Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1238 AM EDT Sat Apr 11 2020 Valid Apr 11/0000 UTC thru Apr 14/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Closed low exiting the Southwest... ...Energy ejecting toward the lower MS Valley by Sunday... ...Powerful surface low over the Great Lakes by Monday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/12Z UKMET and ECENS/GEFS blend Confidence: Average...through 48 hours Becoming below average...after 48 hours The large, slow-moving cut-off southern stream low over southern California will gradually move toward southern AZ/NM later today and then open up into a progressive shortwave across the southern Plains by early Sunday. By late Sunday, this energy will begin to take on a negative tilt over the lower MS Valley and quickly reach the OH Valley by early Monday. The energy coupled with increasing influence from a strong northern stream trough amplifying over the Upper Midwest Sunday and Monday will lead the way for a powerful surface cyclone to lift over lower MI on Monday. The most recent guidance continues to zero in on a solution for the depth and track of the surface low as it moves from the lower MS Valley to lower Michigan. Ensemble low track spread has lessened in the last 24 hours and now outside of the NAM (too fast) and CMC (too far northwest), the deterministic GFS/UKMET offer fairly reasonable solutions with their mass fields, though the 12Z ECMWF was less preferred for its northwest jump. For now, will side on the further south GFS/UKMET solution and also the ECENS/GEFS. But it's admittedly a lower confidence forecast beyond 48-60 hours and there could be a trend to the northwest like what the 12Z ECMWF suggests. ...Amplifying upper trough over the northern U.S. by Monday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The models bring amplifying shortwave/jet energy southeastward from the southern coast of AK and the adjacent Yukon territory down across southwest Canada and out across the northern Rockies and northern Plains by Sunday. By Monday, this energy will amplify into a deep longwave trough over the northern U.S. that will gradually phase with the aforementioned southern stream energy ejecting across the South and lifting toward the Great Lakes region. The models are in good agreement with the details of the longwave trough evolution. So, a general model blend will be preferred with this. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor