MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 135 AM EST SAT NOV 22 2014 VALID NOV 22/0000 UTC THRU NOV 25/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 00Z MODEL GUIDANCE ALONG WITH FINAL PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT ITS THEIR FORECASTS. ...INITIAL CLOSED LOW OVER NORTHWESTERN MX... ...EVENTUAL NEGATIVELY-TILTED TROF LIFTING INTO THE GREAT LAKES... ...RAPID CYCLOGENESIS OVER THE GREAT LAKES... ...POSITION OF MEAN TROF/ASSOCIATED COLD FRONT... FINAL PREFERENCE: BLEND OF THE 00Z UKMET/ECMWF/ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE A PRONOUNCED SHORTWAVE CURRENTLY EXITING THE DESERT SOUTHWEST WILL CONTINUE TO DIG WHILE CROSSING NORTHERN MX EVENTUALLY REACHING THE BIG BEND OF TX BY 23/0000Z. DIFFERENCES IN THE MODELS BECOME EVIDENT AS THIS SYSTEM MOVES THROUGH SOUTHEAST TX AND EVENTUALLY THROUGH THE LOWER MS VALLEY. AS WAS THE CASE YESTERDAY...THE 00Z NAM/CMC ARE SLOWER WITH THE EVOLUTION OF THIS SHORTWAVE. THE 00Z GFS/GFS-PARALLEL/UKMET/ECMWF OFFER REASONABLE REPRESENTATIONS OF THIS IMPULSE AS IT LIFTS ALONG THE MS RIVER AND EVENTUALLY INTO THE GREAT LAKES BY LATE SUNDAY. THERE ARE CONCERNS THAT THE 00Z GFS MAY BE TOO AGGRESSIVE WITH THE DEEPENING STAGE AND ALSO BECOMES TOO QUICK TO LIFT THE CYCLONE INTO ONTARIO. THIS STRENGTH DISCREPANCY APPEARS EVEN MORE RELEVANT AS A MAJORITY OF THE 00Z GUIDANCE HAVE TRENDED A BIT WEAKER. THE TIMING DIFFERENCE APPEARS TO EVOLVE FROM THE POSITION OF THE NORTHERN STREAM TROF CROSSING THE NORTHERN PLAINS/UPPER MIDWEST. THE 00Z GFS AND A MAJORITY OF THE 12Z GEFS MEMBERS SUGGEST A DEEPER/FASTER NORTHERN STREAM WHICH AIDS IN STRONGER LOW DEVELOPMENT DOWNSTREAM. NOT QUITE SOLD ON THIS SOLUTION...PARTICULARLY AS THE 0OZ GFS-PARALLEL SHOWS A SLIGHTLY WEAKER SYSTEM. THE MORE PROGRESSIVE NATURE OF THE 00Z GFS PUSHES THE COLD FRONT MUCH FARTHER EAST. THE 12Z ECMWF ENSEMBLE MEAN HAS SHOWN A GREAT DEAL OF STABILITY IN ITS PAST FEW MODEL CYCLES SO FEEL COMFORTABLE USING IT AS A BASE FOR THE FORECAST. THE 00Z ECMWF/UKMET AGREE REASONABLY WITH THIS ENSEMBLE MEAN WHILE THE 00Z UKMET DOES OFFER A DEEPER SOLUTION WHICH SEEMS MORE LIKELY GIVEN THE STRENGTH OF THE SHORTWAVE LIFTING INTO THE UPPER GREAT LAKES. THE SUGGESTED BLEND HERE IS A COMBINATION OF THE 00Z UKMET/ECMWF/ECMWF ENSEMBLE MEAN. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER