Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1207 AM EDT Sun Jun 14 2020 Valid Jun 14/0000 UTC thru Jun 17/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Closed low developing in Southern Appalachians Mon/Tues... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average GOES-E WV depicts the a small compact shortwave over lower Lake Michigan and this is the feature that will descend through the Ohio Valley slowly and expand into the fairly static closed low across the Southeast through the early portion of next week. Overall, differences appear to be getting smaller, though the ECMWF/CMC are both a bit south and east of the NAM/GFS with the UKMET split between. Overall, the differences will be driven by mesoscale and convective processes that can be handled within a general model blend. Confidence is above average ...Interaction of shortwave lifting through SW Canada with a closed low advecting onshore Washington Sunday... ...Secondary closed low moving into the Northwest Tuesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 16.00z 00z ECMWF/CMC thereafter Confidence: Above average transitioning to average after 48hrs Three main shortwave features will help define a larger scale gyre set-up that develops across SW Canada into the Pacific Northwest and Northern US Rockies across the next few days. The initial shortwave that emerged from CA is advancing through the Great Basin and elongating the closed low along WA coast/Vancouver Island at this time. The binary interaction has started to become much more focused and agreed upon though there remains some minor model spread as the lead shortwave amplifies across SW Canada and presses the frontal zone out of the High Plains into the Northern Plains through Monday. The 00z GFS is still a tad faster, and therefore tighter/west with the amplifying shortwave but overall the placement/timing of the synoptic features have resolved to support a general model blend through 48hrs, including the acceleration of the older closed low moving through the NW into the High Plains Monday. Thereafter, the model spread begins to increase with the approach of the next shortwave out of the North Pacific. This is a compact shortwave/closed low, that is actually quite progressive through the Gulf of AK. A small timing wobble within the broader cyclonic flow on Monday, will help to kick the nose of the jet through the Pacific NW and help to expand the larger gyre/interaction with the SW Canada systems' energy. This will also support a strong surface wave response Tuesday across WY into the Northern Plains, with the bulk/core of the close low still remaining upstream maintaining/digging the Western Trof by 00z Wed. The 00z GFS shows some bias of pressing the initial height-falls out fast, leading to a eastward shift of the frontal zone across the Plains as well as an acceleration of the surface wave north into Canada later in the day. This seems too aggressive and in line with typical negative bias. The 00z NAM and 12z UKMET are a bit slower but also much more amplified digging the trof through the Snake River Plains into the Northern Rockies at the same time, while the ECMWF/CMC are more middle ground within the ensemble suite and more in-line with the flow pattern/timing in interaction with the precursory wave. As such will favor the 00z ECMWF/CMC over the GFS/NAM/UKMET after 16.00z (48hrs). Confidence is above average prior to 16.00z but becoming average thereafter given uncertainty in magnitude of shortwave interaction placement through complex terrain in a very progressive flow regime. Gallina Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml