MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1229 AM EDT THU JUN 05 2014 VALID JUN 05/0000 UTC THRU JUN 08/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ================================================== 00Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES ================================================== NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. ================================================== ...CLOSED MID LEVEL SYSTEM OVER THE NORTHEAST AND ITS ASSOCIATED SURFACE LOW... PREFERENCE: BLEND OF 12Z UKMET/CANADIAN CONFIDENCE: BELOW AVERAGE THERE WAS FAIRLY GOOD CONTINUITY WITH REGARD TO THE 00Z NAM...WITH BOTH ITS MID LEVEL CLOSED SYSTEM AND THE TRACK O THE SURFACE LOW. THE 00Z GFS WAS A BIT FASTER AND FURTHER EAST WITH ITS MID LEVEL SYSTEM AND SURFACE LOW TRACK...AND AGAIN APPEARS TO BE THE EASTERN OUTLIER WITH RESPECT TO THE SURFACE LOW TRACK. THE 12Z ECMWF AGAIN LOOKS TO BE A WESTERN OUTLIER WITH THE TRACK OF THE SURFACE LOW...AS ITS ENSEMBLE MEAN IS EAST OF THAT POSITION. AT THIS POINT...A BLEND OF THE 12Z UKMET/CMC LOOKS BEST WITH RESPECT TO THE SURFACE LOW TRACK (WHICH IS JUST EAST OF THE ECMWF ENSEMBLE MEAN)... AND REMAINS THE PREFERRED BLEND. ...SHORT WAVES AFFECTING CENTRAL PLAINS/MIDWEST/GREAT LAKES... PREFERENCE: BLEND OF 00Z/12Z OPERATIONAL MODELS CONFIDENCE: BELOW AVERAGE THERE ARE TWO MAIN SHORT WAVES IN THE FLOW. THE FIRST CROSSES THE MIDWEST INTO THU...AND WHILE THE 00Z NAM MAY BE A TAD FAST WITH THIS FEATURE...IT IS WITHIN THE ENVELOPE OF SOLUTIONS...AS IS THE 00Z GFS. SO...WITH THIS FEATURE...A MULTI MODEL BLEND SHOULD OFFER THE BEST SOLUTION. THE SECOND SHORT WAVE EMERGES FROM THE ROCKIES AND CENTRAL PLAINS FRI INTO SAT. THIS SHORT WAVE MAY BE THE MORE IMPORTANT FEATURE...AS IT SPINS UP A SURFACE LOW ON A LOW LEVEL FRONT THAT STRETCHES FROM THE SOUTHERN PLAINS INTO THE MIDWEST. THERE IS A FAIR AMOUNT OF SPREAD CONCERNING THE TIMING OF THE SHORT WAVE...WITH THE 00Z NAM/12Z ECMWF SOLUTIONS SHOWING THE FASTEST MOTION...AND A 00Z GFS/12Z CMC BLEND REPRESENTING THE MEDIAN SOLUTION. BECAUSE OF THE SHORT WAVE TIMING...THERE IS SPREAD IN THE SURFACE LOW POSITION. THE 12Z ECMWF MAY BE TOO FAR EAST AND TOO STRONG...BASED ON ITS SHORT WAVE POSITION...WHILE THE 00Z GFS LOOKS TOO SLOW AND SOUTHWEST WITH THE SURFACE LOW (LIKE THE GEFS MEAN). THE 12Z CMC AND 00Z NAM POSITIONS LOOKS LIKE A COMPROMISE POSITION FOR THE LOW BY 12Z SUN. GIVEN THE AMOUNT OF MODEL SPREAD...AND THE IMPLICATIONS FOR HEAVY RAIN IN THE CENTRAL PLAINS/MIDWEST...A BLEND MAY END UP BEING THE BEST SOLUTION UNTIL THERE IS BETTER MODEL CONSENSUS. ...NORTHERN ROCKIES/PLAINS... PREFERENCE: BLEND OF 12Z ECMWF/UKMET/CMC CONFIDENCE: AVERAGE 00Z NAM AND 00Z GFS APPEAR TO BE FASTER THAN THE CONSENSUS WITH BOTH THE MID LEVEL TROUGH AND THE SURFACE FRONTAL POSITION BY DAY 3. THERE IS BETTER MODEL AGREEMENT WITH RESPECT TO THE SURFACE FRONT FROM THE 12Z ECMWF/UKMET/CMC...AS THE MID LEVEL TROUGH LINES UP BETTER. ...SOUTHWEST... PREFERENCE: BLEND OF OPERATIONAL MODELS CONFIDENCE: AVERAGE THERE CONTINUES TO BE A FAIR AMOUNT OF MODEL SPREAD IN THE MID LEVEL TROUGH POSITION ACROSS THIS REGION. BOTH THE 00Z NAM AND GFS ARE WITHIN THE SPREAD WITH RESPECT TO THE MID LEVEL TROUGH POSITION...THOUGH THE 00Z NAM IS DEEPER WITH THE MEAN TROUGH POSITION OVER THE FOUR CORNERS REGION. THE 12Z UKMET APPEARS TO BE DEEPER AND A BIT FURTHER WEST THE TROUGH POSITION THAN THE CONSENSUS BY THE END OF DAY 3...BUT GIVEN THE SPREAD...IT IS CLOSE ENOUGH TO THE CONSENSUS TO INCLUDE IN THE BLEND. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... HAYES