555 FXUS02 KWBC 070709 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 309 AM EDT Wed Oct 7 2026 Valid 12Z Sat Oct 10 2026 - 12Z Wed Oct 14 2026 ...Tropical system will bring heavy rainfall and flash flooding across parts of the Southeast into the Mid-Atlantic through the weekend... ...Pattern Overview... The Gulf tropical cyclone will lift northeastward bringing chances for excessive rainfall across portions of the Southeast into the Ohio Valley/Mid-Atlantic through the weekend. A amplified western trough will interact with Hurricane Rachel, bringing widespread rain across the Southwest into the Great Basin and Intermountain West/Rockies. Chances for snow increases for high elevations over the northern Rockies through the weekend. ...Guidance/Predictability Assessment... The models continue to have decent agreement on the western trough as it continues to deepen through the weekend, while interacting with moisture from Hurricane Rachel. Uncertainty increases in regard to the exact amplitude and progression of embedded shortwaves, especially towards Monday into Tuesday. Another area of uncertainty remains with the tropical system over the Gulf as it begins to move inland. The greatest uncertainties among the models is the exact track and the magnitude and extent of the tropical moisture and associated heavy rainfall. The AI guidance seemed to have a better handle on the storms track as it moves inland and the ensemble means helped smooth out extreme rainfall amounts. Therefore, the forecast incorporated a multi-model blend through the first portion of the period, with heavier weight on the ensemble means and AI guidance towards early next week. ...Weather/Hazards Highlights... The primary concern for the upcoming weekend will be the ongoing hydrological effects of the tropical system that crosses the northern Gulf Coast late this week. Even as the cyclone weakens inland, a deep plume of Gulf moisture and a broad circulation will support periods of moderate to heavy rainfall across portions of Southeast northward into the Mid-Atlantic and Ohio/Tennessee Valley. Locally excessive rainfall remains possible where training occurs and/or where the remnant circulation interacts with frontal boundaries. Antecedent wet soils from previous rainfall will increase the potential for renewed flooding, especially over portions of the Southeast into the Carolinas and Mid-Atlantic, which is reflected in WPC Excessive Rainfall Outlook for Day4/Saturday. The system will track northeastward Sunday into Monday, bringing chances for heavy rainfall across portions the Ohio Valley/Great Lakes into the Mid- Atlantic and Northeast. A combination of anomalous moisture, low- level inflow, and forcing should support a period of heavy rainfall, leading to flooding concerns, especially over portions of the Mid-Atlantic and Northeast coastal areas. Refer to NHC.gov for more information and updates on the tropical system. The tropical moisture plume and associated frontal system should continue northeastward into Monday, bringing additional rainfall over the Northeast. Over western U.S., the upper trough will bring periods of rain that will impact the Pacific Northwest and Intermountain West, with rain spreading into the northern/central Rockies as the trough digs southeastward. Snow levels should lower as colder air overspreads the region, resulting in accumulating snow across higher elevations over the northern Rockies/Intermountain West. As the trough deepens and interacts with tropical moisture from Hurricane Rachel, chances for widespread heavy rainfall and localized flooding increases over the Southwest into the Great Basin and central Rockies through the weekend. Temperatures should trend downward behind the advancing western trough over the Northwest into the north/central Plains through Wednesday. Periods of rain will continue along the frontal boundary for the Southwest into the Plains and Upper Midwest from Monday through Tuesday. Oudit Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw $$