MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1259 AM EDT THU AUG 11 2016 VALID AUG 11/0000 UTC THRU AUG 14/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 00Z NAM/GFS ALONG WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... ...WESTWARD DRIFTING TUTT CELL AFFECTING THE WESTERN/CENTRAL GULF COASTS... PRELIMINARY PREFERENCE: BLEND OF THE 00Z NAM/12Z UKMET FORECAST CONFIDENCE: BELOW AVERAGE A BROAD CYCLONIC CIRCULATION WHICH HAS BEEN AFFECTING THE NORTHEASTERN GULF OF MX FOR DAYS NOW HAS FINALLY DRIFTED WESTWARD. RECENT WATER VAPOR IMAGERY SHOWED THIS UPPER LOW SPINNING SOUTH OF SOUTHERN MS/AL WITH MUCH OF THE COLDEST CLOUD TOPS ALONG THE NORTHWESTERN FLANK OF THIS SYSTEM. HOWEVER...IT HAS WEAKENED IN THE PAST FEW HOURS WITH THE LOSS OF SURFACE HEATING. BY 13/1200Z...MODELS HAVE THIS TUTT CELL SOMEWHERE BETWEEN LA/MS DEPENDING ON THE PIECE OF GUIDANCE. ON THE FAR WESTERN END ARE THE RECENT GFS/ECMWF SUITES WHILE THE 00Z CMC DOES NOT MOVE THE CIRCULATION APPRECIABLY DURING THE FIRST COUPLE OF DAYS. GIVEN THIS SYSTEM HAS NOT MOVED A SIGNIFICANT DISTANCE THE PAST SEVERAL DAYS...DO NOT WANT TO MOVE THIS CIRCULATION TOO MUCH THE NEXT FEW DAYS. WILL PLAY THE MIDDLE OF THE SPREAD WITH THE 00Z NAM/12Z UKMET REASONABLY IN THE CENTER. CONFIDENCE IS LOW GIVEN RECENT SOLUTIONS HAVE BEEN TOO AGGRESSIVE IN ATTEMPTING TO USHER THIS CIRCULATION OUT OF THE NORTHERN GULF OF MX. ...LEAD CLOSED LOW CROSSING SOUTHERN SASKATCHEWAN EARLY IN THE PERIOD... ...ATTENDANT MEAN UPPER TROUGH GRADUALLY REACHING THE UPPER GREAT LAKES BY 14/1200Z... ...ASSOCIATED SURFACE LOWS/FRONTAL BOUNDARIES... PRELIMINARY PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF FORECAST CONFIDENCE: AVERAGE A STRONG UPPER LOW CURRENTLY LIFTING TOWARD SOUTHERN SASKATCHEWAN HAS HELPED DRIVE AN ACTIVE NIGHT OF CONVECTION ACROSS THE NORTHERN PLAINS INTO THE UPPER MIDWEST. THE CORE OF LOWER MID-LEVEL HEIGHTS SHOULD GENERALLY REMAIN NORTH OF THE INTERNATIONAL BORDER WHILE RESIDUAL LONGWAVE TROUGHING PROPAGATES SLOWLY TOWARD THE EAST THIS WEEK. MULTIPLE PERTURBATIONS WITHIN THE SOUTHWESTERLY FLOW ALOFT WILL TRACK ALONG THE SLOW-MOVING FRONTAL ZONE SETTING THE STAGE FOR AN ACTIVE PERIOD OF PRECIPITATION. WHILE DIFFERENCES ALOFT ARE NOT LARGE...THERE IS SOME SPREAD WITH THE TIMING OF THE FRONT AS WELL AS THE SURFACE WAVE MOVING THROUGH THE GREAT LAKES. ENSEMBLE LOW PLOTS SHOW THIS ALTHOUGH THEY DO APPEAR TO BE FAVORING MORE THAN ONE WAVE ON THE BOUNDARY. AT THIS TIME...WILL SPLIT THE DIFFERENCE BETWEEN THE 00Z GFS/12Z ECMWF UNTIL FURTHER GUIDANCE ARRIVES. ...PACIFIC SHORTWAVE NEAR THE WEST COAST BY LATE IN THE WEEKEND... PRELIMINARY PREFERENCE: A NON-12Z CMC MODEL COMPROMISE FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE TOWARD THE END OF THE PERIOD...A MODEST SHORTWAVE BEGINS TO APPROACH THE WEST COAST. THE 12Z CMC IS SIGNIFICANTLY SLOWER THAN ANY OTHER MODEL...PARTICULARLY INTO THE WEEKEND. OTHER MODELS ARE CLOSE ENOUGH TO ONE ANOTHER TO SUPPORT A NON-12Z CMC MODEL COMPROMISE HERE. ...MID-LEVEL FEATURE APPROACHING THE UPPER RIO GRANDE RIVER VALLEY... PRELIMINARY PREFERENCE: A NON-00Z NAM/21Z SREF MEAN MODEL BLEND FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE A RATHER PRONOUNCED MID-LEVEL LOW CENTER APPEARS OVER NORTH-CENTRAL MX...POSSIBLY CROSSING THE UPPER RIO GRANDE RIVER. THIS BROAD CIRCULATION WILL ALSO BE A FOCI FOR HEAVY RAINFALL OVER WEST TX WITH OVERALL PLACEMENT OF THIS SYSTEM UNCERTAIN. THE 00Z NAM/21Z SREF MEAN SEEM TO BE ON OPPOSITE ENDS OF THE SPECTRUM BEING THE FURTHEST AWAY FROM THE CONSENSUS. WILL STAY AWAY FROM THESE SOLUTIONS FAVORING A COMPROMISE OF OTHER MODELS. KEPT CONFIDENCE SLIGHTLY BELOW AVERAGE GIVEN UNCERTAINTY IN THE TRACK AND INTENSITY. RUBIN-OSTER www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...