Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 303 PM EDT Tue Jul 09 2019 Valid Jul 09/1200 UTC thru Jul 13/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation Including Preference and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend (Northern Plains to Northeast) Blend of the 12Z GFS/CMC/ECMWF (Gulf Coast States) Blend of the 12Z GFS/ECMWF (Pacific Northwest) Confidence: Slightly above average For the majority of the CONUS, there continues to be reasonably good agreement on the details of the synoptic pattern which will include a robust upper trough/closed low feature over the northern Plains advancing east-southeast through the Great Lakes and Northeast through the end of the week. Also, there will be a modestly negative height anomaly brushing the Pacific Northwest and then reloading offshore the Northwest by the end of the period. Meanwhile, a strong deep layer ridge builds across the central U.S. which will advance west well across the Four Corners region and stretch as far east as the middle MS Valley. The strength and position of this ridge will be important in dictating the ultimate track of any tropical cyclone development across the northern Gulf of Mexico over the next several days. Regarding the initial northern stream trough/closed low over the northern Plains, the 12Z NAM is now overall the slowest solution, with the 12Z GFS the most progressive. The 12Z CMC/UKMET/ECMWF solutions are clustered generally in between. Overall, the model spread is rather modest at this point, and there has been some convergence of solutions on the evolution of this system. Thus, a general model blend will be preferred. The other region of focus will certainly be the northern Gulf Coast region as the models have all come into very good agreement on taking a broad area of low pressure over the FL Panhandle down to the west-southwest over the northern Gulf of Mexico where tropical cyclone development is likely to occur. The 12Z NAM is the most progressive and weakest solution and supports a direct impact along the middle southeast TX coast by early Friday. Meanwhile, the global models are all slower and deeper, with the 12Z ECMWF now the slowest solution after having trended slower from its 00Z run. The 12Z CMC/ECMWF solutions are much more emphatic on stronger impacts over southern LA by Friday, with the CMC a bit faster by comparison. Meanwhile, the 12Z UKMET and 12Z GFS take the cyclone farther west, with the UKMET the strongest overall solution, and a bit faster than the GFS. The GFS and UKMET would focus impacts across portions of southern LA, but also toward southwest LA and the upper TX coast Friday and Friday night. The 12Z GEFS mean and 00Z ECENS mean favor a solution away from the NAM for sure, and support a slower evolution relative to the UKMET. Generally, a blend of the CMC/GFS and ECMWF would be best supported by the broader ensemble suite at this time. Otherwise, the guidance does support a reloading upper trough offshore the Pacific Northwest by the end of the period. The 12Z NAM is the slowest and deepest with this solution, with the 12Z UKMET the fastest. Overall, the 12Z CMC is now the weakest solution, but is not as fast as the UKMET. The 12Z GFS and 12Z ECMWF are now the best clustered in between slower and faster camps, and with a reasonable depth that is supported by the 12Z GEFS mean and 00Z ECENS mean. Based on this, a blend of the GFS and ECMWF will be preferred for the energy offshore the Pacific Northwest toward the end of the period. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Orrison