Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1142 AM EDT Wed Mar 27 2019 Valid 12Z Sat Mar 30 2019 - 12Z Wed Apr 03 2019 ...Overview and Weather Highlights/Hazards... Upper ridging over western Canada will refocus into Alaska to favor troughing through central/eastern Canada and the Upper Midwest/Great Lakes/Northeast. A lead low pressure system will exit through the eastern Great Lakes/St. Lawrence Valley this weekend as the trailing cold front traverses the s-central and eastern U.S., lingering across Florida and the Gulf of Mexico. This system may bring a variety of weather including some weekend snow from the upper Great Lakes to northern New England and moderate rainfall and convection ahead of and along the front. Above average temperatures preceding the front will be replaced by cooler than average temperatures that will moderate over the following few days. A series of southern stream Pacific shortwaves will progress through the West/Southwest then eastward across the U.S. southern tier. This may invigorate Gulf of Mexico frontal wave genesis next week depending on exact timing/strength of the feature aloft and offshore conditions. Rainfall may be enhanced over parts of Florida northeastward along the GA/SC/NC coast, but could also stay just offshore. Upstream, another system will push into the West Coast early next week which may result in a bit cooler temperatures amid periods of moderate rain and heavier elevation snows from the Northwest to the northern Rockies then eventually onto the Plains. ...Guidance Assessment/Preferences... The latest 06Z GFS/00Z ECMWF and 06Z GEFS/00Z ECMWF ensemble means seem to offer reasonably similar larger scale pattern evolutions, but less than stellar consistency with stream interactions and timing/strength of a multitude of smaller-scale systems embedded within the flow. Preferred a composite blend to mitigate this with a majority deterministic blend to start, transitioning to nearly a 50/50 deterministic/ensemble blend next Wed. This offered a good starting point for the exiting system this weekend where the models have come into better agreement as well as over FL and off the SE coast next Tue/Wed where the 06Z GFS was preferred over the 00Z ECMWF (perhaps too far east) but confidence remained lower than average there given mixed ensemble trends. Fracasso/Schichtel Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices are 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 https://www.wpc.ncep.noaa.gov/heat_index.shtml