875 FXUS02 KWBC 121918 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 318 PM 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... ...Broad frost/freeze threats across the northern/central U.S. late week into early next week... ...Overview... An upper low lingering over the Intermountain West will allow for moisture from Simon to stream northward, continuing to bring an expansive area of rain and thunderstorms across the central U.S. into Thursday. A downstream ridge 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. The energy from the Intermountain West 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. A strong cold front and chilly surface high pressure behind it will bring frost/freeze concerns to broad areas pressing east across the Plains, Midwest, and East through the period. ...Guidance/Predictability Assessment... Model guidance continues to show good agreement on the evolution of the upper low over the West after Thursday, with some energy combining with a strong shortwave moving southeast into the north- central U.S. to develop an amplified trough over the Great Lakes late week, and some energy held back across the Southwest as a weak upper low. The northern trough will support a strengthening surface low ahead of it, which shows good 12Z model agreement atop the Lower Great Lakes early Friday and over Atlantic Canada Saturday. The trough should track through the Northeast over the weekend, with only minor timing differences. Models continue their reasonably good agreement as ridging stretches across the Great Basin north of the upper low and across the Southern Plains late week into the weekend. Shallow troughing looks to move through the northern tier/southern Canada over the weekend with just minor timing and depth spread in the guidance. Then a trough is forecast to deepen in the Eastern Pacific and move toward or into the West Coast by the end of the period Monday. This once again shows a little model spread, but nothing out of the ordinary for the late medium range period. Good model agreement with the large scale pattern allowed the WPC forecast to use a multi-model deterministic/AIFS blend for much of the period, with some minimal ensemble mean inclusion. 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 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 to Mid-Mississippi Valley ahead of a cold front, and a WPC Slight Risk area is in place for the Thursday Excessive Rainfall Outlook. Some heavy rain may linger Friday in the southern High Plains. Farther north, areas of rain are forecast to stretch from the north-central U.S. into the Northeast Thursday and Friday with a surface low. The pattern will be favorable for lake effect/enhanced rain and even snow across the Great Lakes region to Interior Northeast through Friday-Saturday, along with upslope precipitation in the Appalachians. High winds are possible behind the surface low/cold front track in the Plains Thursday, shifting east across the Great Lakes Friday, into the higher elevations of the Northeast Saturday, and also behind the tail end of the front in the Southwest to southern High Plains. Showers and storms are possible in Florida, with amounts potentially increasing by the weekend with the front passing through. Elsewhere, the Pacific Northwest should see increasing precipitation chances into Sunday ahead of an upper trough. But overall a drier pattern is in store by the weekend into early next week, compared to the busy period lately. 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. Then Canadian high pressure is forecast to gradually track across the country behind the cold front late week into the weekend, cooling temperatures for the central and eastern U.S. and providing fairly broad frost/freeze threats. Meanwhile, the West Coast could see above normal temperatures, including some highs near and above 90 for parts of coastal California again by late week. Above average temperatures are likely to spread into the north-central U.S. over the weekend. Tate/Santorelli 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 $$