Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1255 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 00Z UKMET is a little slower with this system compared to the other models and keeps its energy farther north along with its 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: Blend of the 12Z NAM/12Z GFS...through 24 hours 12Z NAM/12Z GFS/00Z UKMET blend...after 24 hours Confidence: Average The guidance remains in rather poor agreement with the handling of the MCVs traversing the Midwest and OH Valley over the next couple of days. The 00Z CMC and especially the 00Z ECMWF maintain a stronger and farther north track of the MCV that is currently approaching southern Lake Michigan as this energy gradually shifts east across the OH Valley and then the Mid-Atlantic region going through Monday and Tuesday. The CMC and ECMWF also appear to not even have the MCV that is currently over western IA which will also be advancing east over the next couple of days in tandem with the initial energy near Lake Michigan. The 12Z NAM and 12Z GFS show a more reasonable solution with the evolution of this energy and are not as wrapped up like the ECMWF and CMC. Both the NAM and GFS appear to at least be capturing the energy over western IA in their initialization fields this morning. The 00Z UKMET overall leans toward the NAM and GFS camp by later Monday and Tuesday as the energy reaches the OH Valley and Mid-Atlantic, but the UKMET looks a little too intense and too far north for about the first 24 hours of the period going through early Monday. Will prefer a solution toward the NAM and GFS through 24 hours, followed by a blend of the NAM, GFS and ECMWF thereafter. ...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...through 60 hours Non-UKMET consensus...after 60 hours Confidence: Slightly 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 remarkably good agreement with their mass fields through about 60 hours as the initial energy lifts up across Canada and the secondary energy crosses the Northern U.S., but after 60 hours, the UKMET is more out of tolerance with the remaining guidance concerning the details of the upper low over southwest to west-central Canada, and also it is likely too progressive with the shortwave energy farther south. This results in a gradually more progressive surface wave over the OH Valley and near the Northeast later in the period. The remaining guidance is relatively well clustered with their mass fields with only modest spread. Will prefer a general model blend through 60 hours, and a non-UKMET consensus after 60 hours. ...Upper trough approaching the Northwest on Tuesday... ...Offshore cold front/surface wave... Preference: Blend of the 12Z NAM, 12Z GFS and 00Z ECMWF Confidence: Above average The models show great agreement with the idea of another upper trough approaching the Northwest by Tuesday. A cold front should be positioned off the coast with a surface low west of Vancouver Island. The 12Z NAM, 12Z GFS and 00Z ECMWF are well clustered with timing and depth, but the 00Z UKMET and 00Z CMC are a little slower as the energy begins to arrive across the Pacific Northwest Tuesday night and Wednesday. The latest GEFS mean and ECENS mean are much more in favor of the slightly more progressive consensus, and thus a blend of the NAM, GFS and ECMWF will be preferred. ...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