MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1108 AM EST SUN NOV 22 2015 VALID NOV 22/1200 UTC THRU NOV 26/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH FORECAST PREFERENCE AND CONFIDENCE EAST COAST FRONTAL ZONE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE OVERALL THE ENSEMBLE SUITE AND OPERATIONAL DETERMINISTIC RUNS ARE WELL AGREED UPON POSITION AND TIMING OF THE FRONTAL ZONE AND MAIN SURFACE WAVE WITH THE OPERATIONAL MODELS AND ENSEMBLE MEANS. SMALL DIFFERENCES IN TIMING WITH THE NAM/ECMWF/UKMET A BIT FASTER THAN THE GFS/CMC BUT ARE ALL WITHIN THE OVERALL TROUGH/LOW PRESSURE ENVELOPE...WITH OTHER MODELS SUCH AS THE 12Z NAM AND 00Z UKMET PLACING VERY WEAK SECONDARY AND TERTIARY CLOSED CENTERS FURTHER SOUTH ALONG THE FRONTAL ZONE...WITH NO MODEL DISTINCTLY FAVORED OR SUPERIOR AND OVERALL BLEND SHOULD SUFFICE WITH ABOVE AVERAGE CONFIDENCE. SHORTWAVE TROUGH WEAKENING AS IT APPROACHES GREAT LAKES MONDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE STRONG DETERMINISTIC AND ENSEMBLE MODEL AGREEMENT EXISTS WITH POSITION/TRACK AND INTENSITY OF THE CLIPPER SYSTEM DROPPING SOUTHEAST TOWARD THE GREAT LAKES ON MONDAY BEFORE IT DEVOLVES INTO TUESDAY. OVERALL MODEL AGREEMENT IS STRONG ENOUGH TO SUPPORT AN OPERATIONAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE. PACIFIC CLOSED LOW COMES ASHORE IN CA ON MONDAY...RAPIDLY SHIFTS EAST AND SHEARS OUT INTO THE GREAT PLAINS WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: OPERATIONAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE THE MODEL TRENDS CONTINUE TO SHIFT INTO MUCH STRONGER AGREEMENT IN TIMING/STRENGTH WITH THE EVOLUTION OF THE UPPER LOW THAT IS CURRENTLY NEAR 40N 133W AND RAPIDLY MOVES EAST ACROSS THE ROCKIES WITH LITTLE FANFARE QPF-WISE DUE TO THE DRY ANTECEDENT CONDITIONS...BUT STILL IMPACTS SENSIBLE WEATHER/MASS FIELDS...EVENTUALLY DRAWING SOME MOISTURE NORTH OUT THE GULF FOR THURSDAY ACROSS THE GREAT PLAINS. THE NAM WAS THE LAST OUTLIER FAVORING A NORTHERLY TRACK AS THE WAVE WEAKENED ACROSS KS...BUT NOW AS JOINED THE 12Z GFS AND 00Z UKMET/ECMWF/CMC. THIS AGREEMENT ACTUALLY MAKES THE 06Z GEFS THE FASTEST OF THE ENSEMBLE AND OPERATIONAL SUITE. UNCHARACTERISTICALLY THE 00Z UKMET IS THE SLOWEST OF THE OPERATIONAL MODELS...BUT STILL WITHIN THE SUITE TO SUPPORT AN OPERATIONAL MODEL BLEND AS PREFERENCE. WITH ALL MEMBERS ALIGNED CONFIDENCES IS ABOVE AVERAGE. UPPER LOW CLOSING OFF THE NORTHWEST PACIFIC COAST TUESDAY AND DROPPING INTO THE GREAT BASIN WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 12Z GFS/NAM AND 00Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE ENSEMBLE SPAGHETTI PLOT SHOW FAIRLY STRONG AGREEMENT THROUGH MUCH OF THE EVOLUTION OF THE TROF CUTTING OFF INTO THE CLOSED LOW EVENTUALLY MOVING SOUTH-SOUTHEAST INTO THE GREAT BASIN. THE 00Z UKMET IS FIRST TO BREAK FROM THE STRONG CONSENSUS BY 25/00Z...THIS IS FOLLOWED BY THE 00Z CMC BECOMING FAST AS WELL. THE 12Z NAM IS A BIT STRONGER WITH INCREASED AMPLIFICATION OF AN EMBEDDED SHORTWAVE SWINGING THROUGH THE WESTERN SEMICIRCLE OF THE UPPER LOW ON WED ACROSS CENTRAL CA. THIS STRONGER MORE CONSOLIDATED WAVE MAKES IT THE SLOWEST COMPARED TO THE 12Z GFS AND 00Z ECMWF WHICH HAVE SIMILAR S/W TROUGHING. THE 00Z ECENS MEAN AND 06Z GEFS GENERALLY WASH OUT THIS EMBEDDED SHORTWAVE TROF...LIKELY DUE TO THE SLIGHT DIFFERENCES IN THE TIMING OVERALL...BUT STILL SUPPORT THE OVERALL EVOLUTION OF THE 12Z NAM/GFS AND 00Z ECMWF. AS SUCH A BLEND OF THE 12Z GFS/NAM AND 00Z ECMWF IS PREFERRED AT SLIGHTLY ABOVE AVERAGE CONFIDENCE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA