Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 243 AM EDT Sun Mar 31 2019 Valid Mar 31/0000 UTC thru Apr 03/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation With Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Deep trough lifting through the Northeast... ...Cold front crossing the Eastern Seaboard... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The models show very good agreement with the details of the deep upper trough lifting up across the Northeast through Sunday, along with the attendant cold front which will cross the Eastern Seaboard. A general model blend will be preferred as a result. ...Four Corners to Southern Plains trough/closed low... ...Reaching the Gulf Coast/Southeast by Mon/Tues... ...Cyclogenesis near the Southeast Coast by Tues... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/UKMET/ECMWF blend Confidence: Average A trough and weak associated closed low over the Four Corners region will eject southeast across the southern Plains through Monday. On Tuesday, the energy will be traversing the Gulf Coast states and moving toward the Southeast. This will drive cyclogenesis along a frontal zone draped from the eastern Gulf of Mexico northeast across the FL Peninsula and up offshore the Carolinas. The dominant area of low pressure is expected to emerge just offshore of the Southeast near coastal areas of northeast FL with low pressure then lifting northeast offshore of the Carolinas by early Wednesday. The 00Z NAM is the strongest solution with the closed low/trough that ultimately swings through the southern Plains and it hangs onto stronger height falls as it crosses the Gulf Coast states and Southeast U.S. which helps to drive cyclogenesis that tucks in closer to the East Coast on Tuesday. The NAM is an outlier solution though as the global models are all farther east with the low track relative to the East Coast. However, the 00Z CMC did trend a bit farther west and is now only a little east of the NAM. The 00Z UKMET trended farther west from its previous run and is now in rather good agreement with the 00Z GFS/ECMWF solutions which are clustered east of the CMC solution. There has been some convergence in the guidance with this cycle, but the NAM/CMC solutions are still overall west of the model consensus and the GEFS/ECENS means. While there are still some members that support a farther west track, the better support remains for a solution farther offshore. Thus the preference will be toward a blend of the GFS, UKMET and ECMWF. ...Trough/Low approaching the West Coast on Mon... ...Surface low approaching the Pacific Northwest... ...Energy reaching the Four Corners by Wed... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/UKMET/ECMWF blend Confidence: Slightly above average The guidance depicts a fairly compact closed low approaching northern CA by late Monday which will be gradually opening up into a trough axis Monday night through early Tuesday while advancing inland. By Wednesday, this open trough will reach the Four Corners region. There will also be a wave of low pressure focused a bit farther north that will be approaching coastal areas of the Pacific Northwest and also under the influence of a northern stream trough/closed low west of Vancouver Island. The 00Z NAM is overall a tad stronger than the global model suite with the height falls crossing northern CA and toward the Four Corners region, although the 00Z CMC is the weakest of the global models. Regarding the surface low, the guidance is actually fairly well clustered with modest spread regarding the track of it. Overall, there is better ensemble support for a consensus of the 00Z GFS/UKMET/ECMWF solutions, and so a blend of these models will be preferred. ...Upper trough over the Northern Plains/Midwest Tues... ...Surface cold front crossing the Midwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The guidance support the intrusion of a new northern stream trough digging down over the northern Plains and Midwest by Tuesday along with a cold front. There is reasonably good model agreement with the height falls including the details of a cold frontal passage across the Midwest and with surface low pressure over south-central Canada. Based on better convergence of the guidance with this cycle, a general model blend will be preferred. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Orrison