Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 233 PM EDT Tue Jul 23 2019 Valid Jul 23/1200 UTC thru Jul 27/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation, Including Preference and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Pacific Northwest/Far Northern Plains/Upper Midwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-UKMET blend Confidence: Slightly above average A closed low will shed shortwave energy onto the Pac NW coast Wednesday morning, before lifting E/NE across southern Canada through day 3 and skirting the northern Plains and upper Midwest. The guidance is generally in very good agreement in both intensity and timing of this feature with the exception of the 12Z UKMET, which is a tad slower than the model consensus after 48 hours. The remaining guidance is well clustered and thus a non-UKMET blend will be preferred. ...Four Corners... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average A strong ridge of high pressure blossoming across the Four Comers will perhaps shift ever so slightly down to the south over the next few days in response to a series of shortwave troughs traversing the northern tier of the nation. This ridge will allow monsoonal moisture to wrap and around the southern and western flanks of the high center through the period. There are some modest difference with the placement and strength of the ridge, but at this point, a general model blend will be preferred to resolve these differences. ...Pacific Northwest on Friday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z GFS/ECMWF Confidence: Slightly above average A shortwave trough is expected to pivot across the Pacific Northwest and adjacent areas of British Columbia on Friday. The 12Z GFS is a tad faster than the model consensus, with the 12Z NAM/CMC solutions the slowest, although there has been some convergence of the guidance with better clustering this cycle. Generally, the best approximation of the model consensus at this point is now the 12Z GFS/ECMWF solutions which are well supported by the latest GEFS mean, and so a GFS/ECMWF blend will be preferred. ...Remainder of the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average A general model blend remains sufficient as the global suite is in very good agreement with the spatial and temporal evolution of a cold front and longwave trough digging across the eastern CONUS. Minor differences exist in where the front and any waves of low pressure may focus along the front, but a general model blend will suffice for now to resolve these differences. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Orrison