Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 237 AM EDT Tue Aug 04 2020 Valid Aug 04/0000 UTC thru Aug 07/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Hurricane Isaias... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 03Z NHC advisory package Best model proxy: Multi-model consensus Hurricane Isaias made a landfall at 0310Z near Ocean Isle Beach, NC. The storm is continuing to accelerate off to the north-northeast and will be advancing up across the Mid-Atlantic coastal plain through midday Tuesday, and then crossing New England late Tuesday through Tuesday night. The 00Z model suite, including the NAM/GFS NCEP solutions, and the UKMET/CMC/ECMWF non-NCEP global model solutions are all in very good agreement on the track of Hurricane Isaias over the next 24 hours. The storm will continue to accelerate north-northeast across the coastal plain of the Mid-Atlantic states this morning, and then across the Northeast this afternoon and tonight as it weakens to a tropical storm. The latest global model consensus is a tad faster and a little left of the 03Z NHC forecast track. The 00Z HRRR and 00Z HREF CAM member suite are all a tad left of the NHC track as well. Please consult the latest NHC forecast advisory package for more details. ...Broad trough from the Great Lakes to the Gulf Coast... ...Closed low over Ontario... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average A broad trough extending from the Great Lakes down to the central Gulf Coast will be key in allowing Hurricane Isaias to lift rapidly north-northeast up along the Eastern Seaboard over the next 24 to 36 hours. The models are in good agreement in maintaining the broad trough through the period, but with some stronger northern stream energy over the Great Lakes region favoring a closed low evolution up over Ontario. The models are in good synoptic scale agreement with their mass field evolution, so a general model blend will be preferred. ...Upper trough crossing the Pacific Northwest... ...Energy dropping down over the Northern Plains/Midwest for Tuesday/Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-UKMET blend Confidence: Above average An upper trough will cross far southwest Canada before then dropping southeast and digging across the northern Plains and Midwest Tuesday and Wednesday. The 00Z UKMET gradually becomes a tad weaker with the energy as it digs across the Midwest. The remaining guidance is well clustered through the period as the energy advances into the Great Lakes and reinforces a broad trough over the region. A non-UKMET blend will be preferred at this point. ...Southern stream trough moving into CA by Wednesday... ...Possible closed low over CA by Friday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The models are in very good agreement with the initial trough coming in across CA on Wednesday, and also with reinforcing shortwave energy and possible closed low development over northern CA by Friday. A general model blend will be preferred for the time being. ...Upper trough approaching the Pacific Northwest Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-NAM blend Confidence: Above average A relatively deep trough will be approaching the Pacific Northwest by late Wednesday and the models are overall in very good agreement with their timing and depth. However, the 00Z NAM is a tad on the strong side with its height falls compared to the well-clustered global models. Therefore, a non-NAM blend will be preferred with this next trough. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml This product will terminate August 15, 2020: www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_termination. pdf Orrison