Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1118 AM EST Fri Feb 14 2020 Valid Feb 14/1200 UTC thru Feb 18/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model evaluation with preferences & confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Midwest/Mississippi Valley and East... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Exception: GFS/ECMWF blend for QPF along Gulf/Southeast Confidence: Above Average Large scale trof is finally exiting the east coast today with only the lingering showers along the front across Florida, followed by the cold Arctic airmass/high pressure which evolve very similarly within the guidance suite. This high will be shunted along due to the approach of a stronger shortwave moving through Central Canada that clips the Great Lakes late Saturday into Sunday. Across this region, general model blend remains solid preference with high confidence; however, the very distant influences of weak return Western Gulf moisture supports thunderstorm activity along the Central Gulf Coast on Sunday that slide into the southeast. Given the weakness of the flow from a synoptic standpoint there is modest model uncertainty in the QPF placement; but a GFS/ECWMF blend seems to be best combination for some increased confidence. ...Pacific NW system Sat/Sun,reaching Northern/Central Plains Monday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 12z GFS/06z GEFS and 00z ECMWF/CMC/ECENS blend after 17.00z Confidence: Slightly above to above average It is the next Pacific Northwest system coming in late Saturday to Sunday that had shown the greatest uncertainty yesterday. The ECMWF trended slower, yesterday along with the CMC and it appears the GFS/GEFS/NAM has shifted eastward as an overall better compromise of timing. This brings much stronger agreement/confidence especially in timing through Sunday. There remains some timing/amplitude differences by day 3 as the system spills in the Northern and Central Plains. The 12z NAM and 00z UKMET are a bit more aggressive with greater sharpening of the trof over the Great Basin/Utah by the very end of the period which will lead to an elongation/lagging relative to the more progressive ECMWF/CMC solutions with the GFS more in the middle, yet favoring the ECMWF/CMC slightly more. However, it is the particularly aggressive strength of the shortwave in the northern stream with the 12z NAM that makes it a clear outlier. As such will favor removal of the NAM across the Plains into the West after about 17.00z Monday and limit the 00z UKMET influence across the Snake River Plain into the Great Basin/Southern Rockies about 17.12z in the preferred blend. Still these are fairly small differences so the confidence is fairly high in preference throughout the forecast period. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Gallina