Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 408 PM EDT Sat Sep 18 2021 Valid 00Z Sun Sep 19 2021 - 00Z Tue Sep 21 2021 ...There is a Slight Risk of excessive rainfall over parts of the Pacific Northwest/Northern California and the Tennessee Valley/Southeast through Sunday morning... ...Temperatures will be 10 to 25 degrees above average over parts of the Upper Midwest, while temperatures will be 10 to 20 degrees below average over parts of the Pacific Northwest/Northern Rockies... ...There is a Critical Risk of fire weather over parts Northern Rockies/Northern High Plains into parts of the Northern Intermountain Region/Great Basin through Sunday morning... An upper-level low over the Lower Mississippi Valley and tropical moisture over the Tennessee Valley/Southeast will produce showers and thunderstorms over the region through Monday. Some of the Thunderstorms will produce heavy rain. Therefore, the WPC has issued a Slight Risk of excessive rainfall over parts of Tennessee Valley/Southeast through Sunday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable. The excessive rainfall threat will continue over parts of the Tennessee Valley on Sunday into Monday morning. Meanwhile, moisture flowing into the Pacific Northwest will slowly weaken overnight Saturday. The moisture will produce rain over parts of the Pacific Northwest/Northern California into parts of the Northern Intermountain Region, ending overnight Sunday. The rain may be heavy at times. Therefore, the WPC has issued a Slight Risk of excessive rainfall over parts of Pacific Northwest/Northern California through Sunday morning. The threat of excessive rainfall will be over by Sunday morning. However, the system associated with the rain will move eastward into the Northern Plains by Monday, producing rain and in a few of the highest elevated areas, wet snow. As the system moves out of the Mountains onto the plains, Showers and thunderstorms will develop over parts of the Upper Midwest on Monday. Furthermore, dry conditions and gusty winds with the system led to a Critical Risk of fire weather over parts of Northern Rockies/Northern High Plains into parts of the Northern Intermountain Region/Great Basin through Sunday morning. Therefore, Red Flag Warnings are out for parts of northern Nevada, southeastern Oregon, southern Idaho, Montana, Wyoming, and parts of the Northern Plains. Additionally, temperatures will be 10 to 25 degrees above average over parts of the Upper Midwest, while temperatures will be 10 to 20 degrees below average over parts of the Pacific Northwest/Northern Rockies. Ziegenfelder Graphics are available at www.wpc.ncep.noaa.gov/basicwx/basicwx ndfd.php