Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 315 AM EDT Fri Aug 23 2019 Valid Aug 23/0000 UTC thru Aug 26/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Exceptions: 12z ECMWF/UKMET blend FL to off Carolinas Days 2/3 Confidence: Above average 07z update: The two northern stream systems continue to be in remarkably strong agreement through 12z Monday with little change in thinking/preference but increase confidence to above average, this includes the interaction with the North-central Gulf wave phasing with the digging northern stream trof Sunday into Monday. As for the FL/Gulf Stream surface wave, the ECMWF shifted a tad SE, but the UKMET trended nearly identical in placement/depth with the ECMWF to boost confidence in the initial thinking. The CMC, while still well weaker than the ECMWF/UKMET, did shift the energy northeastward in step. A such will increased confidence in a 00z ECMWF/UKMET blend to slightly above average. ---Prior Discussion--- Deterministic guidance continues to have very strong model agreement with the synoptic flow across the CONUS through early Monday, with the Northern Rockies trof beginning to expand across the Northern Plains with some energy leaking southeast into the MS Valley potentially enhancing a weak surface wave/trof in the Western Gulf by 12z Monday. The only minor difference in the mass field, is seen in the 00z NAM where, the upper tor across S Canada is much broader and therefore a bit deeper than the other guidance. Across the Northeast, the positive tilt trof begins to exit, but with enhancing ridging to the south, the trailing portion of the trof breaks into a weak closed low in the Northeast by 12z Monday, with the 00z GFS a bit east of the remaining guidance, with little effect in the lower troposphere. This leads to a general model blend working for much of CONUS, with perhaps that lower weighting of the NAM at the day 3 period in the Northern Plains. Confidence is slightly above average confidence for this blend. The remaining uncertainty continues with the evolution of the tropical/sub-tropical wave developing in Florida early Sunday and deepening as it intersects with the languishing frontal zone along the Gulf Stream off the east coast into Monday. Here, the 00z NAM has trended toward the earlier preference of the 12z ECMWF/UKMET depicting a stronger wave, yet the NAM is slower to lift out and up the coast, so the NAM adds confidence to the solution but will still prefer the ECMWF/UKMET blend here. The 00z GFS had not budged, suggesting maybe a weak closed low at the apex of the tropical wave, but continues to press it west into the Gulf, like the 00z CMC. Confidence is average in this area of the CONUS. As for TS Ivo in the EPAC, the 00z GFS continues to track closest to the 03z NHC forecast track though closer to the 00z NAM and 12z ECMWF, so a blend of the 3 may be best to approximate the official NHC track for Ivo and the moisture it pumps north into NW Mexico and the Southwest. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Gallina