Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 245 PM EDT Fri Jun 08 2018 Valid Jun 08/1200 UTC thru Jun 12/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Upper trough crossing the Northeast today... ...Broader trough digging in by Saturday/Sunday... Preference: General model blend Confidence: Above average The models agree in having one shortwave cross the Northeast through today which will be amplifying a bit as it lifts northeast across the Canadian maritimes on Saturday. However, there will be additional shortwave energy dropping southeast from Quebec on Sunday which will sharpen over especially northern New England. The latest models are in good agreement with the evolution of these systems, and thus a general model blend will be preferred. ...Vorts crossing the Northern Plains/Midwest today... ...Crossing the OH Valley and Mid-Atlantic this weekend... ...Frontal zone from the Midwest to the Mid-Atlantic... Preference: Non-NAM blend Confidence: Slightly above average The guidance again takes a series of shortwave impulse across the Northern Plains today and then off to the southeast including the OH Valley and Mid-Atlantic region this weekend with some degree of larger scale trough amplification expected. The 12Z NAM at this point is the most developed with the overall ejection of shortwave energy out of the Midwest and across the OH Valley and Mid-Atlantic region going through the weekend and early next week which corresponds to a bit stronger surface low reflection along a frontal zone draped across the region. The NAM is also farther north with its surface low track, versus all of the global models including the GFS, ECMWF, UKMET and CMC. The UKMET and CMC both clustered/trended in with the GFS/ECMWF camp with this cycle and are well supported by the latest GEFS mean and ECENS mean. Therefore, will suggest a non-NAM blend with the evolution of this energy including the wave activity across the OH Valley and Mid-Atlantic. ...Deep upper trough coming into the Northwest this weekend... ...Cold front sweeping out across the Plains by Monday... Preference: Blend of the 12Z GFS, 12Z UKMET and 12Z ECMWF Confidence: Slightly above average The latest guidance strongly agrees in bringing a rather anomalous trough in across the Northwest U.S. this weekend with pronounced height falls and a strong cold front traversing the Great Basin before then ejecting out across the Plains by Monday. There is 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 also appears perhaps a little slow with its trough evolution by the end of the period. Overall, the best model clustering resides with the 12Z GFS, 12Z UKMET and 12Z ECMWF, and so a blend of these solutions will be preferred. ...Upper low/trough over the Southeast... Preference: General model blend Confidence: Above average The models maintain a large scale weakness over the Southeast through the weekend. Will prefer a general model blend once again. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison