Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 408 AM EDT Tue Aug 17 2021 Valid 12Z Tue Aug 17 2021 - 12Z Thu Aug 19 2021 ...HIGH Risk of flash flooding in place today/tonight as Fred moves northward and spreads very heavy rainfall and potential for landslides to the Southern Appalachians... ...Heavy rainfall and scattered flash floods are also possible across much of the eastern U.S. as tropical moisture streams north... ...Cooler and wetter conditions are likely for the Northwest behind a potent cold front, with warm temperatures and Elevated to Critical fire weather conditions ahead of it... ...Monsoonal moisture will cause additional showers and thunderstorms as well as the threat of flash flooding for the Southwest into Utah through midweek... As Fred is now onshore, its winds will continue to weaken as it moves northward across the eastern U.S. However, more hazards are to come with Fred, as extremely heavy rainfall of several inches (10+ inches in localized areas) is forecast to fall today across the Southern Appalachians, given Fred's energy and moisture as well as a weak upper-level trough moving toward the region. This area is particularly sensitive to heavy rainfall because of the varying terrain, and widespread flash flooding is expected, along with the possibility of landslides particularly in the mountains of North Carolina and the Blue Ridge Escarpment. A High Risk of excessive rainfall has been raised for this area today into tonight. In addition, a few tornadoes are possible for the Southern Appalachians into parts of the Piedmont. Trailing bands of rain with Fred could also occur over northern Florida and into South Carolina today. Meanwhile, tropical moisture streaming northward across much of the East feeding into a weak frontal system ahead of the aforementioned trough will lead to widespread rain and thunderstorms across the Central/Northern Appalachians and parts of the Mid-Atlantic into New York over the next couple of days. Scattered flash floods are possible in these areas and are under Slight Risks of excessive rainfall through Wednesday. A potent cold front pushed by an upper-level low will move through the Northwest over the next couple of days, significantly cooling temperatures there. High temperatures are forecast to drop to 20 to 30 degrees below normal in the Northern Rockies by Wednesday, with highs in the 50s. However, temperatures should remain hot ahead of the front, with a couple more days of 100+ temperatures expected for the Northern Plains. Areas such as the Central Great Basin should see warmer than normal temperatures today followed by below normal highs by Wednesday as the cold front approaches. Additionally, Elevated to Critical fire weather conditions are a threat again today, along with the potential for additional fire ignitions from dry thunderstorms. Red Flag Warnings are in place from portions of California through the Central Great Basin into the Northern High Plains. Rain showers are also likely with this system in the West, mainly along and behind the cold front, while in the meantime monsoonal moisture will continue flowing into the Southwest toward Utah. With rainfall totals over an inch in some areas with locally higher amounts, Marginal Risks of excessive rainfall are in place across portions of the Four Corners states northward into the Northern Rockies and eastward to Texas over the next couple of days, along with embedded Slight Risks over much of Utah, which could be particularly hard hit and tends to be sensitive to rain causing flash flooding. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php