MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 252 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/GFS/UKMET/GEM AND ECMWF ...CANADIAN TROUGH ADVANCING SOUTHEAST INTO THE NORTHERN PLAINS/UPPER MIDWEST/GREAT LAKES... PREFERENCE: 12Z UKMET/12Z GEM/12Z ECMWF COMPROMISE CONFIDENCE: AVERAGE MODEL SPREAD IS GRADUALLY DIMINISHING WITH REGARD TO THE W/E ORIENTED NRN STREAM TROUGH THAT DIGS SOUTH FROM CNTRL CANADA ON WED AND PIVOTS ACROSS SRN CANADA AND ADJACENT AREAS OF THE NRN PLAINS/UPR MIDWEST AND ESP THE GRT LAKES REGION THURS AND FRI. THE 12Z NAM AND 12Z GFS DIG THEIR HEIGHT FALLS A LITTLE MORE AGGRESSIVELY TO THE SOUTHEAST INTO THE UPR MIDWEST AND UPR GRT LAKES REGION BY FRI...WITH THE 12Z UKMET/12Z GEM AND 12Z ECMWF A LITTLE SLOWER TO DO SO AND FOCUSING THE BULK OF THEIR ENERGY STILL UP ACROSS SRN CANADA. BASED ON THE LATEST GEFS MEAN AND ECENS MEAN FAVORING THE NON-NCEP MODELS AND SUGGESTING THAT THE NAM/GFS CAMP DIGS ENERGY A LITTLE TOO FAR SOUTH BY FRI OVER THE GRT LAKES REGION...WILL FAVOR A NON-NCEP 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: 12Z 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 12Z UKMET AND 12Z GEM ARE THE SLOWEST SOLNS...WITH THE 12Z GFS AND 12Z ECMWF SPLITTING THE DIFF BETWEEN THE FASTER AND SLOWER CAMPS. THE LATEST ECENS MEAN SUPPORTS THE 12Z ECMWF VERY STRONGLY...WITH THE LATEST GEFS MEAN JUST A TAD SLOWER THAN THE GFS. BASED ON THE LATEST TRENDS AND MODEL SPREAD...A SOLN TWD THE 12Z ECMWF WILL BE PREFERRED FOR MASS FIELDS. HOWEVER...DESPITE THAT...THE ECMWF IS NOTABLY DRY AND LIKELY TOO DRY ACROSS PORTIONS OF THE UPR MIDWEST/UPR GRT LAKES AS COMPARED TO THE REMAINING MODELS. PLS CONSULT THE LATEST QPFHSD AND QPFPFD FOR DETAILS CONCERNING RAINFALL AND SNOWFALL POTENTIAL. ...NORTHERN TROUGH IMPACTING THE NORTHWEST THURS AND FRI... PREFERENCE: 12Z UKMET/12Z GEM/12Z ECMWF 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 SLOW OUTLIER. THE 12Z ECMWF/12Z UKMET AND 12Z GEM ALL CLUSTER RATHER WELL WITH THE ENERGY ATTEMPTING TO AMPLIFY A BIT OVER THE NRN ROCKIES/NRN HIGH PLAINS BY FRI AND ARE A BIT FASTER THAN THE 12Z NAM. THE 12Z GFS THOUGH IS THE FASTEST MODEL AND APPEARS A LITTLE TOO QUICK. THE LATEST GEFS MEAN WAS A TAD SLOWER THAN THE GFS...AND THE LATEST ECENS MEAN SUPPORTS A SLOWER SOLN AWAY FROM THE GFS. WILL PREFER A NON-NCEP CONSENSUS ATTM BASED ON STRONGER MODEL CLUSTERING. ...SOUTHERN STREAM UPPER TROUGH/POSSIBLE CLOSED LOW IMPACTING THE SOUTHWEST THURS/FRI... PREFERENCE: 12Z GFS/12Z 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. MOST OF THE MODELS WITH THE 12Z CYCLE HAVE TRENDED A BIT STRONGER. THE 12Z GEM IS THE STRONGEST SOLN...WITH THE 12Z UKMET NOW THE WEAKEST. THE 12Z NAM IS THE FASTEST. MEANWHILE...THE 12Z GFS AND 12Z ECMWF ACTUALLY CLUSTER VERY WELL ALOFT AND ARE COMPARABLE TO THE 12Z GEM FOR TIMING OF THE HEIGHT FALLS. THE LATEST GEFS MEAN AND ECENS MEAN BOTH STRONGLY SUPPORT THE GFS/ECMWF CAMP...AND SO THESE SOLNS WILL BE PREFERRED. ...SOUTHERN STREAM TROUGH/SUBTROPICAL CONNECTION OVER FLORIDA BY FRI... PREFERENCE: 12Z UKMET/12Z GEM/12Z ECMWF 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 12Z UKMET/12Z GEM AND 12Z ECMWF HAVE ALL TRENDED TWD EACH OTHER ON A SOLN THAT IS FAIRLY AMPLIFIED AND CERTAINLY WETTER FOR THE ERN GULF COAST REGION AND FL FOR THURS NIGHT/FRI. THE 12Z NAM AND ESP THE 12Z GFS ARE MORE PROGRESSIVE AND SOMEWHAT WEAKER/BROADER WITH THE TROUGHING. THE LATEST GEFS MEAN AND ECENS MEAN SUPPORT A SOMEWHAT WEAKER SOLN...BUT BASED ON THE CLUSTERING AND TRENDS OF THE NON-NCEP MODELS...WILL PREFER A UKMET/GEM/ECMWF COMPROMISE. CONFIDENCE IS LIMITED...BUT IN ANY CASE...ALL OF THE MODELS SUPPORT A WELL-ESTABLISHED SUBTROPICAL MOISTURE/JET CONNECTION. PLS CONSULT THE LATEST QPFPFD FOR MORE DETAILS ON THE RAINFALL POTENTIAL. www.wpc.ncep.noaa.gov/html/model2.shtml... ORRISON