Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 238 PM EDT Sun Jun 10 2018 Valid Jun 10/1200 UTC thru Jun 14/0000 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 through Monday... Preference: General model blend Confidence: Above average The models are in good agreement with the details of the synoptic scale trough crossing the Northeast through Monday. Will prefer a general model blend. ...Upper trough clipping northern New England Tuesday... Preference: Non-UKMET blend Confidence: Above average The models bring another rather sharp shortwave trough and a compact closed low southeast across Quebec on Tuesday which will get near northern New England. The 12Z UKMET is still keeping its energy a little north of the other well clustered models which includes the details of the surface low and associated front. Will prefer a non-UKMET blend at this time. ...MCVs over the Midwest/OH Valley... ...Frontal zone from the Midwest to the Mid-Atlantic... Preference: General model blend Confidence: Average The non-NCEP guidance in particular has trended rather strongly and favorably toward the 12Z NAM and 12Z GFS solutions the details of the MCVs traversing the Midwest and OH Valley over the next couple of days, and also with the corresponding wave activity along the frontal zone draped from the Midwest to the Mid-Atlantic. Based on the degree of clustering seen in the vort fields and with the surface mass fields, a general model blend will be preferred. However, confidence will be only average as there may continue to be additional small scale MCV development over the next couple of days that the guidance is not currently depicting and will subsequently have difficulty resolving. ...Upper trough crossing the Northwest U.S. and Southwest Canada through Monday... ...Secondary shortwave energy crossing the Northern U.S through Tuesday and Wednesday... ...Cold front sweeping out across the Plains/Midwest with low pressure waves along it... Preference: General model blend Confidence: Above average An anomalously strong upper trough continues to advance inland across the Northwest U.S. and is expected to lift northeast across southwest Canada going through Monday. A rather strong closed low will amplify across Alberta and Saskatchewan by late Monday. This energy is then expected to become effectively blocked by a strong upper level high/ridge axis that is downstream stretching from near and to the north of Hudson Bay. This will allow the bulk of the original energy over the Northwest U.S. to remain consolidated and even retrograde from southwest to west-central Canada. Meanwhile, the models agree in allow a secondary surge of shortwave energy to cross the Northwest U.S. in behind the initial height falls and advance more progressively to the east across the Northern U.S. going through Tuesday and Wednesday as this energy will be south of the blocking pattern up across central Canada. A combination of the initial trough and the secondary energy will allow a cold front to advance gradually out of the West and across the Plains tonight and on Monday, with a well-defined wave of low pressure focusing over the central Plains. This low center will then link up with a quasi-stationary front extending east across the Midwest and OH Valley and advance downstream across these areas Tuesday and Wednesday. The guidance though suggests a strong reconsolidation of low pressure up across southern Ontario/Quebec and then advancing near the Northeast U.S. by the end of the period. The models are in sufficiently good enough agreement that a general model blend can be preferred at this time. ...Upper trough approaching the Pacific Northwest on Tuesday... ...Offshore cold front/surface wave... Preference: General model blend Confidence: Above average The models show great agreement with the idea of another upper trough approaching the Pacific Northwest by Tuesday. A cold front will be offshore the coastal ranges with a surface low west of Vancouver Island. The 12Z NAM, 12Z GFS and 12Z ECMWF are well clustered with timing and depth, and the 12Z UKMET and 12Z CMC have trended a bit more progressive to come into good agreement with these solutions as the energy approaches and then arrives across the Pacific Northwest Tuesday night and Wednesday. Will prefer a general model blend at this time. ...Upper trough over the Gulf of Mexico/Southeast... Preference: General model blend...through 60 hours Non-NAM blend...after 60 hours Confidence: Above average On the larger scale, the persistent upper trough over the Southeast and the Gulf of Mexico is expected to again gradually weaken through about Tuesday. On Wednesday, there is some suggestion of a more defined mid level trough or shear axis returning across the Gulf Coast states. The models are in good agreement through Tuesday, but by Wednesday the 12Z NAM has a strong trough axis extending across the Gulf Coast states than what any of the global models have. Will prefer a general model blend through 60 hours, followed by a non-NAM blend thereafter. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison