626 FXUS02 KWBC 120736 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 336 AM EDT Mon Oct 12 2026 Valid 12Z Thu Oct 15 2026 - 12Z Mon Oct 19 2026 ...Heavy rainfall threat for the south-central U.S. into Thursday... ...Record heat for the Mid-South and Southeast through Thursday... ...Overview... An upper low lingering over the Intermountain West will allow for moisture from ex- Simon to stream northward, continuing to bring an expansive area of rain and thunderstorms across the central U.S. into Thursday. The energy from this trough will split after Thursday, with part of it moving into the Southwest U.S. and the rest combining with strong northern stream energy from Canada. This results in a deep trough into the eastern half of the U.S. late week, shifting offshore next weekend. Before then, strong upper ridging over the south- central to southeastern U.S. early in the period should allow for much above normal to record- setting warm temperatures broadly into Thursday before modifying. ...Guidance/Predictability Assessment... Model guidance continues to show good agreement on the evolution of the upper low over the West on Thursday, with most solutions now showing a splitting of energy. Some uncertainty remains with how much energy gets left back in the Southwest, but most of the energy should get scooped up by a shortwave into the north-central U.S. with now only minor timing differences on the progression of an amplified trough through the Great Lakes and Northeast Friday and Saturday. After this, additional energy slides through south- central Canada ahead of a deeper trough into the West early next week. There is some uncertainty with the timing of this trough. With sufficient model agreement, was able to use a blend of the deterministic/AIFS guidance through Day 5. After that, increased the ensemble means to 60 percent of the total blend by Day 7 to help smooth out some of the smaller scale late period details. Overall, this approach is consistent with WPC continuity and the National Blend of Models. ...Weather/Hazards Highlights... Associated with the upper low over the West, a Plains lee low pressure system plus moisture from what is leftover from Simon streaming northward will continue to bring rain in the south- central U.S. into Thursday. Thunderstorms and heavy rain/flooding potential are likely in the Southern/Central Plains ahead of a cold front, with a WPC Slight Risk area in place for the Thursday Excessive Rainfall Outlook. Farther north, areas of rain are forecast to stretch from the north-central U.S. into the Northeast Thursday and Friday. The pattern will be favorable for lake effect/enhanced rain and possibly snow across the Great Lakes to Interior Northeast through Friday- Saturday. Gusty winds are possible especially behind the surface low track through the north- central U.S. and Great Lakes. Showers and storms could accompany the front as it pushes through Florida late week as well. Ahead of the front, temperatures in the Lower Mississippi Valley, Mid-South, and the Southeast will be well above normal and likely continue to set new daily high temperature records (upper 80s to the mid 90s) into Thursday. The trough moving into the East on Friday will moderate temperatures back towards normal. Meanwhile, the upper trough in the West will bring broadly below average temperatures there for midweek. Canadian high pressure is forecast to gradually track across the country behind the cold front late week into the weekend, cooling temperatures and providing potentially fairly broad frost/freeze threats. Meanwhile, the West Coast could see above normal temperatures, including some highs near 90 for parts of coastal California again by late week. Santorelli/Tate 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 $$