Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 452 AM EDT Sat Oct 03 2015 Valid 12Z Sat Oct 03 2015 - 12Z Mon Oct 05 2015 ...Heavy rain and flash flooding expected for parts of the Southeast and the Southern Appalachians... ...Temperatures will be 10 degrees below average from the Northeast to the Western Ohio Valley/Central Gulf Coast... A strong ridge over a vast majority of the central/eastern CONUS will keep the surface frontal system slow moving through the Intermountain West and Northern Plains. It will also aid in maintaining a quasi-stationary front along offshore of the East Coast. Moisture from the Gulf of California and the Western Gulf of Mexico will advect toward the High Plains, and in combination with upper-level energy embedded in a deep upper-level trough over the Rockies, will aid in producing rain over parts of the Northern/Central High Plains/Rockies through Sunday, while showers and thunderstorms will develop over part of the Southern Rockies and the Southern High Plains. Most of western Montana and northwest Wyoming will have mix of rain and snow before it transitions to mostly snow by Sunday. Local amounts of 2 to 4 inches are forecast for those areas. Additionally, embedded upper-level energy over the Pacific Northwest will move southward to Southern/Central California by Sunday morning. A large swath of the Eastern Seaboard will continue to have periods of heavy rain and cooler temperatures through Monday morning. The latest track of Hurricane Joaquin is forecast to remain over the Atlantic Ocean; however continuous moisture streaming over the quasi-stationary boundary will result in widespread rain. Refer to the National Hurricane Center for the latest information on that system. Rainfall totals are forecast to range greatly over the next three days. Most of the Mid-Atlantic will have additional amounts up to 1 inch. The Central/Southern Appalachians and the Carolinas could see 2 to 10 inches, with isolated amounts in excess of 15 inches. Much of the region is water logged and cannot accommodate additional moisture. The risk of flash flooding and river flooding is high across the Mid-Atlantic and Southeast states. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php