Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 425 PM EDT Tue Aug 17 2021 Valid 00Z Wed Aug 18 2021 - 00Z Fri Aug 20 2021 ...HIGH Risk of flash flooding in place today/tonight over Western North Carolina as Fred moves northward and spreads very heavy rainfall; potential for landslides in the Southern Appalachians... ...Heavy rainfall and scattered flash floods are also possible across much of the eastern U.S.... ...Cool and wet conditions are likely for the Intermountain West 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... This afternoon, Tropical Depression Fred continues a north-northeastward track through the Southeast, and is approaching the spine of the Appalachian Mountains close to the Georgia-North/South Carolina border. A slew of hazardous weather accompanies Fred, including extremely heavy rainfall and severe weather. A High Risk of excessive rainfall remains in effect over western North Carolina since the initial issuance this morning, as widespread rain accumulations of 4 to 8 inches (with isolated storm totals of 10 inches) are expected over the Southern Appalachians through today. This area is particularly sensitive to heavy rainfall due to the varying terrain and inundated ground from recent heavy rains in the region. Severe, widespread flash flooding is anticipated, and numerous Flash Flood Warnings cover the region as bands of training thunderstorms overtake the area. In addition to flash floods, the heavy rain will bring an increased risk of landslides in the mountains of North Carolina and the Blue Ridge Escarpment. Severe weather also remains a distinct possibility over parts of Georgia, the western Carolinas, and southwestern Virginia where an Enhanced Risk of severe weather is highlighted by SPC, primarily for the threat of several tornadoes. 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 a weak upper-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. Through Friday, 2 to 4 inches of rain with isolated totals of 6 inches are expected over the Central Appalachians/Mid-Atlantic as remnants of Fred move north-northeast. Ahead of the anticipated scattered flash floods later this week, Flash Flood Watches are already in effect over the aforementioned areas in the Appalachians, Mid-Atlantic, and Northeast. In the West, a potent cold front pushed by an upper-level low will move through the Intermountain West 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. Ahead of the front, 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 as dry and windy conditions align with the movement of the strong front. Related to the fire activity, poor air quality continues over the northern Great Basin, Rockies, and Central California, where Air Quality Alerts cover the region. Rain showers are also likely with this system in the West along and behind the cold front, while monsoonal moisture pools ahead of the boundary in the Southwest around Utah. The approaching front will interact with the monsoonal moisture to support a severe weather threat over Central Utah, where SPC has highlighted a Slight Risk for isolated severe wind gusts. Moreover, rainfall totals over an inch with locally higher rainfall amounts may produce isolated instances flash flooding across portions of the Four Corners states northward into the Northern Rockies, and eastward to Texas over the next couple of days. Embedded Slight Risks of excessive rainfall are highlighted over portions of Utah, southern Arizona, and Central Texas through Wednesday where the flash flood threat is more focused. Asherman/Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php