MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 257 PM EDT SAT OCT 10 2015 VALID OCT 10/1200 UTC THRU OCT 14/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH FINAL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. DEEP LOW STALLING NEAR THE SOUTHEAST COAST SUN/MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 12Z OPERATIONAL MODELS CONFIDENCE: ABOVE AVERAGE FAIRLY STRONG RUN TO RUN CONTINUITY CONTINUES WITH THE EVOLUTION OF THE CUT-OFF AND EVENTUAL SHIFT NORTHEAST OFF THE EASTERN SEABOARD AS THE UPSTREAM TROF DEEPENS INTO TUESDAY. THE 00Z ECMWF ENSEMBLE CONTINUE TO REMAIN TIGHTLY PACKED BUT ALSO SLIGHTLY DEEPER THAN THE 00Z GEFS/CMCE MEMBERS AND AS SUCH LAG THE LIFT TOWARD THE NORTHEAST...THOUGH THE 06Z GEFS HAS TRENDED TOWARD THIS SOLUTION AS WELL. THE 12Z CMC HAS BACKED OFF THE DEEP SURFACE CYCLONE AND THE UKMET HAS TRENDED A BIT MORE CONSOLIDATED AND CENTRALIZED WITH THE VORT ENERGY OFF THE CAROLINA COAST... GIVEN THEIR AGREEMENT TO THE EARLIER PREFERENCE THEY COULD BE ADDED. AS SUCH THE OFFICIAL PREFERENCE IS NOW A 12Z OPERATIONAL MODEL BLEND. DEEP CYCLONE MOVING THROUGH SOUTHERN CANADA THROUGH MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CMC BLEND CONFIDENCE: AVERAGE THERE IS A GENERAL AGREEMENT WITH THE TIMING OF THE FRONTAL ZONE AND SURFACE LOW IN TX WITH MUCH OF THE DETERMINISTIC AND ENSEMBLE GUIDANCE AS THE OVERALL SYSTEM TRACKS EAST AND STRETCHES MERIDIONALLY OVER THE EASTERN THIRD OF THE U.S IN THE EARLY PART OF NEXT WEEK. LARGEST DIFFERENCES APPEAR TO BE PRIMARILY IN CANADA WITH SOME LEAKING AFFECTS ACROSS INTO THE BOUNDARY WATERS OF MN AND SURROUNDING LAKE SUPERIOR. MUCH OF THIS DIFFERENCE APPEARS TO BE IN RELATION TO THE LEE-CYCLONE AND ITS OCCLUSION/INTERACTION WITH A SURFACE WAVE/TRIPLE POINT MOVING NORTH ON SUNDAY NIGHT/MON. ENSEMBLE SURFACE LOW CLUSTER INDICATES INCREASING SPREAD AFTER 12/00Z...THOUGH THE OPERATIONAL RUNS APPEAR TO BE GENERALLY STRONGER AND SOUTH AND WEST WITHIN THEIR OWN ENSEMBLE CLUSTERS. THE 09/12Z AND 10/00Z ECMWF OPERATIONAL RUNS MAY BE GOOD EXAMPLES HAVING A STRONG SURFACE LOW OVER SW ONTARIO STANDING OUT SIGNIFICANTLY FROM THE UKMET/NAM/GFS/CMC/SREF SOLUTIONS....ALLOWING FOR INCREASED QPF FROM ACTIVE CONVEYOR BELT WRAPPING BACK AROUND THE CYCLONE INTO MN. THE 00Z ECENS MEAN APPEARS TO BE A FAIRLY GOOD COMPROMISE WITH OTHER MODEL SOLUTIONS. THE 12Z ECMWF WEAKENED THE SURFACE REFLECTION BUT RETAINS A BIT OF THE TROF/CYCLONIC WRAP IN MOISTURE AND QPF...BUT THE TRIPLE POINT/NEW SURFACE LOW TRACKS WELL WITH THE UKMET/NAM/GFS... ACROSS