MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1139 AM EST MON NOV 16 2015 VALID NOV 16/1200 UTC THRU NOV 20/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE MOVING THROUGH THE MID MS VALLEY TODAY... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE A SHORTWAVE EMBEDDED WITHIN THE SUBTROPICAL JET OVER THE MID MS VALLEY IS EXPECTED TO GRADUALLY SHEAR OUT DOWNSTREAM OVER THE OH VALLEY TONIGHT. THE MODELS ARE IN GOOD AGREEMENT WITH THE MASS FIELD DETAILS OF THIS...SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED. ...DEEP UPPER TROUGH/CLOSED CROSSING THE FOUR CORNERS/PLAINS/MIDWEST... ...INTENSIFYING SURFACE LOW OVER THE CENTRAL PLAINS LIFTING TO THE UPPER MIDWEST... PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 36 HOURS NON-NAM CONSENSUS...AFTER 36 HOURS CONFIDENCE: SLIGHTLY ABOVE AVERAGE A STRONG UPPER TROUGH/CLOSED LOW MOVING INTO THE FOUR CORNERS REGION WILL EJECT EAST OUT INTO THE CENTRAL AND SOUTHERN PLAINS LATE TONIGHT AND TUESDAY. THEREAFTER...THE SYSTEM WILL LIFT NORTHEAST ACROSS THE MIDWEST AND UPPER GREAT LAKES REGION THROUGH WED. THE STRONG HEIGHT FALLS ARE ALREADY DRIVING CYCLOGENESIS IN THE LEE OF THE ROCKIES OVER EASTERN CO AND THIS LOW CENTER WILL DEEPEN EASTWARD ACROSS WESTERN KS EARLY TUES BEFORE LIFTING NORTHEAST THROUGH THE UPPER MIDWEST ON WED. THE GUIDANCE IS IN GOOD AGREEMENT WITH THEIR MASS FIELDS THROUGH ABOUT 36 HOURS...BUT THEREAFTER THE 12Z NAM IS SEEN AS GENERALLY BEING TOO WEAK WITH ITS LOW CENTER AS IT LIFTS TOWARD THE UPPER MIDWEST. THE 12Z NAM ALSO BECOMES SLOW TO EJECT ITS MID LEVEL LOW CENTER OUT OF THE CENTRAL PLAINS AND THROUGH THE MIDWEST. THE REMAINING GLOBAL MODELS EXHIBIT SOME MINOR TIMING AND DEPTH DIFFERENCES...BUT ARE IN REASONABLY GOOD AGREEMENT. A GENERAL MODEL COMPROMISE WILL BE PREFERRED THROUGH 36 HOURS...WITH A NON-NAM CONSENSUS THEREAFTER. ...UPPER TROUGH/SURFACE LOW INITIALLY OVER THE NORTHERN HIGH PLAINS... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE AN UPPER TROUGH CURRENTLY MOVING ACROSS PARTS OF THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS WILL ADVANCE EAST TODAY AND TONIGHT ALONG WITH AN AREA OF LOW PRESSURE. THIS LOW WILL WEAKEN AS IT MOVES FROM MT INTO ND TONIGHT...BUT A WELL-DEFINED FRONTAL ZONE WILL REMAIN INTACT AND MOVE OUT ACROSS THE NORTHERN PLAINS THROUGH TUES. A GENERAL MODEL COMPROMISE WILL BE PREFERRED WITH THIS SYSTEM. ...STRONG WARM FRONT/ONSHORE FLOW ARRIVING IN THE PACIFIC NORTHWEST TODAY AND TONIGHT... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW VERY GOOD AGREEMENT IN BRINGING A VERY PROGRESSIVE WARM FRONT AND SURGE OF STRONG ONSHORE FLOW INTO THE PACIFIC NORTHWEST BY LATER TODAY AND TONIGHT. THERE IS FAIRLY MINIMAL SPREAD WITH THE TIMING OF THE FRONT...SO WILL GO WITH A GENERAL MODEL COMPROMISE WITH THIS. ...SECONDARY FRONT/ONSHORE FLOW BURST IMPACTING SOUTHWEST CANADA/PACIFIC NORTHWEST ON TUES... ...STRONG HEIGHT FALLS OVER THE NORTHERN PLAINS/UPPER MS VALLEY BY WED/THURS... ...COLD FRONT SURGING ACROSS THE GREAT LAKES/MS VALLEY BY THURS... PREFERENCE: BLEND OF THE 00Z UKMET AND 00Z ECMWF CONFIDENCE: AVERAGE THE MODELS DEPICT YET ANOTHER IN A SERIES OF SHORTWAVE IMPULSES/PROGRESSIVE FRONTS AND SURGES OF STRONG ONSHORE FLOW INTO SOUTHWEST CANADA AND THE PACIFIC NORTHWEST ARRIVING ON TUES. THE 12Z NAM GRADUALLY BECOMES A BIT SLOW WITH THE FRONT AS IT CROSSES THE REGION AND MOVES INTO THE INTERMOUNTAIN WEST. THE GUIDANCE THOUGH SHOWS THE ASSOCIATED SHORTWAVE/JET ENERGY AMPLIFYING SHARPLY OVER THE NORTHERN PLAINS AND UPPER MS VALLEY WED AND THURS. THE 12Z GFS AGAIN IS MORE AGGRESSIVE WITH THE HEIGHT FALLS AND SHOWS A STRONGER SURFACE CENTER OVER SOUTHERN CANADA VERSUS THE GLOBAL MODEL CONSENSUS. THE GFS ALSO SHOWS THE STRONG SECONDARY COLD FRONT BECOMING A LITTLE MORE PROGRESSIVE THAN THE REMAINING GUIDANCE BY THURS AS IT CROSSES THROUGH THE MIDWEST AND GREAT LAKES. THE NAM REMAINS SLOWER WITH THE FRONT WITH THE NON-NCEP MODELS CLUSTERED IN BETWEEN. STRONG MODEL CLUSTERING OVERALL FAVORS A BLEND OF THE 00Z ECMWF AND 00Z UKMET...AND THIS WILL BE THE PREFERENCE. ...UPPER TROUGH CLIPPING THE NORTHEAST THROUGH TONIGHT... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE GUIDANCE DEPICTS AN UPPER TROUGH DROPPING SOUTHEAST FROM QUEBEC AND CLIPPING NORTHERN NEW ENGLAND TODAY AND TONIGHT. THE MODELS ARE IN GOOD AGREEMENT AND THUS A GENERAL MODEL COMPROMISE WILL BE PREFERRED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON