MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1234 PM EDT TUE APR 15 2014 VALID APR 15/1200 UTC THRU APR 19/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...CANADIAN TROUGH ADVANCING SOUTHEAST INTO THE NORTHERN PLAINS/UPPER MIDWEST/UPPER GREAT LAKES... PREFERENCE: NON-GEM CONSENSUS CONFIDENCE: AVERAGE MODEL SPREAD IS GRADUALLY DIMINISHING WITH REGARD TO THE NRN STREAM TROUGH THAT DIGS SOUTH FROM CNTRL CANADA AND TWD THE NRN PLAINS WED AND THURS. THE 00Z GEM APPEARS TO GRADUALLY BECOME A BIT OF A STRONGER OUTLIER WITH THE HEIGHT FALLS THAT PIVOT SEWD THROUGH THE PERIOD. HOWEVER...ALL OF THE MODELS LIKE THE IDEA OF AN ELONGATED W/E ORIENTED TROUGH THAT DIGS SEWD AND PIVOT ACROSS SRN CANADA WHILE CROSSING THROUGH THE NRN PLAINS/UPR MIDWEST AND ESP THE UPR GRT LAKES REGION WED THROUGH FRI. BASED ON THE LATEST GEFS MEAN AND ECENS MEAN FAVORING THE GLOBAL MODEL CONSENSUS...EXCEPT THE GEM...WILL PREFER A NON-GEM CONSENSUS. ...PACIFIC TROUGH DIGGING TOWARD THE CENTRAL ROCKIES/PLAINS/UPPER MIDWEST/GREAT LAKES... ...SURFACE LOW PRESSURE EVOLUTION THROUGH THE UPPER MIDWEST/UPPER GREAT LAKES... PREFERENCE: 00Z ECMWF CONFIDENCE: AVERAGE A PORTION OF THE SHORTWAVE TROUGH CURRENTLY CROSSING THE NORTHWEST WILL ADVANCE SEWD AND DIG TOWARD THE CNTRL ROCKIES BY WED...BEFORE THEN PROGRESSIVELY EJECTING EAST ACROSS THE PLAINS AND LIFTING NEWD TWD THE UPR MIDWEST BY EARLY THURS. ALL THE WHILE...LOW PRESSURE WILL BE REDEVELOPING IN THE LEE OF THE NRN ROCKIES AND MOVING INITIALLY SEWD AND THEN NEWD UP ACROSS THE PLAINS AND TWD THE UPR MIDWEST/UPR GRT LAKES REGION BY THURS. ON FRI...THIS LOW CENTER WILL BE DAMPENING OUT NEAR THE UPR GRT LAKES REGION AND SRN ONTARIO. THE 12Z NAM IS THE FASTEST SOLN SFC AND ALOFT WITH THE ENERGY AND IS GENERALLY THE STRONGEST. THE 00Z ECMWF/00Z UKMET AND 00Z GEM ARE THE SLOWEST...AND IT WAS NOTICED THAT THE 12Z GFS TRENDED A BIT SLOWER TWD THE 00Z ECMWF SOLN IN PARTICULAR. THE LATEST ECENS MEAN SUPPORTS THE NON-NCEP SOLNS...AND ALIGNS ITSELF WELL WITH THE ECMWF. THE LATEST GEFS MEAN SUPPORTS THE NAM IN PARTICULAR AND IS FASTER THAN THE CURRENT GFS. THE NAM SOLN SEEMS TO HANG ON TO THE SFC LOW LONGER OVER THE UPR GRT LAKES REGION/SRN ONTARIO INTO FRI...VS THE NON-NCEP CAMP. WILL PREFER THE 00Z ECMWF SOLN WHICH HAS EXCELLENT SUPPORT FROM THE LATEST ECENS MEAN AND OVERALL BETTER SUPPORT FROM THE GEM/UKMET SOLNS. DESPITE THE PREFERENCE FOR THE 00Z ECMWF FOR MASS FIELDS...THE ECMWF IS NOTABLY DRY AND LIKELY TOO DRY ACROSS PORTIONS OF THE UPR MIDWEST/UPR GRT LAKES. PLS CONSULT THE LATEST QPFHSD AND QPFPFD FOR DETAILS CONCERNING RAINFALL AND SNOWFALL