Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1243 AM EDT Thu May 10 2018 Valid May 10/0000 UTC thru May 13/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z NAM/GFS Evaluation with preliminary model preferences ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS initialization errors do not seem to degrade their short range forecasts. Mid- to upper-level low sagging into the Great Basin ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The guidance is quite similar to this system's behavior over the next few days. A compromise of the 00z GFS, 00z NAM, 12z UKMET, 12z Canadian, and 12z ECMWF is preferred with above average confidence. Base of the broad eastern Canadian trough across Midwest/Mid-Atlantic ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~ Preference: Non-Canadian blend; confidence slightly above ave Shortwaves of minimal amplitude are expected to track across the Great Lakes and Northeast from Friday into Sunday. Surface high pressure of above 1020 hPa parked over the Great Lakes with possible convection near the frontal zone to its south should lead to a more southern solution to the boundary and any waves from the Midwest through the Mid-Atlantic states, somewhat undercutting the weak ridge between the upper low in the Gulf and the other troughs across the Great Basin and eastern Canada. The above favors a compromise of the 12z UKMET, 12z ECMWF, 00z NAM, and 00z GFS with slightly above average confidence. Upper trough/low moving east through the Gulf of Mexico ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: GFS/ECMWF blend; confidence average The guidance shows the idea of a broad upper trough progressing through the Gulf towards FL with time. The UKMET is generally north of the other guidance and brings the heavy rain footprint more northerly along the FL coast. The 12z Canadian/00z NAM were the slowest, which led to the lightest amounts. The synoptic pattern of fresh trade winds with an approaching upper trough can be a highly localized wet pattern for areas downwind of the Bahamas across the southern peninsula. Believe a compromise of the 00z GFS/12z ECMWF is best overall with this system with average confidence. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Roth