Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 AM EDT Sat Sep 12 2020 Valid 12Z Sat Sep 12 2020 - 12Z Mon Sep 14 2020 ...There is a slight risk of excessive rainfall over parts of southern Florida... ...T. D. NINETEEN moves northwestward across southern Florida and to enter the Gulf of Mexico... ...Air quality alerts and dense smoke advisories across the Pacific Northwest, California, and parts of the Great Basin... ...Temperatures will be 10 to 15 degrees above average over parts of the interior Pacific Northwest/Northern Intermountain Region... T. D. NINETEEN is forecast to move northwestward across southern Florida to the Gulf of Mexico by Saturday evening while strengthening to a Tropical Storm. The Tropical Storm will continue to move northwestward across the Northeastern Gulf of Mexico. The system will produce heavy rain across parts of southern Florida from Saturday morning to Sunday morning. The WPC has issued a slight risk of excessive rainfall over parts of southern Florida. The heavy rain associated with the system will produce mainly localized areas of scattered flash flooding over parts of southern Florida on Saturday into Sunday morning. Please see the latest Tropical Weather Outlook from the National Hurricane Center for additional and updated information across this area. Meanwhile, a deep upper-level low over the Middle Missouri Valley will weaken and race off to the northeast to Eastern Canada by Monday morning. The developing front will extend from the Great Lakes southwestward to the Southern Plains by Sunday morning will move eastward to the Northeast/Mid-Atlantic Coast, by Monday, extending to the interior Gulf Coast States. Showers and thunderstorms will develop along and ahead of the boundary over the Great Lakes/Ohio Valley by Saturday evening. The Showers and thunderstorms will move to the Central Appalachians, Eastern Ohio Valley, and the Tennessee Valley by Sunday evening with rain moving into the Northeast. In addition, temperatures will be 10 to 15 degrees above average over parts of the interior Pacific Northwest/Northern Intermountain Region in part due to strong upper-level ridging over the West Coast. Subsiding air associated with the ridge will aid in air becoming stagnate over the region. The ongoing fires across the west have produce very poor and unhealthy air quality due to the large amounts of wildfire smoke. Therefore, dense smoke advisories and air quality alerts are posted over the Pacific Northwest, parts of California, and parts of the Great Basin. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php