Extended Forecast Discussion NWS Weather Prediction Center College Park MD 317 PM EDT Thu May 02 2019 Valid 12Z Sun May 05 2019 - 12Z Thu May 09 2019 ...Weather Highlights/Threats... An area of enhanced rainfall is expected from the northern Mid-Atlantic to southern New England as the leading low moves offshore. The trailing cold front will provide a focus for showers and thunderstorms to develop across the Southeast, Gulf states and the Southern Plains. Rainfall intensity will likely become heavy at times, especially over the Southern Plains/Lower Mississippi Valley. Ridging aloft will remain anchored over the northeastern Pacific which will keep drive split flow over the Lower 48 next week. An unsettling and initially closed southern stream low will work into California and the Southwest as a series of cooling and precipitation focusing northern stream systems skirt along the US/Canadian border. Scattered showers and some convection will spread across the Great Basin/Rockies. The precipitation is anticipated to be mostly near the mid-to-high terrain locations. Some snow may be possible at the highest elevations, but some valley rain as well. Additionally, this synoptic setup will be favorable for periods of organized strong convection with a cell training/excessive rainfall/runoff threat as a series of hard to time northern and southern stream impulses eject over the east-central U.S. over top a building upper ridge over the Deep South. Systems may be primed to periodically tap deepening moisture and instability pooled by return Gulf of Mexico inflow into two surface frontal systems/enhanced baroclinic zones. ...Guidance/Predictability Assessment... The latest run of guidance is maintaining the overall pattern of a longwave trough setting up over the West/Southwest and ridging in over the Southeast; with an improved clustering with the shortwaves/lows in the Southern Plains, Mid-Atlantic and central Canada. The WPC medium range product suite was composed from a blend of the 06Z GFS/00Z ECMWF/00Z UKMET initially with more weighting of the 06Z GEFS Mean incorporated by the end of the extended period. Campbell Hazards: - Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Tue-Wed, May 7-May 8. - Heavy rain across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, the Southern Plains, the Ohio Valley, and the Tennessee Valley, Thu, May 9. - Severe weather across portions of the Central Plains, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Northern Plains, Mon, May 6. - Flooding possible across portions of the Central Plains, the Lower Mississippi Valley, the Great Lakes, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southern Plains, and the Ohio Valley. - Flooding occurring or imminent across portions of the Central Plains, the Lower Mississippi Valley, the Northern Plains, the Great Lakes, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southern Plains, and the Ohio Valley. - Flooding likely across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley. 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