Extended Forecast Discussion NWS Weather Prediction Center College Park MD 306 PM EDT Thu Jun 20 2019 Valid 12Z Sun Jun 23 2019 - 12Z Thu Jun 27 2019 ...Weather Highlights/Threats... The upper ridge redeveloping over the southeast CONUS for the rest of the work week will prime the southern Plains and lower MS Valley with heat and moisture ahead of a trough that swings across the central CONUS Sunday through Tuesday. Forcing ahead of the trough crossing the Rockies this weekend presents a threat of strong to severe/MCS convection and locally heavy rains in areas with pooling moisture/instability. The heavy rainfall focus Monday and Tuesday is forecast to be from Oklahoma across the lower MS Valley and south to east Texas. Widespread rain is also forecast across the Midwest in this time. The rainfall focus shifts to New England along a warm front lifting north ahead of the low crossing the Great Lakes Tuesday night into Wednesday night. Expect above normal temperatures (particularly for minimums) across the southern Mississippi Valley and the Southeast/TN Valley/OH Valley/Appalachians on Sunday, continuing across the Northeast through Tuesday. After initial cold in the high Plains and Rockies, temperatures moderate early next week. Then another area of warmer than normal temperatures develops as an upper ridge builds across the northern Plains through the middle of next week, with anomalies as much as ten degrees above normal by Thursday in the Dakotas and MN. A low pushing south along the Pacific Northwest coast leads to a cooling trend next week across much of the west, with widespread temps several degrees below normal, focused on across the West Coast on Wednesday, pushing inland to the Great Basin and interior Pacific Northwest on Thursday. ...Guidance/Predictability Assessment... The WPC medium range product suite was derived from a blend of the 00 UTC deterministic ECMWF/UKMET and 00 UTC ECENS/06 UTC GEFS ensemble mean guidance. The 06 UTC deterministic GFS remains in its long term bias of moving the 500 mb wave out of the central US faster than the ECMWF/UKMET (as well as the CMC) and the ECMWF and GEFS Means starting on Sunday. There is some uncertainty with the progression of this shortwave trough/low across the Great Lakes Monday and Tuesday. The 00 UTC ECMWF is more amplified with the 500 mb trough and possible embedded closed low across the upper MS Valley Mon and Great Lakes Tue that caused the ECMWF to be the slowest of the guidance envelope. Most ECMWF and GEFS members cluster in between the ECMWF and GFS, so the preferred solution has increasing weights toward the means through time. Next week, a closed low moves southeast from the Gulf of Alaska into the Pacific Northwest, coming ashore by the middle of next week. This persistent and slow moving circulation allows the deep layer ridge to rebuild over TX and NM, and then extend north into the northern Plains. There is less spread than normal for this consensus, lending the situation to a consensus based approach. Jackson 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 Middle Mississippi Valley, the Lower Mississippi Valley, the Southern Plains, and the Tennessee Valley, Sun-Mon, Jun 23-Jun 24. - Flooding possible across portions of the Central Plains, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley. - Flooding occurring or imminent across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley. - Flooding likely across portions of the Central Great Basin and the Ohio Valley. - Excessive heat across portions of the Southern Plains, Sun-Mon, Jun 23-Jun 24. - Excessive heat across portions of the Southeast and the Mid-Atlantic, Sun-Tue, Jun 23-Jun 25. - Much below normal temperatures across portions of the Southern Rockies, the Central Rockies, the Central Great Basin, the Central Plains, and the Southwest, Sun, Jun 23. 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