAVORING A FURTHER SHIFT EAST. THE 00Z ECMWF/CMC REMAIN SOUTH OF THE GFS MUCH CLOSER TO THE 18Z GEFS/00Z NAM AND MATCH CLOSEST TO THE 03Z NHC FORECAST. THE 00Z UKMET WAS EVEN FARTHER NORTH THAN THE GFS AS FAR AS 34N BY 84HRS. SHORTWAVE LIFTING ACROSS CENTRAL PLAINS INTO GREAT LAKES MELDING WITH DEEP LOW ACROSS SOUTHERN CANADA FRI/SAT EVENTUALLY TRACKING THROUGH GREAT LAKES/NEW ENGLAND SAT/SUN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE MODELS CONTINUE TO SHOW STRONG AGREEMENT IN TIMING/PLACEMENT AND ORIENTATION OF THE SHORTWAVE AND ASSOCIATED SURFACE LOW/COLD FRONT LIFTING ACROSS THE CENTRAL PLAINS INTO GREAT LAKES TODAY. EVENTUALLY BECOMING THE DOMINANT WAVE ON THE EASTERN SIDE OF THE LARGER SCALE UPPER LOW ALONG THE CANADIAN BOARDER. THIS MELDING AND EVOLUTION TRACKING EASTWARD THROUGH THE GREAT LAKES INTO NEW ENGLAND REMAINS VERY TIGHTLY ALIGNED IN THE MASS FIELDS WITH ONLY SMALL MINOR INTERNAL DIFFERENCES THAT WILL CONTINUE TO VARY FROM RUN TO RUN. OVERALL CONFIDENCE IS VERY HIGH THROUGH 00Z SUNDAY. RAPIDLY MOVING SHORTWAVE ENERGY FROM LOW OFF BC/WA ATTM EVENTUALLY CATCHES THE TRAILING TROF ACROSS NEW ENGLAND AND INDUCES A BIT OF SPREAD ESPECIALLY ALOFT WITH A FASTER CMC/ECMWF COMPARED TO A SLOWER 00Z GFS/NAM. THIS DIFFERENCE ALSO MANIFESTS IN THE SURFACE WAVE THAT DEVELOPS OVER GEORGES BANK EARLY MONDAY. THIS SPREAD IS MILD...BUT GIVEN THE OVERALL SPEED OF THE WAVE...AT 3 DAYS OUT FEEL KEEPING WITH THE GENERAL MODEL BLEND IS APPROPRIATE. 07Z UPDATE: ONLY DIFFERENCES REMAIN AFTER 72HRS IN THE DEPTH OF THE EAST COAST TROF...THE 00Z UKMET IS MUCH DEEPER THAN THE REST OF THE GUIDANCE BUT THIS IS DUE TO SHEARING MORE OF MATTHEW'S ENERGY NORTHWARD THAN THE ENERGY OUT OF THE NORTHERN STREAM. THE ECMWF REMAINS FLATTER AND SLIGHTLY FASTER THAN THE GFS. AS SUCH NO MAJOR CHANGE IN PREFERENCE/CONFIDENCE. POSITIVELY TILTED TROUGH IN BRITISH COLUMBIA SUPPORTING SFC LOW EMERGING EAST OF THE ROCKIES LATE SUNDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE A WELL DEFINED SHORTWAVE AND ASSOCIATED SURFACE LOW IS CURRENTLY MAKING LANDFALL ACROSS WA AS THE LEAD WAVE WITHIN THE LOOSELY DEFINED UPPER LOW ACROSS BRITISH COLUMBIA. THIS WAVE IS SHED EASTWARD TO EVENTUALLY ENHANCE THE TROF OVER THE EAST COAST BY MONDAY (SEE ABOVE). THIS SUPPORTS AN INCREASINGLY ZONAL FLOW ACROSS THE PACIFIC NORTHWEST WITH STRONG/PERSISTENT WESTERLY FLOW/ATMOSPHERIC RIVER EVENT UP THROUGH