MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1255 PM EDT THU JUN 23 2016 VALID JUN 23/1200 UTC THRU JUN 27/0000 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... ...BROAD UPPER TROUGH LIFTING OUT OF THE NORTHEASTERN U.S... ...PARENT SURFACE BOUNDARY SINKING DOWN INTO THE SOUTHEAST... PRELIMINARY PREFERENCE: NON-12Z NAM MODEL COMPROMISE FORECAST CONFIDENCE: AVERAGE AN EXPANSIVE TROUGH OVER THE NORTHEASTERN SECTOR OF THE CONUS SHOULD GRADUALLY BEGIN TO EXIT WHILE RESIDUAL SHORTWAVE ENERGY TRAVERSES THROUGH THE MID-ATLANTIC FRIDAY AFTERNOON. ALL MODELS SHOW THIS FEATURE ELONGATED OFF THE EASTERN SEABOARD WHILE A SURFACE FRONTAL ZONE STALLS ACROSS THE SOUTHEASTERN U.S. THE 12Z NAM SEEMS TO BE FAR TOO NORTH WITH THE FRONTAL PLACEMENT OFF THE CAROLINAS RELATIVE TO OTHER CLUSTERED GUIDANCE. A NON-12Z NAM MODEL COMPROMISE APPEARS SUFFICIENT HERE. ...DEEP CLOSED LOW TRACKING FROM THE PACIFIC NORTHWEST TO SOUTHERN MANITOBA... ...ASSOCIATED SURFACE CYCLONES/COLD FRONT... PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS WITH THE 00Z ECMWF/ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE A COMPACT UPPER LOW WILL BE THE MAIN FEATURE OF INTEREST AS IT EJECTS EASTWARD TOWARD THE NORTHERN TIER. SOME NOTABLE DIFFERENCES BECOME EVIDENT BY DAY 2 AS THE 12Z NAM ENDS UP ON THE SLOWER SIDE OF THE SPREAD. MEANWHILE...MULTIPLE RUNS OF THE UKMET HAVE EXHIBITED A MUCH MORE DEVELOPED UPPER/SURFACE SOLUTION WHILE ALSO BEING MORE AGGRESSIVE WITH SOME OF THE VORTICITY MAXIMA ROUNDING THE BASE OF THE TROUGH. THE 06Z GFS HAD BEEN A QUICK OUTLIER BUT THE MORE RECENT RUN MADE SOME SLOWER ADJUSTMENTS. THE 12Z GFS ENDS UP CLOSER TO THE 00Z ECMWF/ECMWF ENSEMBLE MEAN. WPC RECOMMENDS SUCH A SOLUTION WITH THE ENSEMBLE MEAN INCORPORATED TO HANDLE THE INCREASED SPREAD. ...POSSIBLE MID-LEVEL IMPULSE MOVING ACROSS THE BIG BEND OF TX BY LATE SATURDAY... PRELIMINARY PREFERENCE: GENERAL MODEL COMPROMISE FORECAST CONFIDENCE: ABOVE AVERAGE A BROAD CIRCULATION CURRENTLY OVER SOUTHEASTERN MX WILL GRADUALLY LIFT NORTHWARD TOWARD THE RIO GRANDE RIVER. MODELS SHOW THIS FEATURE SHEARING AS IT BATTLES WITH A WEST-EAST ORIENTED RIDGE. THERE IS A GENERAL CONSENSUS THAT THE SHEARING SYSTEM SHOULD CROSS THE BIG BEND OF TX BY 26/0000Z WITH LOWER END SPREAD NOTED. WHAT REMAINS OF THIS WAVE WILL MIGRATE NORTHWARD ACROSS SOUTHWEST TX WITHIN THE WEAKNESS IN THE EXPANSIVE 594-DM RIDGE. GIVEN REASONABLE MODEL AGREEMENT...A GENERAL MODEL COMPROMISE IS WARRANTED. ...WEAK SHORTWAVE APPROACHING THE OR COAST BY LATE IN THE WEEKEND... PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF FORECAST CONFIDENCE: AVERAGE TOWARD THE END OF THE PERIOD...A LOW AMPLITUDE SHORTWAVE ENTERS THE PICTURE AS IT APPROACHES THE OR COAST BY THE LATTER HALF OF THE WEEKEND. TIMING DIFFERENCES ARE EVIDENT WITH THE 12Z NAM LEADING THE WAY AS A QUICK OUTLIER WHILE THE 00Z CMC/UKMET LAG OFF TO THE WEST. IN THE CENTER OF THE SPREAD ARE THE 12Z GFS/00Z ECMWF SO WILL FOLLOW THEIR MIDDLE GROUND SOLUTION. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... RUBIN-OSTER