Extended Forecast Discussion NWS Weather Prediction Center College Park MD 339 PM EDT Tue Jun 18 2019 Valid 12Z Fri Jun 21 2019 - 12Z Tue Jun 25 2019 ...Weather Highlights/Threats... An unsettling southeast Canada/Northeast U.S. upper trough and coastal low will support lingering wrapping moisture/rainfall into northern New England Friday into Saturday. The closed 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 into early next week. Expect hot warm sector temperatures under this ridge including a risk of record warm minimum values mainly for the eastern southern Plains and lower MS Valley. This ridge builds ahead of a series of upstream troughs that drift/reform from the Northwest/West to the Rockies and Plains/south-central Canada. The systems present an emerging threat of strong to severe/MCS convection and locally heavy rains with frontogenesis/cyclogenesis, pooling moisture/instability and repeat cells. There is also a risk of some northern Rockies June snows. ...Guidance/Predictability Assessment... The WPC medium range product suite was derived from a composite blend of compatable guidance from the 06 UTC GFS and 00 UTC ECMWF/Canadian/UKMET days 3-5 then GFS/ECMWF and GEFS/ECMWF ensemble guidance days 6/7 in a timeframe with increased but manageable forecast spread. This maintains good WPC continuity, albeit with most uncertainty still associated with the focus for localized summertime convective 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 Plains, the Lower and Mid Mississippi Valley, into the the Tennessee Valley, parts of the Ohio Valley, Central Appalachians and the Great Lakes, Sun-Mon, Jun 23-Jun 24. - Heavy rain across portions of the Central Plains, the Middle Mississippi Valley into the Upper Midwest and parts of the Great Lakes as well as the Ohio Valley, Fri-Sat, Jun 21-Jun 22. - Severe weather across portions of the Central Plains, the Middle Mississippi Valley, the Upper Midwest, and the Northern Plains, Fri, Jun 21. - Flooding possible across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley. - Flooding occurring or imminent across portions of the Central Plains, the Lower and Middle Mississippi Valley, and the Ohio Valley. - Flooding likely across portions of the Southern Plains, the Central Great Basin, and the Northern Great Basin. - Excessive heat across portions of southern Texas, Fri-Tue, Jun 21-Jun 25. - Excessive heat across portions of the Mid-Atlantic, Mon-Tue, Jun 24-Jun 25. - Much below normal temperatures across portions of the northern and central Rockies, the northern High Plains, and into parts of the Great Basin, Fri-Sat, Jun 21-Jun 22. 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