Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 138 AM EST Fri Nov 08 2019 Valid Nov 08/0000 UTC thru Nov 11/1200 UTC ..See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... ...00Z NAM/GFS Evaluation with Preliminary Preferences and Confidence... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Shortwaves cutting into the Pacific Northwest Ridge... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z NAM, 00Z GFS, 00Z ECMWF blend with increasing weight on ECMWF through 12Z/11 Confidence: Slightly Below Average ...07Z update... Subtle changes were made by the 00Z ECMWF/UKMET/CMC toward the previous preference regarding the troughing downstream into the north-central U.S., but the changes were not large enough to include the UKMET or CMC in the preference. ...previous discussion follows... The latest guidance continues to show differences on the temporary breakdown of an anomalous eastern Pacific ridge late today into Saturday. Trends show convergence in solutions compared to yesterday with differences with shortwave intensity through Saturday morning off of the Northwest coastline. The 12Z UKMET looks to be the most aggressive with a favored model blend represented by a 12Z ECMWF/00Z NAM/00Z GFS blend. Attention then turns downstream across the north-central CONUS as troughing advancing south from central Canada reaches the Northern Tier on Sunday. The 00Z GFS has trended toward the remaining model consensus compared to yesterday but continues to lie on the southern edge of the ensemble spread regarding 500 mb height amplification into the north-central CONUS on Sunday into Monday. Timing differences with a related cold front through the Great Plains show the 00Z GFS as the fastest while the 12Z UKMET makes up the other end of the spectrum with a slower progression. A combination of the 12Z ECMWF/00Z NAM appears to be a favorable blend early on but the 00Z NAM begins to lag in timing with elements of the GFS looking more reasonable when compared to the NAM. The 12Z ECMWF is a preferred middle ground by Monday morning (12Z/11) but pieces of the 00Z NAM and 00Z GFS are usable elsewhere across the Plains and Midwest on Sunday. ...Remainder of overall pattern across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average ...07Z update... No significant changes were noted with the 00Z ECMWF/UKMET/CMC across the remainder of the U.S. compared to their previous 12Z cycles, therefore a general model blend remains as the preference. ...previous discussion follows... A ridge-trough pattern from west to east starts off the short range period. There is flattening of the flow into Saturday evening with a fast upper level flow setting up from the Pacific Northwest into the Mid-Atlantic region. Amplification reappears by Monday morning with strong ridging along the West Coast and downstream troughing into the north-central CONUS. A closed low west of southern California is forecast to near the Baja Peninsula through Monday morning. Regarding the closed low off of the Baja Peninsula and an exiting cold front from the East later today, the models are in fair agreement with a general model blend recommended. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Otto