Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 246 PM EDT Sat May 26 2018 Valid May 26/1200 UTC thru May 30/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z model evaluation including final preferences and confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ***Subtropical Storm Alberto*** ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: See NHC Forecast Closest Guidance: 00z ECMWF/CMC blend The majority of the guidance has come into better agreement on the track and intensity of Alberto, which is currently near western Cuba early Saturday afternoon. The past few runs of the UKMET, including today's 12Z run, are east of the model consensus and not supported by the ensemble mean guidance. The 12Z ECMWF has trended to the east of the 00Z run through early Monday. By Monday evening, the NAM and GFS are quickest with a landfall over the Alabama coast, with the CMC and ECMWF closer to the slower ensemble means. The official NHC track and forecast has additional information pertaining to this storm. ***Disturbances crossing the Great Lakes and Northeast U.S.*** ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 18Z Monday, then non-NAM consensus Confidence: Above average The model guidance is in decent overall agreement regarding a series of shortwave perturbations in the northern stream flow across the Great Lakes and the Northeast U.S. through early Tuesday. The NAM begins to differ some by midday Monday with a stronger ridge over the Midwest and a more amplified and faster trough approaching northern New England Monday night. ***Western U.S. closed low and surface cold front*** ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average A large and slow moving upper low is expected over much of the Intermountain West through the holiday weekend before evolving into an open wave by early Tuesday. The models continue to be in good agreement with the evolution of the closed low over the Great Basin Sunday into Monday. Only modest differences become apparent by Tuesday, with the GFS slightly more amplified and CMC slightly more progressive, but they don't deviate enough to discount from the preferences. A general model blend should suffice with above average confidence on the synoptic scale. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Hamrick