Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1235 AM EDT Tue Mar 24 2020 Valid Mar 24/0000 UTC thru Mar 27/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with Preliminary Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Shortwave tracking from the Central Plains to the East Coast by Wednesday morning ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 18Z GEFS mean/12Z ECMWF/00Z NAM Confidence: Near average The southern stream trough exiting the Rockies and emerging over the Central Plains is forecast to remain intact as it reaches the eastern U.S by Wednesday afternoon. Surface cyclogenesis is in progress across northern Texas and Oklahoma, and this low reaches the central Appalachians and weakens by early Wednesday, with secondary cyclogenesis is likely off the Mid-Atlantic coast by Wednesday afternoon and being a stronger storm. In terms of the models, the 00Z GFS becomes more progressive with the low that redevelops by 18Z Wednesday, and continues through the rest of the forecast period, and also ahead of the 18Z GEFS mean. The 12Z ECMWF and some of the EC ensemble members become slightly more amplified with the storm as it exits the coast, and the UKMET is slightly slower. Longwave trough over the western U.S. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-UKMET blend after 12Z Thursday Confidence: Average The amplified pattern over the eastern Pacific will end up producing a positively tilted longwave trough axis which will slowly progress down the West Coast and eventually move inland across the Desert Southwest by Friday morning. This will eventually support surface cyclogenesis by the end of the week across the central Plains. There is good synoptic scale agreement through Thursday morning, and then the 12Z UKMET becomes more amplified with the trough axis across the Southwest. The 12Z ECMWF is slightly stronger with the surface low that develops over eastern Colorado by Friday morning, but is in decent agreement elsewhere. Storm system crossing northern tier of the U.S. midweek ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-NAM consensus Confidence: Average A shortwave breaks eastward away from the parent western trough and crosses the southern tier of Canada, along with a well-defined surface low and cold front near the Canadian border. Similar to yesterday, the NAM is considerably stronger with the northern shortwave, and becomes slower with the cold front by 00Z Thursday. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Hamrick