Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1242 PM EDT Sat Jun 09 2018 Valid Jun 09/1200 UTC thru Jun 13/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Broad trough over the Northeast through Sunday... Preference: General model blend Confidence: Above average The models agree in having additional shortwave energy dropping southeast from Quebec and in across the Northeast through Sunday which will reinforce and actually sharpen the trough over the Northeast through Monday before it then begins to lift out. The latest models are in good agreement and so a general model blend will be preferred. ...Strong vorts over the Upper Midwest today... ...Crossing the OH Valley and Mid-Atlantic this weekend... ...Frontal zone from the Midwest to the Mid-Atlantic... Preference: 12Z NAM/12Z GFS blend...through 36 hours 12Z GFS/00Z ECMWF blend...after 36 hours Confidence: Average The guidance agrees in taking a couple of well-defined vort centers this morning (one over southwest MN, and one over northern IL) off to the east and southeast through the weekend which will bring collectively a mid level trough down across portions of the OH Valley and Mid-Atlantic region through Sunday and Monday. The 00Z ECMWF and 00Z CMC both appear too weak with their respective vorts over the Midwest this morning, as the 12Z NAM, 12Z GFS and 00Z UKMET all are much more aligned with the morning satellite/radar trends. The NAM, GFS and UKMET all have better clustering with respect to these vorts through Sunday as the energy drops southeast toward the OH Valley. However, one concern with the UKMET is that it remains much too strong in time with the vort that is currently over southwest MN. As this stronger energy approaches the OH Valley, the UKMET ends up with a much stronger surface low riding along the frontal zone that will be draped from the Midwest to the Mid-Atlantic region. The models otherwise agree on more modest wave activity developing and moving east along this front through Monday, although the CMC looks too weak with this. By Monday, the GFS and ECMWF tend to come back into decent agreement with the troughing over the Mid-Atlantic as by then the CMC and UKMET are likely too progressive. Based on the latest trends and clustering, will prefer a blend of the NAM and GFS through 36 hours, followed by a blend of the GFS and ECMWF thereafter. ...Deep upper trough coming into the Northwest this weekend... ...Cold front sweeping out across the Plains by Monday... Preference: Blend of the 12Z GFS and 12Z ECMWF Confidence: Above average An anomalously strong upper trough is currently coming into the Pacific Northwest and will be bringing pronounced height falls and a strong cold front in across the Great Basin before then ejecting out across the Plains by Monday. There energy will then be crossing the upper Midwest by Tuesday. The models are in rather good agreement with the details of the height falls and timing features involving the front as well, but the 12Z NAM does appear a little too strong with its height falls across the northern Rockies and adjacent areas of southwest Canada. The 12Z CMC again also appears perhaps a little slow with its trough evolution as the energy arrives across the High Plains on Monday. Overall, the best model clustering resides with the 12Z GFS and 12Z ECMWF, and so a blend of these solutions will be preferred. ...Weak surface low along the SC coast... ...Upper trough over the Gulf of Mexico/Southeast... Preference: General model blend Confidence: Above average The agrees in taking the weak surface low near the SC coast this morning gradually off to the northeast near the eastern NC coastal plain through Sunday before then dissipating it. On the larger scale, the persistent upper trough over the Southeast and the Gulf of Mexico is expected to gradually weaken through the period, with just a modest weakness left over the Southeast by Tuesday. A general model blend will be preferred with these features. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison