Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 235 PM EDT Mon Oct 29 2018 Valid Oct 29/1200 UTC thru Nov 02/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12z GFS/NAM/UKMET Confidence: Average The 12z ECMWF followed its 00z run with the stronger, more southerly solution with the vorticity maximum pushing through Texas. This leads to a slower progression of the QPF axis through the mid-MS and lower OH Valleys. Overall, this is in contrast to most of the other global deterministic models. The 12z UKMET is in good agreement with the GFS/NAM through 84 hours. As a result, will lean on a blend of the GFS/NAM/UKMET for this cycle. ---previous discussion--- A couple of shortwaves moving across the western US will eventually carve out a longwave trough over the central US and spawning several low pressures through the southern Plains into the Ohio Valley and Great Lakes. An active storm pattern will evolve this week with several episodes of precipitation. The biggest differences among the deterministic models remain on the southern vort max kicking out across Texas before lifting into the lower/mid-MS Valley. The 12z GFS/NAM plus the 00z UKMET are in rather good agreement with this vort max across Texas through 01.00z. The 12z GFS did trend a bit slower compared to the 06z run and is inching toward the slower 00z ECMWF (that was not considered for QPF) but the placement and magnitude is more reasonable and within the ensemble spread. The 00z ECMWF and CMC is too far south compared to the other deterministic models and ensemble spread. The GFS/NAM, along with the UKMET, show good consistency through the end of the forecast period. This slightly slower progression with the mid-level wave suggests potential for higher QPF for the lower Ohio Valley. Overall, a blend of the 12z GFS/NAM, with the 00z UKMET seems to be a good approach at this time. Across the Pacific Northwest, the model agreement across the board is better with respect to the mass fields and QPF. Earlier cycles showed some timing and placement issues, but these seem to be resolved better such that a general model blend (12z GFS/NAM, 00z ECMWF/UKMET/CMC) can be used. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor