Extended Forecast Discussion NWS Weather Prediction Center College Park MD 305 PM EDT Fri Jun 05 2020 Valid 12Z Mon Jun 08 2020 - 12Z Fri Jun 12 2020 ...Lower Mississippi Valley Heavy Rainfall Threat early next week from Cristobal... ...Overview... The synoptic pattern will remain amplified through this coming week. The western trough will progress through the central U.S. while tropical cyclone Cristobal moves inland over the northern/northwest Gulf Coast Monday and then gets caught up in the northern stream and moves toward the Northeast. Off the East Coast, a trough will likely split off an upper low that may get wrapped back toward the Mid-Atlantic/Northeast as the "ex-Cristobal"-containing front heads to the coast. Late in the period, another upper low will tracks toward the Northwest bringing another round of precipitation and cooler temperatures to parts of the West. ...Guidance/Predictability Assessment... The global guidance and the ensemble means are fairly clustered initially with the timing and evolution of the longwave trough and associated cold front passing through the central U.S. The 15Z NHC track has Cristobal moving onshore over central Louisiana then tracking north through Arkansas/Missouri before curving northeast toward the Great Lakes. A combination of the ECWMF/means, GFS/means, CMC and UKMET provided a close solution to the official track through Wednesday. Beyond this point the model spread and forecast uncertainty increases. ...Weather/Hazard Highlights... The deep trough across the West in the beginning of the extended will support temperatures of 10 to 20 degrees cooler than average for early June- with snow possible at a few higher elevation locations (Glacier Nat'l Park and Yellowstone). Also, with the ridge over the central U.S. there will continue to be 10+ degrees warmer temperatures from the Southern High Plains to the Ohio Valley ahead of the front/Cristobal. Rainfall may be enhanced along/ahead of the front over/east of the Plains into the Upper Midwest and just ahead of Cristobal as moisture axes interact/combine ahead of a 100kt jet. Several inches of rain is expected along the track of Cristobal and the threat for flooding will be elevated. By later in the week, rainfall amounts may decrease as the moisture source gets thinned and high pressure builds in from the northwest. Lighter rain is forecast for the Pacific Northwest through the week. Campbell 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