Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 255 AM EDT Mon Jun 08 2020 Valid Jun 08/0000 UTC thru Jun 11/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Final Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Positively tilted trough over the Intermountain West that spins off a low that crosses the central Rockies Monday night and lifts over the Upper Midwest Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: non-NAM/GFS blend Confidence: Average A reinforcing shortwave moving along the positively tilted trough over the Great Basin spins off as its own trough that crosses the CO/NM border Monday night and develops into a low as it into the south-central Great Plains Tuesday. This low trails the remnants of Cristobal then through midweek as it turns north and crosses the Great Lakes Wednesday night. There is good agreement on this pattern for non-NCEP models. The 00Z NAM develops the low sooner than any other model and is therefore slower with the progression across the Great Plains Tuesday and a slower northward transition on Wednesday. The 00Z GFS is much more progressive than any other guidance and has a greater interaction of the spun off low and the Cristobal remnants making for a much deeper low with a farther west track over the Upper Midwest than the rest. The ECMWF/UKMET/CMC all have a low slower than the GFS crossing the central Rockies allowing Cristobal to get farther ahead. Preference is for the 00Z ECMWF/UKMET/CMC which are in good agreement. ...Cristobal... ~~~~~~~~~~~~~~~~~~ Preference: Non-GFS blend Confidence: Refer to NHC products Non-GFS models are well-clustered through Tuesday night for the Cristobal remnants track up the Mississippi River then to the Upper Midwest. The 03Z NHC advisory remains on the faster side of the consensus solution of 00Z guidance through Tuesday night. Any interaction with the low approaching from the central Plains on Tuesday will need to be monitored, but confidence is growing that the GFS is too aggressive with this interaction. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml ...Southern Gulf of Alaska Low Stalling off the BC Coast Tuesday night through Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Model Blend Confidence: Average There is decent agreement on position and intensity of the low stalling off the BC Coast (near the border with AK) through Day 2 which is when moist onshore flow provides precip to the Pac NW. Guidance diverges in placement of the low (that remains offshore) Wednesday night, but little if any QPF is expected over the Northwest CONUS on Day 3, so for practical purposes a general model blend works for this feature which has the most impact through Day 2. Jackson