Extended Forecast Discussion NWS Weather Prediction Center College Park MD 420 PM EDT Thu Jun 04 2020 Valid 12Z Sun Jun 07 2020 - 12Z Thu Jun 11 2020 ...Gulf Coast to Mid-South Excessive Rainfall Threat with Tropical Storm Cristobal... ...Overview and Guidance/Predictability Assessment... The ECMWF and the GFS continue to be fairly clustered with the evolution of the western trough/central U.S. ridge. The CMC has a similar solution initially, but then quickly becomes out of phase by Tuesday. To maintain continuity from the previous forecast, and the latest official track for Cristobal from NHC, the bulk of the blend comprised of the 00Z ECMWF/ensemble means, 00Z/06Z GFS/ensemble means. ...Weather/Hazard Highlights... An amplified, mid-to-upper level trough will be present over the West through Tuesday before it tracks into the Plains Wednesday and beyond. It is progged to be 2-2.5 sigma deeper than climatology for early June; which will allow the daily temperatures to be noticeably cooler across the Great Basin with highs generally in the 50/60s and lows in the upper 20s/low 40s as a wavy frontal system pushes eastward. Locally enhanced precipitation is possible along and behind the system across the unsettled West to include some elevation snows from the Cascades to the Northern Rockies given trough depth. Temperatures will rebound as the trough shifts into the central U.S. Temperatures across the Southern High Plains will mainly be in the 90s/low 100s with 80s/90s elsewhere early in the week- only cooling 5-10 degrees by the end of the extended period. Deep tropical moisture streaming northward ahead of tropical cyclone Cristobal this weekend will increase the threat for excessive rainfall and flash flooding along the Gulf Coast. As Cristobal moves inland it will spread heavy rainfall with it but will quickly encounter a frontal zone. This tropical moisture will focus heavy rainfall along the track from the lower-mid MS Valley to the OH Valley/Great Lakes early-mid next week as the system undergoes extratropical transition. The western extent of enhanced moisture and rainfall continues to be a bit uncertain, especially across the Upper Midwest; however as the front progresses moderate rain will impact the eastern states later in the week. Guidance continues to suggest that another trough/closed low will setup near the Pacific Northwest by the end of the extended period which may bring another round of precipitation and cooler temperatures to parts of the West. Campbell/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 Southeast, the Lower Mississippi Valley, the Southern Plains, and the Tennessee Valley, Sun-Mon, Jun 7-Jun 8. - Heavy rain across portions of the Central Plains, the Lower Mississippi Valley, the Northern Plains, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southern Plains, and the Ohio Valley, Tue-Wed, Jun 9-Jun 10. - Heavy rain across portions of the Southeast, the Lower Mississippi Valley, and the Tennessee Valley, Wed, Jun 10. - Severe weather across portions of the Upper Mississippi Valley and the Northern Plains, Sun, Jun 7. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern Plains, the Northern Rockies, the Middle Mississippi Valley, the Mid-Atlantic, the Upper Mississippi Valley, the Southeast, and the Great Lakes. - Flooding likely across portions of the Middle Mississippi Valley. - Much above normal temperatures across portions of the Central Plains, the Northern Plains, the Central Rockies, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Southern Plains, Sun-Mon, Jun 7-Jun 8. - Enhanced wildfire risk across portions of the the Central Plains, the Central Rockies, the Central Great Basin, the Southern Rockies, the Southern Plains, and the Southwest, Sun, Jun 7. 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