SUNDAY. ENERGY WITHIN THE ATMOSPHERIC RIVER CROSSES THE NORTHERN ROCKIES AND SUPPORTS BROAD LEE CYCLOGENESIS ACROSS THE NORTHERN TIER MONDAY. THERE IS A SPREAD IN TIMING...AS THE 00Z NAM/GFS ARE GENERALLY SLOW TO THE 12Z UKMET/CMC AND ECMWF BY 3-6 HOURS...HOWEVER THE 12Z UKMET REMAINS MUCH STRONGER AND MORE AMPLIFIED IN THE MIDDLE ATMOSPHERE AND IS REFLECTED BY A DEEPER SURFACE WAVE. THE ENSEMBLES SUPPORT THEIR OPERATIONAL COUNTER PARTS WITH LITTLE DIFFERENCE IN TREND NOTED BY EITHER CAMP. STILL WITH THE UKMET AS THE MAIN OUTLIER TO THE THEME... WILL CONTINUE TO SUPPORT A NON-UKMET BLEND. THE DIFFERENCES IN THE MASS FIELDS MAY SEEM LARGE BUT THE OVERALL PATTERN/SHAPE ARE QUITE COMPLIMENTARY IN A BLEND TO HAVE SOME HIGHER CONFIDENCE IN THIS NON-UKMET BLEND. 07Z UPDATE: THE CMC SLOWED A BIT TOWARD THE END OF THE FORECAST PERIOD CLOSER TO THE NAM/GFS SOLUTIONS AND IS NOW A BIT SLOWER THAN THE MAIN CLUSTER WITH THE TROF AXIS AT 5H. THE UKMET TEMPERED THE STRENGTH EVER SO SLIGHTLY BUT MATCHES WELL TO THE ECMWF. GIVEN THE SPREAD IN TIMING SEEMS MINOR BY DAY 3 STANDARDS WILL INCLUDE THE UKMET AND SUPPORT A GENERAL MODEL BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. N BAJA SHORTWAVE LIFTS INTO DESERT SOUTHWEST SUN AND INTO THE PLAINS BY MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM/GFS AND 12Z ECMWF BLEND CONFIDENCE: AVERAGE GOES WV MOSAIC SHOWS A NICE COMMA HEAD SHORTWAVE ACROSS N BAJA CALIFORNIA AT THIS TIME. MODELS ARE FAIRLY CONSISTENT IN LIFTING THIS NORTHWARD INTO THE DESERT SOUTHWEST/FOUR CORNERS BY SUNDAY STILL IN FAIRLY SOLID AGREEMENT IN SHAPE/TIMING. AFTER SUNDAY THOUGH AS THE SYSTEM SHEARS INTO THE CENTRAL PLAINS...THE 12Z UKMET BECOMES A BIT MORE ELONGATED AND WEAKER OVERALL; WHILE THE 12Z CMC ALSO IN UNCHARACTERISTICALLY FASTER SHIFTING EASTWARD AS WELL. OTHERWISE THE 00Z NAM/GFS AND 12Z ECMWF SEEM WELL ALIGNED THOUGH THE NAM IS A BIT MORE CONSOLIDATED (AS IT TENDS TO DO BY DAY 3). STILL A BLEND OF THE NAM/GFS AND ECMWF SEEMS PRUDENT AT THIS POINT. CONFIDENCE IS AVERAGE. 07Z UPDATE: THE 00Z NON-NCEP MODELS TRENDED TOWARD THE 12Z ECMWF/00Z GFS; THE UKMET NOW IS A BIT MORE AMPLIFIED AND THE CMC IS A BIT SLOWER...ENOUGH SO TO SUPPORT AN OPERATIONAL MODEL BLEND. AS SUCH CONFIDENCE IN ALSO INCREASED TO SLIGHTLY ABOVE AVERAGE GIVEN THERE STILL REMAINS SOME MINOR SPREAD IN MAGNITUDE/SHAPE AND TIMING. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA