Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1234 AM EDT Tue Oct 29 2019 Valid Oct 29/0000 UTC thru Nov 01/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mid-level trough crossing the Great Lakes on Tuesday... ...Trailing front from the lower MS Valley to the Northeast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average Shortwave energy currently lifting across the Midwest will cross the Great Lakes over the next 24 hours and allow a wave of low pressure to quickly cross the region and lift into Ontario. An attendant cold front meanwhile will cross the OH Valley, lower Great Lakes and move into parts of the Northeast by Tuesday night. The southwestern tail of the front will stall though over the lower MS Valley/western Gulf Coast as the strong upstream height falls over the central Rockies begin to eject east out into the central Plains. There is above average model agreement and continuity such that a general model blend will suffice for this time frame. ...Powerful closed low over the Intermountain West on Tuesday... ...Energy ejecting east across the Plains/Midwest Wednesday... ...Cold front/surface wave near OH/TN Valleys by Thursday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z ECMWF/ECENS mean and 18Z GEFS mean Confidence: Average...becoming below average by Thu/Fri With strong ridging aloft across the eastern Pacific, shortwave energy dropping south into the northern/central Rockies Tuesday will dig vigorously and eventually close off across Colorado. The 00Z FV3-GFS continues to struggle with the timing of its height falls ejecting out across the Plains and Midwest with an emphasis on the 36 to 72 hour time frame as it insists on a more progressive solution compared to the 00Z NAM and 12Z non-NCEP suite of guidance and also the 00Z NAM. The FV3-GFS is also likely much too strong/amplified as the latest GEFS/ECENS means favor a less amplified system and closer to the ECMWF in particular. Between 72 and 84 hours (late Thursday/early Friday), the NAM takes over for being the strongest solution but appears to be too far north overall with the track of its closed low feature. During this time, the CMC becomes a weak/progressive outlier and the UKMET a relatively slow outlier. With the FV3-GFS still appearing too deep through the end of the period, this leaves the ECMWF with support from the GEFS/ECENS means, and thus a blend of these solutions will be preferred. ...Next upper trough/front over the Plains by Friday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The models advertise a new upper trough digging down across the central/northern Plains late Thursday and into Friday along with a new cold front dropping southeast from Canada. Model spread is minimal with this next system, so a general model blend will be preferred for the time being. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Orrison