Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM 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... WPC medium range products were primarily derived from a composite blend of the reasonably well clustered GFS/ECMWF and GEFS/ECMWF ensemble means days 3-7, transitioning blend weights increasingly from the models to the ensembles amid growing forecast spread over time, especially by next Wed/Thu. This maintains good WPC continuity as well as the latest official track for Cristobal from NHC. ...Weather/Hazard Highlights... An amplified mid-upper latitude upper trough will dig inland across the West this weekend into early next week. Maximum temperatures will drop to 10-20 degrees below normal from the Intermountain West to Northern/Central Rockies 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. Pre-frontal above normal temperatures are forecast to persist in the Plains into early next week, including some maximum temperatures 15+ degrees above normal. Meanwhile, deep tropical moisture inflow will fuel a threat for excessive rainfall over the central and eastern Gulf Coast/FL ahead of Cristobal this weekend, reaching a frontal zone dropping into the Southeast. The approach and landfall of Cristobal will increasingly 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. Mid-latitude upper trough/frontal approach from the west and uncertain stream phasing may spread enhanced moisture/rainfall back into the Upper Midwest. Frontal progression should then spread moderate rains over the East late period. Upstream late period, there is a decent guidance signal supporting renewed mid-upper level trough development and approach to the West Coast mid-later next week. Expect a lead frontal push inland into the West should support an additional period of precipitation. 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 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