MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1242 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. 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 CONFIDENCE 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. POSITIVELY TILTED TROUGH IN BRITISH COLUMBIA SUPPORTING SFC LOW EMERGING EAST OF THE ROCKIES LATE SUNDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET 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. 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. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA