Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1117 AM EST Mon Nov 11 2019 Valid Nov 11/1200 UTC thru Nov 15/0000 UTC ..See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... ...12Z Model Evaluation with Preferences and Confidence... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...CONUS through 84hrs (15.00z)... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 13.12z Non-NAM thereafter Confidence: Slightly above average Large scale pattern appears to be dominated by cold air surges out of the Canadian Arctic into the Plains. Current RADAR and GOES imagery shows a shortwave moving through the Great Lakes with a trailing frontal zone across the Ohio Valley. A very strong high pressure/cold air outbreak will drive the cold front into the Western Gulf while providing frontogenesis and cyclogenesis across the Upper Ohio Valley tonight through New England. Guidance has come into solid agreement with this wave to support a general model blend at above average confidence. Uncertainty increases (though not significantly), with the closed low over Baja California starting to progress east into the Northern Mexico, as well as, a fast moving shortwave emerging out of the Northeast Pacific by early Tuesday that drops into the Central Plains by Wed. Here, the guidance remains fairly well agreed upon with eventual, but typical timing differences with both systems with the GFS/NAM/UKMET faster and the ECMWF/CMC slower. The 12z NAM is particularly out of sync, mostly in retaining shallow cold air along the S TX/Mexico Gulf coast, reducing the northward press of moisture as the close low presses East. The 12z run is better than prior runs but still not serviceable in a preferred blend. The NAM is also quite fast with the northern stream shortwave (likely due to reduced interaction), this negatively affects it across the Ohio Valley into the Mid-Atlantic by the end of the forecast period. The 00z ECMWF with its typical slowness, allows for greater southward amplification of the northern stream shortwave, this allows for greater phasing/northward surge of low level moisture, this is opposed by the faster GFS. However, the evolution/interaction appears meteorologically sound, that a blend of the two in timing will suffice (very close to the ECENS and GEFS solutions). As such, a Non-NAM blend is supported with both of these waves at slightly above average confidence. Please note: The 00z CMC is agreed with the solutions but noted that the cold surge through the Central Rockies and westward press of the frontal zone may be a bit overdone late Mon into Tues. As for the West...with a firm ridge across the western half of the Inter-mountain region/West Coast, is suppressed a bit on Tues with the passing northern stream shortwave, but another shortwave ridge builds in its wake. While it is progressive, it will delay/deflect moisture and next shortwave height-falls further north, with only a weak sub-tropical stream shortwave moving through the area on Thursday with little QPF expected, except the Olympic Range/Western WA. There is some spread with the wave but not too bad, to support a general model blend at slightly above average confidence. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Gallina