Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 243 AM EDT Mon Oct 28 2019 Valid Oct 28/0000 UTC thru Oct 31/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with latest Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Departing mid-level trough/surface low near New England... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The latest model guidance is in very good agreement with the exiting and weakening mid-level trough and associated surface low near New England. A general model blend will be preferred. ...Mid-level trough ejecting into the central Plains on Monday... ...Surface cold front over the lower/mid MS Valley by Tuesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average Although there remain some minor timing differences with a shortwave reaching the central Plains from the Great Basin on Monday, there is enough agreement to support a general model blend. ...Shortwave/clipper low over MT/ND by Monday evening... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average No significant differences exist with this system and run to run continuity has been good so above average confidence exists for a general model blend. ...Powerful closed low over the Intermountain West by Tuesday... ...Energy advancing east across the Plains Wednesday... ...Cold front/surface wave near OH/TN Valleys by Thursday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z ECMWF and 12Z ECENS mean Confidence: Average...becoming below average by midweek A strong deep layer ridge over the Gulf of AK will shift toward northwest Canada on Monday which will allow shortwave energy to dig vigorously southward across southwest Canada and into Intermountain West, leading to the development of a deep longwave trough over the Intermountain West and High Plains by Tuesday. As additional energy digs into the backside of the trough on Wednesday, there should be a strong closed low evolution that settles down toward the Four Corners region. As northern stream shortwave energy begins to break down the large scale ridging over western Canada by the middle of the week, the strong closed low/trough will begin to attain greater progression off to the east with the guidance supporting the closed low advancing east across the central Plains and reaching the middle MS Valley by Thursday. The 00Z NAM is still exhibiting some tendencies to be a tad stronger than all of the global models with the closed low evolution, and by the end of the period, the NAM becomes a slow outlier. The 00Z GFS again is the most progressive of all of the deterministic models, and faster than the 00Z GEFS mean. The 00Z non-NCEP model suite per the UKMET, CMC and ECMWF are all slower than the GFS, but not as slow as the NAM. The 12Z ECENS mean supports the non-NCEP guidance. The preference at this point at the surface with the cold front, surface low development late in the period toward the OH/TN Valley, and the broader upper trough/closed low evolution will be toward a blend of the ECMWF and ECENS mean. Confidence becomes degraded though by the end of the period given the overall deterministic model spread. ...Potential disturbance in the Gulf of Mexico early next week... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average There is currently an area of disturbed weather just east of the Yucatan Peninsula which some of the models track around the western side of the subtropical Atlantic ridge and into the Gulf of Mexico over the next 1 to 2 days. Collectively, the guidance favors little to no development of this system, but the modest energy will gradually become absorbed by the strong cold front reaching the western Gulf Coast region and lower MS Valley by the middle of the week. A general model blend will be preferred. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Orrison