MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 233 PM EDT SUN MAR 27 2016 VALID MAR 27/1200 UTC THRU MAR 31/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...CONSOLIDATING LOW PRESSURE MOVING THROUGH THE OH VALLEY/NORTHEAST... PREFERENCE: BLEND OF THE 12Z UKMET AND 12Z ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE A WEAKENING SHORTWAVE AND ASSOCIATED SURFACE LOW OVER THE UPPER MIDWEST THIS MORNING WILL CONSOLIDATE AND ESSENTIALLY PHASE OVER THE NEXT 36 HOURS WITH THE STRONGER SHORTWAVE SEEN IN WV IMAGERY AND A RECENT AQUA-MODIS PASS OVER THE LOWER MO VALLEY. THIS WILL DRIVE AN AMPLIFYING UPPER TROUGH AND SURFACE LOW CENTER ACROSS THE LOWER GREAT LAKES REGION AND NORTHEAST THROUGH MON AND MON NIGHT. SECONDARY CYCLOGENESIS IS EXPECTED OFFSHORE THE MID-ATLANTIC BY EARLY MON...AND THIS LOW CENTER WILL BECOME THE DOMINANT LOW CENTER BY MON NIGHT AS IT APPROACHES AND MOVES INTO THE CANADIAN MARITIMES. THE 12Z NAM IN GENERAL APPEARS A TAD TOO SLOW WITH THE AMPLIFYING TROUGH AND SURFACE WAVE...WITH THE 12Z GFS APPEARING TO BE TOO DEEP. THE 12Z UKMET AND 12Z ECMWF ARE CLUSTERED RATHER CLOSE TO THE GFS WITH RESPECT TO TIMING BUT JUST NOT AS DEEP. THE 12Z CMC IS NOW GENERALLY CLOSE TO THE UKMET/CMC CAMP. WILL CONTINUE TO PREFER THE UKMET/ECMWF CLUSTER AT THIS TIME AS A COMPROMISE SOLUTION. ...DEEP CLOSED LOW DEVELOPING OVER THE WEST MON AND TUES... ...ENERGY/SURFACE LOW EJECTING OUT ACROSS THE CENTRAL PLAINS... ...ELONGATED TROUGH HANGING BACK TO THE SOUTHWEST BY MIDWEEK... PREFERENCE: BLEND OF THE 12Z GFS AND 12Z ECMWF CONFIDENCE: AVERAGE A PROGRESSIVE UPPER TROUGH AND ASSOCIATED FRONT CROSSING THE NORTHWEST TODAY WILL DIG VIGOROUSLY INTO THE INTERMOUNTAIN WEST MON AND TUES AS A STRONG UPSTREAM RIDGE/BLOCKING HIGH DEVELOPS OVER THE GULF OF AK AND INTO WESTERN BRITISH COLUMBIA. A DEEP CLOSED LOW EVOLVING OVER THE WESTERN U.S. WILL THEN GRADUALLY ADVANCE EAST TOWARD THE CENTRAL PLAINS ON WED...WITH THE FORWARD PROGRESSION OF THIS ENERGY EXPECTED TO BE IMPACTED HIGHLY BY THE ARRIVAL OF ADDITIONAL NORTHERN STREAM TROUGHING DIGGING SOUTHEAST ACROSS SOUTHERN CANADA AROUND THE SAME UPSTREAM RIDGE. MEANWHILE...ALL OF THE MODELS THEN SHOW STRONG AGREEMENT IN KEEPING AN ELONGATED TROUGH EXTENDING SOUTHWEST AWAY FROM THE CLOSED LOW BACK OVER THE SOUTHWEST U.S. AND UNDERNEATH THE STRONG AFOREMENTIONED RIDGING TO THE NORTH. THE TREND IN THE GUIDANCE INCLUDING THE GFS AND ECMWF IS FOR THIS INTRUSION OF ADDITIONAL NORTHERN STREAM ENERGY TO BE SOMEWHAT FLATTER/PROGRESSIVE AND MORE SHEARED ACROSS SOUTHERN CANADA...WHICH WOULD ENCOURAGE MORE SEPARATION FROM THE CLOSED LOW MOVING INTO THE CENTRAL PLAINS...AND THUS A SOMEWHAT LESS PROGRESSIVE SOLUTION WITH THE ENERGY EJECTING OUT OF THE WEST AND INTO THE PLAINS OVERALL. THE GUIDANCE IS RELATIVELY WELL CLUSTERED WITH THE HEIGHT FALLS EVOLVING OVER THE WEST THROUGH 60 HOURS. THEREAFTER...THERE REMAINS SOME SPREAD BUT THERE ARE CONVERGING TRENDS WITH THE ECMWF TRENDING A TAD MORE PROGRESSIVE AND THE GFS A BIT SLOWER. THE 12Z GFS AND 12Z ECMWF ACTUALLY MAKE FOR A NICE COMPROMISE SOLUTION AT THIS POINT ALOFT AND AT THE SURFACE WITH THE LOW CENTER. THE 12Z NAM AND 12Z CMC ARE ON THE SOMEWHAT SLOWER SIDE OF THE MODEL SPREAD NOW...AND THE 12Z UKMET A LITTLE FASTER AT LEAST REGARDING THE UPPER TROUGH PROGRESSION. THE 12Z UKMET SURFACE LOW ALSO LOOKS TO BE A TAD SOUTH OF THE CONSENSUS. THE 12Z GEFS MEAN STRONGLY SUPPORTS THE OPERATIONAL GFS/ECMWF CAMP...AND SO A BLEND OF THESE TWO SOLUTIONS WILL BE PREFERRED AT THIS POINT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON