MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1119 PM EST MON MAR 07 2016 VALID MAR 08/0000 UTC THRU MAR 11/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SPLIT-FLOW TROUGH CROSSING THE NORTHERN PLAINS/UPPER MIDWEST... ...SURFACE LOW CROSSING THE UPPER MIDWEST TROUGH TUES... ...COLD FRONT SETTLING ACROSS THE GREAT LAKES/NORTHEAST BY THURS... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: ABOVE AVERAGE THE GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT WITH THE DETAILS OF THE SPLIT-FLOW TROUGH EJECTING ACROSS THE THE NORTHERN PLAINS AND UPPER MIDWEST THROUGH TUES. ALL OF THE MODELS TAKE A WELL-DEFINED LOW CENTER UPPER MS VALLEY TUES AND THEN ACROSS ONTARIO/QUEBEC WED AND THURS AS A TRAILING COLD FRONT SETTLES SOUTHEAST ACROSS THE REGION...INCLUDING THE GREAT LAKES AND NORTHEAST. STRONGER MODEL CLUSTERING OVERALL TENDS TO SUPPORT A 00Z GFS/12Z ECMWF CONSENSUS AT LEAST THROUGH EARLY THURS. ...SHORTWAVE TROUGH TRAVERSING THE NORTHERN TIER TUES-THURS... ...SURFACE LOW DEVELOPING OVER THE MIDWEST AND TRAVERSING THE NORTHEAST... PREFERENCE: 00Z GFS CONFIDENCE: SLIGHTLY BELOW AVERAGE THE MODELS SHOW A PROGRESSIVE SHORTWAVE CROSSING THE NORTHWEST THROUGH TUES THAT WILL EJECT ACROSS THE NORTHERN TIER STATES THROUGH THURS. THE 12Z ECMWF BECOMES THE WEAKEST/FLATTEST SOLUTION WITH THE SHORTWAVE ENERGY AND TRACKS ITS SURFACE LOW FROM THE MIDWEST THROUGH THE NORTHEAST A BIT SOUTH OF THE MODEL CONSENSUS AND SUGGESTS A FARTHER SOUTH FRONTAL ZONE LATE THURS AND FRI. THE 12Z CMC IS THE SLOWEST SOLUTION WITH THE ENERGY AND SURFACE WAVE. THE 00Z NAM/00Z GFS AND 12Z UKMET SPLIT THE DIFFERENCE...BUT THE 12Z UKMET APPEARS TO BE A LITTLE TOO STRONG WITH ITS SURFACE WAVE. WILL LEAN TOWARD THE 00Z GFS AT THIS TIME WHICH APPEARS TO REFLECT THE MODEL CONSENSUS THE BEST. ...UPPER TROUGH/CLOSED LOW AMPLIFYING OVER THE SOUTHWEST... ...DEEP CLOSED LOW CROSSING NORTHERN MEXICO TUES/WED... ...SURFACE LOW DEVELOPING OVER LOWER RIO GRANDE VALLEY... PREFERENCE: 12Z ECENS MEAN CONFIDENCE: BELOW AVERAGE THE MODELS CONTINUE TO EXHIBIT A BIT OF SPREAD WITH THE STRONG HEIGHTS FALLS DIGGING DOWN FROM SOUTHERN CA INTO NORTH-CENTRAL MEXICO THROUGH TUES AND WED. THE 12Z UKMET/12Z CMC AND 12Z ECMWF ALL TAKE AN ANOMALOUSLY STRONG CLOSED LOW FARTHER SOUTH INTO MEXICO VERSUS THE 00Z NAM AND 00Z GFS. ON THURS...ALL OF THE MODELS AGREE IN GRADUALLY LIFTING THE CLOSED LOW EAST-NORTHEAST TOWARD OR EVEN ACROSS THE LOWER RIO GRANDE VALLEY. THIS WILL FOSTER BROAD SURFACE CYCLOGENSIS OVER SOUTHERN TX WHICH WILL SLOWLY APPROACH THE LOWER MS VALLEY BY EARLY FRI. THE 12Z ECMWF IS THE FARTHEST