MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1101 PM EST FRI MAR 11 2016 VALID MAR 12/0000 UTC THRU MAR 15/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z GUIDANCE EVALUATION INCLUDING MODEL PREFERENCES AND FORECAST CONFIDENCE LONGER WAVELENGTH WAVE NEAR ONTARIO/S HUDSON BAY/CLIPPING NEW ENGLAND WITH ASSOCIATED COLD FRONTAL PASSAGE EARLY SUN MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE FAIRLY STRONG MODEL AGREEMENT EXISTS WITH THE TIMING/STRENGTH AND SHAPE OF THE BROADER WAVE MOVING ACROSS EASTERN CANADA...WITH ASSOCIATED SURFACE LOW THAT WILL DRAPE A COLD FRONT ACROSS THE UPPER GREAT LAKES AND CROSS NEW ENGLAND/N MID-ATLANTIC SUNDAY. FURTHER CLUSTERING EXISTS WITH THE 12Z ENSEMBLE SUITE TO SUPPORT AN OPERATIONAL MODEL BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE...GIVEN THERE REMAINS SOME SPREAD/PLACEMENT OF THE EXACT LOW CENTER WHEN TRANSFERRING FROM CONTINENTAL QUEBEC TO CANADIAN MARITIME ON SUNDAY AFTERNOON. UPPER LOW ACROSS TX SAT...QUICKLY WEAKENING WHILE LIFTING ALONG THE MS RIVER TOWARD GREAT LAKES SUN NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM/GFS AND 12Z ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE MODELS ARE FAIRLY CONSISTENT IN THE LIFTING NORTHWARD OF THE DEEP UPPER LOW OVER TX INTO THE MS VALLEY...SPREAD INCREASES AROUND SUNDAY MORNING BASED ON TIMING/STRENGTH DIFFERENCES LIFTING THROUGH THE MS RIVER VALLEY TOWARD LAKE MICHIGAN. THE 12Z UKMET IS GENERALLY FASTER AND STRONGER LEADING TO A DEEPER SURFACE REFLECTION INTO THE MIDWEST AS WELL AS LIFTING FURTHER NORTH THAN ALL OTHER GUIDANCE. THE 00Z NAM TRENDED TOWARD THE GFS/ECMWF PREFERENCE AND THOUGH REMAINED A BIT STRONGER THAN THE GFS AND EAST OF THE ECMWF. AS SUCH WILL PREFER A 00Z NAM/GFS AND 12Z ECMWF BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. UPPER LOW TROF IN DESERT SOUTHWEST SAT...CROSSING THE SOUTHERN PLAINS SUN NIGHT AND WEAKENING THROUGH THE OH/TN VALLEYS/MID ATLANTIC MON ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM/GFS AND 12Z ECMWF BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM TRENDED SOUTH TOWARD BETTER ALIGNMENT WITH THE PRIOR PREFERENCE/ENSEMBLE MEANS...LEAVING THE 12Z CMC REMAINING AS THE NORTHERN AND SLOWER OUTLIER PARTICULARLY THROUGH 14/12Z. THOUGH THE NAM REMAINS A SLIGHTLY SLOWER MODEL TO THOSE GEFS/ECENS MEANS ECMWF/GFS...IT IS MINOR AND INCLUSION FURTHER STRENGTHENS THE PREFERENCE AND WITH LITTLE CHANGE NOTED IN THE 12Z GFS. A PREFERENCE IS NOW A 00Z NAM/GFS AND 12Z ECMWF BLEND. THE 00Z UKMET IS QUICKEST TO WEAKEN THE CONSOLIDATED WAVE AND OPEN IT ACROSS OZARKS BY LATE SUNDAY...AND REMAINS TOO FAST/FLAT AFTERWARD. CONFIDENCE OVERALL IN A 00Z NAM/GFS AND 12Z ECMWF BLEND REMAINS AT SLIGHTLY ABOVE AVERAGE GIVEN TIGHTENED ENSEMBLE CLUSTER STRENGTH. BROAD LARGE SCALE TROF OFF THE PACIFIC NORTHWEST COAST SHEDDING LEAD ENERGY THROUGH WA/OR SUN MORNING THEN SHIFTING MAIN TROF INTO THE NORTHWEST/NRN US ROCKIES AND STARTING TO AMPLIFY INTO THE HIGH NORTHERN PLAINS TUES MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CMC BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE 00Z NAM SLOWED TO BECOME BETTER ALIGNED IN TIMING/PLACEMENT/STRENGTH OF THE LEAD SHORTWAVE ENERGY SHED INTO THE PACIFIC NORTHWEST SAT NIGHT INTO SUN...AND DEVELOPS INTO A CLOSED SYSTEM ACROSS THE NORTHERN PRAIRIE PROVIDENCES...ENOUGH TO NOT SEE MUCH DIFFERENCE WITH THIS SYSTEM UNTIL LATE MONDAY WELL INTO CANADA WHEN THE GFS IS A BIT SLOWER/WRAPPED UP THAN THE OTHER GUIDANCE RESULTING IN A SOUTHWEST DEEPER SURFACE REFLECTION. MODELS GENERALLY CONTINUE TO BE IN GOOD AGREEMENT AS THE MAIN LARGER SCALE BROAD WAVE TRANSLATES EAST WITH EMBEDDED SHORTWAVE ENERGY ENTERING WA/OR SUNDAY EVENING...SPREAD STARTS TO INCREASE AS THE WAVE AMPLIFIES ALONG THE US/CANADA BORDER WITH SLIGHT NEGATIVE TILT ORIENTATION ACROSS THE NORTHERN GREAT PLAINS AS ENERGY CARVES OUT THE BASE OF THE TROF. THE 00Z GFS/NAM CONTINUE TO SUPPORT THE FASTER 12Z UKMET AND CONTINUE TO TREND A BIT STRONGER MORE AMPLIFIED INTO NEB/KS BY THE END OF THE FORECAST TIME PERIOD. THE 12Z ECMWF/CMC BOTH EVOLVE THE WAVE SIMILARLY TO THE 00Z GFS/NAM AND 12Z UKMET THOUGH GENERALLY WEAKER. HOWEVER THE LARGEST DIFFERENCES SEEM TO BE RELATED UPSTREAM IN THE PLACEMENT/ORIENTATION OF THE ZONAL ONSHORE FLOW. THE 00Z UKMET/GFS/NAM ARE FOCUSED A BIT FURTHER NORTH AND AS SUCH THE WESTERN PORTION OF THE AMPLIFYING TROF IS ORIENTED MORE NW TO SE... WHILE THE ECMWF/CMC ARE OVERALL FLATTER HAVING THE FOCUS FURTHER SOUTH...CMC MORE SO THAN THE ECMWF...TO BE DISTINCTLY DIFFERENT IN THE MODEL HEIGHT SCATTER/SPAGHETTI PLOTS. THE ENSEMBLE SPREAD INCLUDING THE CMCE MEMBERS SUPPORTS A MIDDLE SOLUTION BETWEEN THE ECMWF/GFS...AS SUCH WILL PREFER TO REMOVE THE CMC ONLY GIVEN AGREEMENT IS ACTUALLY GOOD THROUGH DAY 3. CONFIDENCE IN A NON-CMC BLEND IS SLIGHTLY ABOVE AVERAGE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA