MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1259 AM EST MON JAN 11 2016 VALID JAN 11/0000 UTC THRU JAN 14/1200 UTC ..SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z NAM/GFS EVALUATION ALONG WITH PRELIMINARY PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SERIES OF NRN STREAM IMPULSES TRAVERSING THE GREAT LAKES REGION SURFACE LOW CROSSING THE GREAT LAKES TUE...REDEVELOPING OFF NEW ENGLAND LATE TUE NIGHT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z NAM / 12Z ECMWF COMPROMISE THROUGH 00Z/13 00Z GFS / 12Z ECMWF COMPROMISE FROM 00Z/13-12Z/14 CONFIDENCE: AVERAGE WHILE THE MODELS HAVE BEEN WOBBLING BACK AND FORTH WITH THE TIMING/STRENGTH OF THE SHORTWAVE TO PASS OVER THE GREAT LAKES ON TUE...THE 00Z GFS IS FASTER THAN THE REMAINING TIGHT DETERMINISTIC/ENSEMBLE CONSENSUS. HOWEVER...BY THE TIME A LOW REDEVELOPS OVER ERN MAINE TUE NIGHT...THE 12Z ECMWF AND ITS ENSEMBLES APPEAR TO BE ON THE SLOW SIDE TO LIFT THIS WAVE NWD. A BLEND OF THE 00Z GFS/12Z ECMWF APPEARS BEST WITH THE REDEVELOPED SURFACE LOW IMPACTING NEW ENGLAND EARLY ON WED COMPARED TO THE LATEST ENSEMBLE LOW PLOTS...WHILE THE 00Z NAM APPEARS TO DEVELOP THE LOW TOO FAR OFFSHORE. SHORTWAVE SHEARING EASTWARD ACROSS THE SRN U.S. MON/TUE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW SIMILARLY WITH THIS FEATURE. SHORTWAVE TRACKING FROM NWRN MEXICO WED MORNING TO THE LOWER RIO GRANDE VALLEY THU MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 00Z GFS...12Z ECMWF...12Z UKMET CONSENSUS CONFIDENCE: AVERAGE MUCH BETTER ENSEMBLE AGREEMENT EXISTS WITH THIS FEATURE TODAY COMPARED TO PREVIOUS CYCLES. THE GFS/ECMWF/UKMET ARE IN THE MIDDLE OF THE LATEST SPREAD...WITH THE 00Z NAM FASTER...AND 12Z CMC SLOWEST. SHORTWAVE REACHING THE PACIFIC NORTHWEST THIS MORNING OPEN WAVE MOVING TOWARD THE GREAT PLAINS BY MID-WEEK ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF CONFIDENCE: AVERAGE THERE ARE VERY MINOR DIFFERENCES WITH THE SHORTWAVE AS IT MOVES ACROSS THE PACIFIC NORTHWEST COAST...BUT THESE DIFFERENCES AMPLIFY AS THE WAVE MOVES PAST A WRN RIDGE INTO THE PLAINS. GIVEN THE 12Z CMC IS ON THE SOUTH SIDE OF THE MODEL SPREAD AND GOES UNSUPPORTED...THE CMC APPEARS UNLIKELY. THE 00Z NAM IS ON THE OTHER EXTREME WITH A FLATTER/SLOWER WAVE. THE 00Z GFS AND 12Z ECMWF ARE CLOSEST TO THE MIDDLE WITH TWO SMALLER SCALE EMBEDDED VORTICITY MAXIMA POSSIBLE GIVEN THE LATEST AVAILABLE GUIDANCE. DEEP UPPER TROUGH REACHING THE WEST COAST BY WEDNESDAY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF THE 00Z NAM/00Z GFS/12Z ECMWF CONFIDENCE: SLIGHTLY BELOW AVERAGE THE 12Z CMC STANDS OUT THE MOST OF THE LATEST GUIDANCE WITH A WEAKER TROUGH ENTERING THE WESTERN U.S. AND SIMILARLY LESS AMPLIFIED FLOW DOWNSTREAM. THE REMAINING MODELS SHOW SOME TIMING/AMPLITUDE DIFFERENCES...WITH THE 12Z UKMET THE NEXT FLATTEST/FASTEST MODEL. THOUGH THE 12Z ECMWF IS A BIT AHEAD OF THE 00Z NAM/GFS...A BLEND OF THE 3 MODELS APPEARS TO OFFER THE BEST COMPROMISE AT THIS TIME...AND RESIDES CLOSEST TO THE LATEST ENSEMBLE MEANS. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... OTTO