Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1235 PM EDT Sat Jul 25 2020 Valid Jul 25/1200 UTC thru Jul 29/0000 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 12Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mid-upper level troughing over the northern CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average A mid to upper-level trough over the Northwest and adjacent areas of southwest Canada will advance east through early next week and gradually amplify over portions of the Midwest and Great Lakes region going through Tuesday. In fact, all of the models show a well-developed upper low just to the north over Ontario by the end of the period. The model guidance is reasonably well clustered with the timing and evolution of this energy along with the attendant cold front crossing portions of the Plains, Midwest and eventually the eastern U.S. So, a general model blend will again be preferred. ...Hurricane Hanna... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Official NHC track Best Model Proxy: 12Z NAM/GFS blend Confidence: See latest NHC products Hurricane Hanna will make landfall along the South Texas coast this afternoon and across Deep South Texas tonight before crossing into northeast Mexico early on Sunday. The 12Z NAM/GFS solutions appear generally to be the closest to the 15Z NHC forecast track. The 00Z UKMET becomes a bit of a faster outlier solution by this evening and overnight and is also a bit south of the NHC track. The 00Z CMC/ECMWF solutions are both just a little faster and a tad north of the NHC track. For the latest information on Hanna, please consult the latest NHC public advisory. ...Upper trough/low over California/Great Basin... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average A broad upper trough and embedded closed low over CA will generally remain in place over the next couple of days, but should then gradually advance northeast and weaken through the Great Basin by Tuesday. Overall, the models are in good agreement through the period with the handling of this energy, so a general model blend will be preferred. ...New upper trough/low approaching California by Tuesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-CMC blend Confidence: Above average A new upper trough and embedded closed low will be approaching CA by late Tuesday. The 00Z CMC is a progressive outlier with this energy. The remaining guidance is slower and agrees in still having the bulk of the energy offshore at least through this period, so a non-CMC 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 Orrison