Extended Forecast Discussion NWS Weather Prediction Center College Park MD 347 PM EDT Tue Mar 26 2019 Valid 12Z Fri Mar 29 2019 - 12Z Tue Apr 02 2019 ...Overview and Weather Highlights and Hazards... Strong upper ridging initially over British Columbia will drift northwestward into Alaska which favors broad troughing through central/eastern Canada and through the Upper Midwest/Great Lakes/Northeast. Underneath the western Canadian high, weaker shortwaves will drop through the Four Corners region and eventually turn the corner across Texas early next week and head eastward, possibly invigorating a surface boundary in the Gulf. In the northern stream, low pressure will exit through the eastern Great Lakes/St. Lawrence valley this weekend as the tail-end of its cold front lingers across Florida. This system will bring a variety of weather to the central/eastern states Fri-Sun: severe weather for portions of Oklahoma on Friday (see SPC for more info), well above average temperatures to the Northeast/Mid-Atlantic Saturday, well below average temperatures behind the front (especially over the Southern Plains into the Midwest on Sunday), snow across the central Plains Fri/Sat, and locally heavy rainfall ahead of and along the front initially in the Midwest to Northeast but then perhaps over Florida next week. The west will see another system push into WA/OR early next week with only light to modest amounts of rain/snow. ...Guidance Assessment/Preferences... Latest deterministic models were reasonably well-clustered for the Fri-Sun period as the eastern system lifts into southeastern Canada and the western shortwaves dip into the southern Rockies. The 06Z GFS and 00Z UKMET became quicker/flatter than the 00Z GFS/ECMWF/Canadian late Sat into Sun over the Four Corners but weighted the slower solutions more than the quicker ones by about a 3:1 ratio given the good ensemble clustering but still uncertain evolution prior. Exodus of the eastern system was uncertain over New England late Sun/early Mon as the GFS/Canadian runs were quicker than the ECMWF/UKMET with a possible wave along the front. For now, opted to keep the front more progressive given the propensity of the ECMWF to be too slow, but many ensemble members showed such development. Trended toward more ensemble weighting by next Mon/Tue with details added per the ECMWF/Canadian off the West Coast with an incoming system that the GFS runs have lost in recent runs. Ensemble members strongly show a coherent low pressure (albeit only of modest depth) moving toward the Washington coast around next Tuesday with the front inland into the Great Basin and central California. Fracasso 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 Hazards: - Heavy precipitation across portions of the Pacific Northwest, Mon, Apr 1. - Heavy rain across portions of California and the Pacific Northwest, Mon, Apr 1. - Heavy rain across portions of the Middle Mississippi Valley, the Great Lakes, the Ohio Valley, and the Upper Mississippi Valley, Fri-Sat, Mar 29-Mar 30. - Heavy snow across portions of the Central Rockies, the Central Plains, and the Northern Plains, Fri, Mar 29. - Severe weather across portions of the Southern Plains, Fri, Mar 29. - Flooding possible across portions of the Central Plains, the Middle Mississippi Valley, and the Northern Plains. - Flooding occurring or imminent across portions of the Central Plains, the Lower Mississippi Valley, the Northern Plains, the Tennessee Valley, the Middle Mississippi Valley, the Upper Mississippi Valley, the Great Lakes, and the Ohio Valley. - Flooding likely across portions of the Middle Mississippi Valley, the Upper Mississippi Valley, and the Northern Plains. - High winds across portions of the Central Plains and the Southern Plains, Sat, Mar 30. 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