Lexington, Massachusetts, USA
Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 230 PM EDT Sun Oct 11 2026 Valid 00Z Mon Oct 12 2026 - 00Z Wed Oct 14 2026 ...Post-Tropical Cyclone Isaias will bring heavy rainfall to the Eastern states... ...Tropical moisture will continue to bring heavy precipitation and flash flooding to the southwestern U.S.... ...Winter storm conditions forecast across the Northern Rockies through Monday morning... An active weather pattern will continue across the Lower 48 through Monday. Post-Tropical Cyclone Isaias is bringing widespread rainfall to the Mid-Atlantic and southern New England, with convective showers and thunderstorms extending along the Southeast Coast. Locally heavy rainfall could lead to isolated to scattered instances of flash flooding in the Mid-Atlantic. Isolated to scattered severe thunderstorms will also be possible through this evening from the Mid-Atlantic into the eastern Carolinas. Rainfall will continue across the Mid-Atlantic into Monday morning, but should gradually taper off through the afternoon as Isaias moves offshore into the Atlantic. Dry conditions will prevail across the East for the rest of the day on Monday, but precipitation chances will likely return to the Northeast on Tuesday as a frontal boundary sinks into the region. Meanwhile, tropical moisture associated with the remnants of Rachel is surging into the Intermountain West and producing heavy precipitation ahead of a deep upper low. Widespread heavy rainfall could cause numerous instances of flash flooding in the southwestern U.S., especially near steep terrain and burn scars. There is a Moderate Risk of excessive rainfall though tonight for portions of Nevada, Utah, and Arizona, and a Slight Risk for this region on Monday. Moisture extending into the northern Intermountain West encountered colder temperatures, resulting in wintry precipitation across the northern Rockies. Winter Storm conditions will be possible in this area through Monday morning, then conditions will improve as the upper low focuses over the Southwest on Tuesday. As the low shifts to the Southwest, precipitation should shift east into Wyoming and Colorado and severe thunderstorms will be possible ahead of the system over the central and southern High Plains. A temperature dichotomy will exist across the country through mid-week. Well above average temperatures are forecast to develop over much of the central and eastern U.S., with highs into the 80s and even lower 90s for portions of the Plains and Midwest. There will likely be some daily record highs that will be tied or broken. Much colder temperatures are expected across the West under the upper low, with highs generally in the 40s and 50s across the Intermountain West. Dolan/Asherman Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php