MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1254 PM EDT FRI JUN 24 2016 VALID JUN 24/1200 UTC THRU JUN 28/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 12Z NAM/GFS ALONG WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... ...INITIAL SHORTWAVE TRACKING THROUGH THE MID-ATLANTIC THIS AFTERNOON... ...REMNANT VORTICITY SPINNING WELL OFF THE NEW ENGLAND COAST... PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS/06Z GEFS MEAN FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE THE TRAILING PIECE OF SHORTWAVE ENERGY WITHIN A LARGER-SCALE TROUGH WILL PUSH OFF THE DELMARVA/NJ COAST BY THIS EVENING. AS THE SYSTEM CONTINUES TO PUSH AWAY FROM THE EASTERN SEABOARD...THE 12Z NAM HAS MAINTAINED A MORE ELONGATED/SOUTHWARD-EXTENDING TROUGH WHICH SUPPORTS AN INVERTED SURFACE TROUGH CLOSER TO THE CAROLINA COAST. NO DETERMINISTIC/ENSEMBLE SOLUTION SHOWS THIS IDEA AT THIS TIME. FURTHER OUT IN THE FORECAST PERIOD...SOME OF THE SHORTWAVE IS FORECAST TO PINCH OFF AND POSSIBLY DRIFT WESTWARD. THE 582-DM SPAGHETTI PLOTS THE PAST COUPLE OF MODEL CYCLES HAS INDICATED THE ECMWF ENSEMBLE MEMBERS ARE THE FARTHEST SOUTH/WEST OF THE OTHER MODELS. WILL PLAY IT A BIT MORE CONSERVATIVELY AND FAVOR THE 12Z GFS/06Z GEFS MEAN COMBINATION UNTIL OTHER SOLUTIONS JOIN THE ECMWF. ...COMPACT UPPER LOW PUSHING ACROSS THE NORTHERN ROCKIES SATURDAY MORNING... ...ASSOCIATED SURFACE CYCLONES/COLD FRONT... PRELIMINARY PREFERENCE: BLEND OF THE 12Z NAM/GFS WITH THE 00Z ECMWF FORECAST CONFIDENCE: AVERAGE WATER VAPOR IMAGERY DEPICTED A WELL ESTABLISHED UPPER TROUGH ADVANCING INTO EASTERN WA/NORTHERN ID. THIS SYSTEM IS FORECAST TO CONTINUE ACCELERATING EASTWARD GENERALLY STRADDLING THE INTERNATIONAL BORDER WITH CANADA. AS EARLY AS 24 TO 36 HOURS INTO THE FORECAST...SOME DISCERNIBLE DIFFERENCES ARE NOTED AS THE 00Z CMC REMAINS A SLOWER OUTLIER AS IT HAS BEEN FOR SOME TIME. SIMILARLY...THE 00Z UKMET CONTINUES TO BE DEEPER BOTH ALOFT AND AT THE SURFACE AS IT DEPICTS A 978-MB LOW OVER SOUTHERN MANITOBA BY 26/0600Z. BY SUNDAY MORNING...THE 12Z NAM/GFS ARE SIMILAR WITH TIMING WHILE THE 00Z ECMWF JUMPS A BIT AHEAD OF THIS CLUSTER. THIS IS A REVERSE OF ROLES BETWEEN THE GFS/ECMWF FROM YESTERDAY. ENSEMBLE SPAGHETTI PLOTS SHOW BOTH SCENARIOS BEING WELL WITHIN THE GENERAL SPREAD SO EACH SOLUTION APPEARS REASONABLE. PLAN ON SPLITTING THE DIFFERENCE BETWEEN THESE TWO CAMPS AND WILL RE-EVALUATE THE NEXT SET OF 12Z MODELS. ...TUTT CELL LIFTING ACROSS THE RIO GRANDE RIVER VALLEY... PRELIMINARY PREFERENCE: GENERAL MODEL COMPROMISE FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE A BROAD CIRCULATION CURRENTLY LIFTING OUT OF THE EASTERN MX WILL BEGIN TO MOVE ACROSS THE RIO GRANDE RIVER AND INTO THE BIG BEND AREA BY 25/1800Z. ALL MODELS AGREE THAT THE FEATURE SHOULD CONTINUE TO SHEAR WHILE MOVING NORTHWARD THROUGH A WEAKNESS IN A BROAD 594-DM RIDGE. THERE APPEARS TO BE CLOSE ENOUGH AGREEMENT HERE TO SUPPORT A GENERAL MODEL COMPROMISE. ...LOW AMPLITUDE SHORTWAVE APPROACHING THE PACIFIC NORTHWEST COAST BY LATE SUNDAY... PRELIMINARY PREFERENCE: A COMPROMISE BETWEEN THE 12Z NAM/GFS AND 00Z ECMWF FORECAST CONFIDENCE: AVERAGE AS THE PRIMARY BAND OF MID-LEVEL HEIGHT FALLS SLIDE AWAY FROM THE PACIFIC NORTHWEST...ANOTHER FEATURE EMERGES OFF THE EASTERN PACIFIC. BY SUNDAY AFTERNOON...AN ELONGATED/LOW-AMPLITUDE IMPULSE BEGINS TO APPROACH THE OR/WA COAST. LIKE THE PRECEDING DAY...THE 00Z CMC/UKMET ARE ON THE MUCH SLOWER SIDE OF THE SPREAD. SEE LITTLE REASON TO DIVERGE FROM THE CLUSTERING OF THE 12Z NAM/GFS AND 00Z ECMWF. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER