MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1116 AM EST MON FEB 08 2016 VALID FEB 08/1200 UTC THRU FEB 12/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES LOW PRESSURE FORMING OFF THE MID-ATLANTIC COAST TONIGHT/TUESDAY... PREFERENCE: 3-WAY BLEND 12Z NAM/12Z GFS/00Z ECMWF CONFIDENCE: AVERAGE SMALL-SCALE DIFFERENCES EMBEDDED WITHIN THE UPPER TROUGH COMBINED WITH MODESTLY STEEP MID LEVEL LAPSE RATES AND CLOSE PROXIMITY TO THE LINGERING MOISTURE GRADIENT OFF THE COAST ARE CONTRIBUTING TO CONTINUED MODEL SPREAD AND THEREFORE UNCERTAINTY WITH THE LOW TRACK...ITS DEPTH...AND EVEN TIMING. THE NAM HAS THE ADVANTAGE OF RECENT INITIALIZATION AND HIGH RESOLUTION BUT LIES NEAR THE STRONG EDGE OF THE GUIDANCE AND IS CLOSER TO THE COAST BY LATE TUESDAY COMPARED WITH MOST OTHER SOLUTIONS AND IS AGAINST RECENT TRENDS FOR A LOW MORE OFFSHORE. THE GFS HAS A LOW TRACK AND DEPTH NEAR THE CONSENSUS AND THEREFORE OFFERS ADVANTAGES BUT IS ALSO NEAR THE COLD EDGE OF THE GUIDANCE ALOFT CONTRIBUTING TO ASCENT AND MOISTURE SHIELDS THAT LIES NEAR THE HIGH END OF THE GUIDANCE. THE 06Z PARALLEL GFS IS MORE SUBDUED WITH THE COLDNESS ALOFT AND MAY AFFORD AN EVEN MORE RELIABLE SOLUTION. THE 00Z ECMWF IS NEAR THE SOUTHERN EDGE OF THE GUIDANCE BUT HAS SUPPORT FROM THE ITS OWN ENSEMBLE MEAN/SREF MEAN AND THE 00Z UKMET. THUS...WHILE ONLY MODESTLY SUPPORTED...WOULD PREFER TO SEE MORE RECENT GUIDANCE SUPPORT IT TO RELY UPON IT ENTIRELY. THUS...THE MOST PREFERRED APPROACH IS TO BLEND THE 12Z NAM/12Z GFS/00Z ECMWF AT THIS TIME. LONGWAVE TROUGH EXTENDING SOUTHWARD FROM THE GREAT LAKES TUE-WED... SURFACE TROUGH OVER NEW ENGLAND... PREFERENCE: NAM CONFIDENCE: AVERAGE THE NAM REPRESENTS THE MODEL CONSENSUS THROUGH THIS PERIOD...WITH THE 00Z ECMWF NEAR THE SOUTHERN EDGE OF THE GUIDANCE AND THE GFS NEAR THE COLD EDGE OF THE GUIDANCE THAT APPEARS TO TRANSFER TO A STRONGER SURFACE TROUGH OVER NEW ENGLAND ON THURSDAY THAN PREFERRED AT THIS TIME. LOW PRESSURE MOVING FROM MONTANA TO TEXAS WED-THU... PREFERENCE: NAM OR GFS CONFIDENCE: AVERAGE ALTHOUGH THE NAM IS A LITTLE STRONGER WITH THE LEE LOW FORMING DOWNWIND OF THE CANADIAN ROCKIES COMPARED TO THE GFS...THEY ARE CONCEPTUALLY SIMILAR AND STRONGER THAN THE 00Z ECMWF TRACKING SOUTHEASTWARD WITH A ZONE OF FRONTOGENESIS. GIVEN THEIR AGREEMENT AND MORE RECENT INITIALIZATION...THEY ARE MORE RECOMMENDED COMPARED TO THE ECMWF. SHORTWAVE TROUGH INFLUENCING THE PACIFIC NORTHWEST WED-THU... PREFERENCE: NAM OR ECMWF CONFIDENCE: ABOVE AVERAGE THE GFS LIES NEAR THE STRONG AND FAST EDGES OF THE GUIDANCE AND MAY BE SHOWING ITS OCCASIONAL FAST BIAS. GIVEN THE STRONG RIDGE ACROSS THE WEST AT THIS TIME...THE PREFERENCE IS FOR PERSISTENCE AND THEREFORE THE WEAKER NAM/ECMWF. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...