SOUTH SOLUTION BY THE END OF THE PERIOD STILL WITH THE CLOSED LOW...WITH THE 12Z CMC A LITTLE EAST OF THE ECMWF...AND THE UKMET A LITTLE NORTHEAST. THE 00Z NAM AND 00Z GFS SUGGEST MORE PROGRESSION OF THE ENERGY THROUGH EASTERN TX AND INTO THE LOWER MS VALLEY. BASED ON THE LEVEL OF SPREAD THAT STILL EXISTS...WILL TAKE AN ENSEMBLE APPROACH AND FAVOR THE 12Z ECENS MEAN WHICH OFFERS A CONSENSUS SOLUTION THAT SPLITS THE DIFFERENCE BETWEEN NCEP AND NON-NCEP CAMPS. ...SHORTWAVE TROUGH/FRONT MOVING INTO THE NORTHWEST ON TUES... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW A SHORTWAVE IMPULSE AND ASSOCIATED FRONT MOVING INTO THE NORTHWEST ON TUES. THE 00Z NAM IS A BIT SLOWER THAN THE MODEL CONSENSUS. THE REMAINING GUIDANCE IS WELL CLUSTERED WITH THIS SYSTEM...AND SO A NON-NAM CONSENSUS WILL BE PREFERRED. ...DEEP SOUTHWEST FLOW/ENERGY AIMING INTO THE NORTHWEST WED/THURS... PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE STRONG DEEP LAYER SOUTHWEST FLOW WITH EMBEDDED SHORTWAVE IMPULSES WILL BE AIMING FOR THE PACIFIC NORTHWEST BY LATE WED AND THURS. THIS WILL BE FACILITATED BY THE PRESENCE OF A DEEP GULF OF AK VORTEX AND STRONG JET ENERGY ROUNDING THE BASE OF THE LARGER SCALE UPPER TROUGH. ONE IMPULSE ALONG WITH A RAPIDLY DEEPENING SURFACE LOW WILL MOVE OFFSHORE WA/OR AND VANCOUVER ISLAND BY LATE WED WHICH WILL DRIVE A COLD FRONT INLAND ACROSS THE NORTHWEST ON THURS. THE 00Z NAM AND 12Z CMC ARE MORE AMPLIFIED THAN MODEL CONSENSUS WITH THE SHORTWAVE AND TEND TO WRAP THE SURFACE LOW A BIT LEFT OF THE 00Z GFS/12Z UKMET AND 12Z ECMWF. THE 00Z GFS AND 12Z ECMWF CLUSTER TOGETHER BETTER AND HAVE STRONGER ENSEMBLE SUPPORT...SO WILL PREFER A GFS/ECMWF CONSENSUS HERE WITH THIS FEATURE. ...UPPER TROUGH/SURFACE LOW APPROACHING THE WEST COAST ON FRI... PREFERENCE: 12Z ECMWF CONFIDENCE: SLIGHTLY BELOW AVERAGE THE MODELS SHOW A ROBUST UPPER TROUGH AND ASSOCIATED SURFACE LOW APPROACHING THE WEST COAST BY EARLY FRI ALONG WITH AN ATTENDANT FRONTAL ZONE. THE 00Z NAM IS WEAKER AND MORE PROGRESSIVE THIS SYSTEM. MEANWHILE...THE 00Z GFS IS THE DEEPEST SOLUTION ALOFT AND IS NOW THE FARTHEST SOUTH WITH THE HEIGHT FALLS AND SURFACE LOW. THE 12Z UKMET IS A BIT NORTH WITH THE LOW TRACK COMPARED TO THE MODEL CONSENSUS...WITH THE 12Z CMC AND 12Z ECMWF JUST A TAD FARTHER SOUTH. THE 12Z ECMWF APPEARS TO REFLECT THE MODEL CONSENSUS THE BEST AND HAS BETTER ENSEMBLE SUPPORT FROM THE 18Z GEFS MEAN AND 12Z ECENS MEAN. SO..WILL LEAN TOWARD THE 12Z ECMWF WITH THIS SYSTEM...BUT WITH SOMEWHAT LIMITED CONFIDENCE GIVEN THE DETERMINISTIC MODEL SPREAD. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON