Extended Forecast Discussion NWS Weather Prediction Center College Park MD 412 PM EDT Mon Jun 17 2019 Valid 12Z Thu Jun 20 2019 - 12Z Mon Jun 24 2019 ...Weather Highlights/Threats... A dynamic southeast Canada/Northeast U.S. upper trough will tap moisture and instability to support a risk of locally heavy convective rains across the Northeast through later this week as a series of inland frontal waves try to consolidate and deepen offshore. The trough is expected to slowly give way to a warming upper ridge building from the east-central U.S./Southeast up into the Great Lakes by early next week. This ridge builds ahead of a series of upstream closed troughs that drift/reform from the Northwest to the Rockies and northern Plains/south-central Canada. These systems will present an emerging threat of locally heavy to severe convection and heavy rainfall with surface frontogenesis and cyclogenesis and moisture/instability return. Height falls also dig through an unsettled and moderated West and lead to an emerging convective rainfall potential pattern over the south-central U.S. ...Guidance/Predictability Assessment... The WPC medium range product suite was primarily derived from a composite blend of compatable guidance from the 06 UTC GFS and 00 UTC ECMWF guidance Day 3/4 (Thu/Fri). While the overall mass field pattern evolution is fairly well defined by most guidance, opted to transition to a more compatable 06 UTC GEFS and 00 UTC ECMWF ensemble blend by days 6/7 in a period of decreasing forcast predictability and model run to run continuity, especially with the focus for more localized summertime weather and hazards. 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 Hazards: - Heavy rain across portions of the Central/Southern Plains, to the Ohio Valley, Sat-Sun, Jun 22-Jun 23. - Heavy rain across portions of the Northern/Central Plains, and the Upper Mississippi Valley, Fri, Jun 21. - Heavy rain across portions of the Northeast, Thu-Fri, Jun 20-Jun 21. - Severe weather across portions of the Central Plains, the Middle/Upper Mississippi Valley, Fri, Jun 21. - Flooding possible across portions of the Central/Southern Plains, and the Ohio Valley. - Flooding occurring or imminent across portions of the Missouri/Mississippi River Basins. - Flooding likely across portions of the Southern Plains and the Central Great Basin. - Excessive heat across portions of the Southern Plains, Thu-Mon, Jun 20-Jun 24. 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