JAMES BAY MONDAY NIGHT...MUCH MORE IN LINE WITH THE 00Z ECENS MEAN...ALLOWING BETTER CONFIDENCE IN BLENDING IT BACK IN TO THE PREFERENCE. THE 00Z GEFS CLUSTER IS QUITE TIGHT AROUND THE 00Z GFS OPERATIONAL AND THE 12Z GFS RETAINS GOOD CONTINUITY WITH ITS EARLIER RUNS. THE ONLY CONCERN WITH THE 12Z GFS ITS HABITUAL DRYNESS ALONG THE FRONT...AND GIVEN THIS BIAS IT GETS A BIT FORWARD ACROSS THE EASTERN U.S. WITH THE FRONT TO WEIGHT IT A BIT LOWER THERE BY DAY 3...OTHERWISE PRIOR TO DAY 3 IT SHOULD BE CENTRAL TO THE BLEND. THE 12Z NAM IS QUITE AGREEABLE WITH THE 12Z GFS AND GIVEN IT IS A BIT SLOWER WITH THE BASE OF THE TROF AND COLD FRONT INTO THE APPALACHIANS...PROVIDES BETTER STRENGTH/AGREEMENT WITH THE 12Z ECMWF. THE 12Z UKMET ALSO SLOWED AND DRAMATICALLY SHIFTED SOUTH WITH THE TRACK OF THE SURFACE LOW...STRONGLY CLUSTERED WITH THE 12Z NAM/GFS/ECMWF/ECENS MEAN/GEFS...HOWEVER IT MIMICS THE 12Z GFS BECOMING A BIT FAST ACROSS THE BASE OF THE TROF OVER THE EAST COAST BY DAY 3. THE 12Z CMC HAS A SIMILAR EVOLUTION TO THE LESSER PREFERRED 00Z ECMWF RUN WITH A STRONGER OCCLUSION RETAINING IT INSTEAD OF FOCUSING THE ENERGY TOWARD THE NEW CENTER/TRIPLE POINT AND IS THE SLOWEST WITH THE BASE OF THE TROF THROUGH THE TENNESSEE VALLEY. GIVEN STRENGTHENING OF AGREEMENT IN THE MODELS...WITH THE 00Z ECENS MEAN ONLY THE 12Z CMC SIGNIFICANTLY STANDS OUT THROUGHOUT THE ATMOSPHERE...LAGGING THE MAIN CONSENSUS TYPICAL OF ITS BIAS. THIS MAKES THE PREFERENCE A NON-CMC BLEND BUT WITH GOOD AMOUNT OF DIFFERENCE THROUGH THE TROF/SURFACE FRONT THE CONFIDENCE IS NORMAL OR AVERAGE WEAK SYSTEM MOVING ACROSS WESTERN/CENTRAL CANADA WEAK SURFACE WAVE/WARM FRONT CROSSING THE NORTHERN PLAINS TUESDAY/WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 12Z OPERATIONAL MODELS CONFIDENCE: ABOVE AVERAGE GENERALLY FLAT WNWLY FLOW IS PROGGED WITH A WEAK SPEED MAX SHORTWAVE IN THE FLOW... THIS WILL ADVANCE A WARM FRONT. THE 12Z UKMET SLOWED AND ALONG WITH THE 12Z CMC CLOSE A WEAK SURFACE LOW BY THE END OF THE FORECAST PERIOD. THIS IS SUPPORTED BY A FEW CMC AND 00Z ECMWF ENSEMBLE MEMBERS...THAT BLENDING THE 12Z OPERATIONAL MODELS SHOULD BE A GOOD SOLUTION TO STABILIZE SMALL DETAILS. UPPER LOW MOVING OFFSHORE BAJA CALIFORNIA SURFACE LOW MOVING NORTHWEST OFFSHORE BAJA CA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 12Z OPERATIONAL MODELS CONFIDENCE: SLIGHTLY ABOVE AVERAGE NEWER 12Z MODELS CONSOLIDATED A BIT MORE EVEN BELOW 7H... AS SUCH GENERAL 12Z OPERATIONAL BLEND IS PREFERRED AT ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA