Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1235 AM EDT Sat Jul 25 2020 Valid Jul 25/0000 UTC thru Jul 28/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mid-upper level troughing tracking from the Northwest into the north-central U.S. through the weekend... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average Shortwave energy will skirt southwestern to southern Canada over the next 36 hours before closing off and settling west of the Hudson Bay toward the end of the forecast period. The retrograding upper ridge over the southern US toward the southwest US and some phasing with energy coming out of the Front Range will allow the trough to encompass more of the Great Lakes region by Tuesday/Wednesday. The latest deterministic guidance shows this idea and evolution fairly well and agrees on the synoptic pattern such that for mass field purposes a general model blend is preferred. ...Tropical Storm Hanna... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Official NHC track Best Model Proxy: 00Z GFS, 12Z UKMET/ECMWF blend Confidence: See latest NHC products T.S. Hanna will make landfall along the South Texas coast on Saturday and outside of the CMC, the rest of the model guidance has clustered very tightly on a track with respect to location and speed. The 12Z CMC is a bit north and too fast comapred to the official track while the NAM is off to the south a touch. The best model proxy is the 00Z GFS, 12Z UKMET/ECMWF. Strengthening of the mid-level subtropical ridge north of Hanna should steer the system more westward during the day Saturday and then west-southwestward Saturday night as the system crosses through the lower Rio Grande Valley. On Sunday, Hanna should be weakening over northeast Mexico. For the latest information on Hanna, see the most recent advisory statement from the National Hurricane Center. ...Upper low/trough over California... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average A broad upper trough and embedded closed low over CA will generally remain in place through early next week, with some tendency for the energy to begin lifting north by the end of the period. Overall, the models are in good agreement through the period with the handling of this energy, so a general model blend will be preferred. 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 Taylor