POTENTIAL. ...NORTHERN TROUGH IMPACTING THE NORTHWEST THURS AND FRI... PREFERENCE: 00Z ECMWF/00Z UKMET COMPROMISE CONFIDENCE: AVERAGE THE MODELS SHOW RELATIVELY SIMILAR STRENGTH INITIALLY WITH THE NEXT PACIFIC SHORTWAVE EXPECTED TO ARRIVE THURS ACROSS THE NORTHWEST...BEFORE THEN MOVING DOWNSTREAM INTO THE NRN ROCKIES AND NRN HIGH PLAINS BY FRI. HOWEVER...THE 12Z NAM EVENTUALLY BECOMES A SLOWER/DEEPER OUTLIER. THE 00Z ECMWF EVENTUALLY LAGS THE GLOBAL MODEL CONSENSUS. THE 12Z GFS IS THE FASTEST SOLN AND FOCUSES MORE ENERGY OVER SWRN CANADA BY LATE FRI. THE 00Z GEM AND 00Z UKMET ARE A LITTLE SLOWER THAN THE GFS. THE LATEST GEFS MEAN SUGGESTS THE GFS IS TOO PROGRESSIVE AND TENDS TO FAVOR THE GEM/UKMET CAMP. THE LATEST ECENS MEAN IS VERY CLOSE TO THE ECMWF. BASED ON STRONGER MODEL CLUSTERING...AND ACCOUNTING FOR THE BROADER MODEL SPREAD...WILL FAVOR A BLEND OF THE ECMWF AND UKMET SOLNS. ...SOUTHERN STREAM UPPER TROUGH/POSSIBLE CLOSED LOW IMPACTING THE SOUTHWEST THURS/FRI... PREFERENCE: 12Z GFS/00Z ECMWF COMPROMISE CONFIDENCE: AVERAGE A SRN STREAM TROUGH OFFSHORE WILL BE DRAGGED EASTWARD BY AN INCREASINGLY ENERGETIC NRN STREAM FLOW IMPACTING THE NORTHWEST BY THURS AND FRI. THE SRN STREAM ENERGY WHICH MAY INCLUDE A WEAK CLOSED MID LVL LOW CENTER SHOULD ADVANCE INTO THE SOUTHWEST BY THE END OF THE PERIOD. THE 12Z NAM IS OVERALL THE STRONGEST SOLN WITH THIS SYS...WITH THE 00Z GEM THE WEAKEST. THE 00Z ECMWF/00Z UKMET AND THE 12Z GFS ALL SUPPORT THE IDEA OF A SRN STREAM TROUGH AND WEAK CLOSED LOW CENTER CROSSING SRN CA BY LATE THURS AND MOVING INTO THE DESERT SOUTHWEST BY FRI. THE LATEST GEFS MEAN AND ECENS MEAN BOTH STRONGLY SUPPORT THIS CLUSTER. WILL PREFER A GFS/ECMWF COMPROMISE ATTM. ...SOUTHERN STREAM TROUGH/SUBTROPICAL CONNECTION OVER FLORIDA BY FRI... PREFERENCE: 06Z GEFS MEAN/00Z ECENS MEAN COMPROMISE CONFIDENCE: BELOW AVERAGE THE MODELS ARE INDICATING A DISTINCT SRN STREAM TROUGH DIGGING INTO PORTIONS OF THE SOUTHEAST AND THE FL PENINSULA BY FRI...WITH A DISTINCT SUBTROPICAL MOISTURE CONNECTION. THE 00Z UKMET IS A STRONGER/SLOWER OUTLIER AND SUGGESTS A MUCH WETTER SOLN FOR THE FL PANHANDLE. THE 12Z NAM AND 12Z GFS FOCUS ENERGY FARTHER SOUTH INTO THE FL PENINSULA. THE 12Z GFS IS THE FASTEST SOLN. THE 00Z GEM AND 00Z ECMWF ARE SLOWER THAN THE GFS...BUT FASTER THAN THE UKMET. THE LATEST GEFS MEAN AND ECENS MEAN ARE NOT NEARLY AS STRONG AS THE SLOWER UKMET OR EVEN THE ECMWF FOR THAT MATTER...BUT ARE NOT AS PROGRESSIVE AS THE GFS. GIVEN THE OVERALL SPREAD OF THE GUIDANCE...WILL LEAN TWD THE ENSEMBLE MEANS ATTM. CONFIDENCE IS LIMITED. www.wpc.ncep.noaa.gov/html/model2.shtml... ORRISON