Extended Forecast Discussion NWS Weather Prediction Center College Park MD 150 AM EST Sun Feb 03 2019 Valid 12Z Wed Feb 06 2019 - 12Z Sun Feb 10 2019 ...Overview... Positive height anomaly near the Gulf of Alaska will favor western CONUS troughing Wed-Sun and broad SW upper flow in the eastern states. Subtropical upper high will drift out of the Bay of Campeche and into the Florida Straits which will largely keep the storm track through the Great Lakes and St. Lawrence Valley. ...Guidance/Predictability Assessment and Preferences... Upstream Pacific flow and northern/southern stream separation in the West continued to be poorly resolved by the models/ensembles with noticeable run-to-run changes. The ECMWF and its ensembles have been quite different than the GFS and its ensembles while the Canadian and its ensembles mostly clustered near the ECMWF ensembles. Preferred the cluster near the ECMWF ensemble mean which showed a bit quicker exit of the trough out of the Rockies late Wed/early Thu and no subsequent surface low development out of the lower MS Valley next Fri/Sat. This maintained good continuity from the previous shift. Weather Highlights/Hazards... Above average temperatures in the Southeast/East (with record highs possible) will be replaced by nearer to average temperatures as the cold front clears the East Coast, but not through Florida thanks to the strong upper ridge. In the northern tier from MT to the Upper Midwest, temperatures will remain well below average behind an arctic front that will get hung up near the Divide (but still bring cold air to the Pacific Northwest via northern stream height falls). Storm track will favor snow and lower elevation rain exiting the Rockies Wed and spreading across the Plains to the Ohio Valley (as a second wave of precipitation) Thursday with increased snow around the north/northwest side of the developing surface low. Warm-sector rain may be locally modest through the lower MS Valley/ArkLaTex but trend lighter to the east as the upper ridging keeps the best dynamics well to the north. With the favored track through Lake Ontario, rain will spread through the mid-Atlantic into the Northeast except interior Maine and northern NH/VT/NY. Once the low pulls away, lake-effect snow will resume for at least Friday into Saturday as the sfc high slips southeastward. Fracasso WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation and winter weather outlook probabilities are found at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4