Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 245 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/Quebec. 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 00Z UKMET/ECMWF and 12Z ECENS 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 UT/CO. 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 60 hour time frame as it insists on a more progressive solution compared to the 00Z NAM and 00Z non-NCEP suite of guidance. 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 60 and 84 hours (Thursday to 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. The GFS because of its depth eventually slows down relative to the remaining guidance and ends up actually being the slowest solution relative to its impacts on the Great Lakes and Northeast. During this time, the CMC still appears to be a tad too progressive and weak, but it did trend at least a little stronger with the 00Z cycle. The UKMET for its part trended stronger and faster and actually is rather close to the ECMWF for most of the short-range period. Based on better run to run continuity, the preference will include a blend of the 00Z ECMWF and 12Z ECENS mean, but will also incorporate the 00Z UKMET given its trend toward the ECMWF camp. The 00Z GEFS mean for its part supports the timing of this camp, but is just not as deep. ...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