Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 PM EDT Fri Oct 30 2015 Valid 00Z Sat Oct 31 2015 - 00Z Mon Nov 02 2015 ...Flash flooding and severe thunderstorms possible across areas from the southern plains to the lower Mississippi valley through Saturday... ...Heavy rain possible across portions of the Pacific Northwest... An upper-level trough and associated surface low pressure system will continue to bring widespread showers and thunderstorms to the southern plains and western Gulf Coast tonight, before shifting east to the lower Mississippi valley and central Gulf Coast on Saturday. A deep plume of tropical moisture will stream northward and interact with the frontal system to generate numerous showers and thunderstorms, some of which may produce very heavy rainfall. Some areas may see multiple rounds of showers and thunderstorms. As a result, heavy rainfall amounts, and flash flooding, are possible. The threat for heavy rainfall and flash flooding will continue through tonight across portions of the southern plains and western Gulf Coast region, before shifting east into the lower Mississippi valley and central Gulf Coast on Saturday, and into portions of the Southeast on Sunday. Additionally, severe thunderstorms are possible from the southern plains into the lower Mississippi valley tonight into Saturday. Please refer to Convective Outlook products issued by the Storm Prediction Center for further details on the severe weather threat. Moisture from the system crossing the southern plains and the Southeast will also stream farther north, bringing showers to portions of the central plains and Midwest on Saturday, and into the Northwest by Sunday. Snow may mix with rain showers across portions of northern New England on Sunday. A series of upper-level disturbances along with a constant plume of moisture will continue to impact parts of the Pacific Northwest through the weekend. Rain and high elevation snow will persist through Sunday across portions of coastal Washington and Oregon. Rain and high elevation snow showers will also occur over the northern Intermountain West as the plume of moisture crosses this area, although precipitation amounts in this area will be lighter than those across the Pacific Northwest. The long duration of the rain across the Pacific Northwest will result in the potential for heavy rainfall amounts, and flooding is a possibility through the weekend. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php