Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1232 AM EDT Wed Sep 12 2018 Valid Sep 12/0000 UTC thru Sep 15/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Pacific Northwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/12z ECMWF Confidence: Average Persistent trough across the northwest will be reinforced by shortwaves rotating into the base of the upper trough. The first wave moves onshore today and ejects northeast into the northern Rockies and shears out. This is followed by second wave on Thu that also deamplifies as it drifts inland. Finally a third wave amplifies off the coast on Friday and Fri night, creating higher heights inland over the northern Rockies. The 00z GFS/18z GEFS Mean/12z ECMWF/12 ECMWF Ensemble mean/00z NAM cluster well well 700-500 mb so a blend of these solutions will work well. The 12z UKMET was out of phase with the dominant cluster and thus is considered to be a low probability solution. ...Troughs over southern and eastern Texas... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS, 12Z ECWMF blend Confidence: Average There are 2 trough forecast to impact southern and eastern Texas through day 3. The initial trough in place gradually deamplifies and drifts inland as a second trough develops over the Gulf of Mexico and moves west towards Texas, arriving by Friday. There are timing differences, with the 21z SREF and 12z UKMET ahead of the low track of the ECMWF/GEFS/00z GFS on Friday. The NAM develops a closed low a bit north of those solutions, so will be weighted less in the forecast. See the NHC tropical weather outlook for development potential. ...Hurricane Florence... ~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: See NHC forecast discussion Confidence: See NHC forecast discussion The models are gradually converging with the 00z GFS showing good run to run continuity and not far from the NHC forecast for the first few days. The 00z GFS and 12z ECMWF and 12z ECMWF Ensemble Mean are closer to the official track than the 12z UKMET/12z Canadian global/00z NAM. Please refer to the latest NHC discussions and products for more detailed information. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Petersen