Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 406 AM EDT Sat May 19 2018 Valid May 19/0000 UTC thru May 22/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z model evaluation...with preferences and confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Broad upper trough and embedded MCVs over the Southeast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The models are in good agreement with the larger scale details of this energy as it ejects out of the Southeast and crosses the OH Valley, Mid-Atlantic and southern New England through Saturday. A general model blend will be preferred. ...Upper trough crossing the upper Midwest this weekend... ...Cold front/surface wave crossing the region... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The latest guidance has finally come into rather good agreement with this system, and thus a general model blend will be preferred. ...Upper trough/closed low over the Four Corners... ...Ejecting east across the central Plains this weekend... ...Crossing the Midwest by Monday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z UKMET, 00Z CMC and 00Z ECMWF Confidence: Below average Based on the latest 00Z cycle of guidance, there unfortunately remains a fair degree of uncertainty with the details of the upper trough/closed low energy that will be ejecting out of the Four Corners region. All of the guidance though ultimately takes this energy out across the central Plains through the weekend and then the Midwest going through Monday. The 00Z NAM still looks a little too deep on Saturday as the energy crosses the High Plains. Although it tends to come in closer to the model consensus by late Sunday. The global models are all generally a bit weaker, but after seeing the latest non-NCEP guidance, the 00Z GFS again is seen as becoming the slowest solution at least with the energy aloft as it crosses the Midwest. The 00Z UKMET, 00Z CMC and 00Z ECMWF are all more progressive. Based on the latest trends and model clustering, will downplay the GFS and recommend a non-NCEP consensus. ...Upper trough digging into the West on Sunday... ...Closed low digging into the Southwest Monday and Tuesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The models show good agreement with this system through the period as the height falls arriving across the West ultimately lead to a closed low over the Southwest by Tuesday. Will prefer a general model blend. ...Mid level trough developing over the eastern Gulf of Mexico by Sunday... ...Lifting up across the Southeast on Monday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z NAM and 00Z ECMWF Confidence: Average The models develop a weak mid level trough and possible closed low over the eastern Gulf of Mexico by late Sunday which then lifts up across the Southeast on Monday. The 00Z GFS, 00Z UKMET and to some extent the 00Z CMC all have a more developed/stronger system and support a more defined surface low evolution. Meanwhile, the 00Z NAM and 00Z ECMWF are weaker with basically a surface trough. There is not much support for anything more than a surface trough with this system when looking at the latest ensemble plots, including both GEFS and ECENS suites. So, will lean toward the weaker consensus at this time. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison