Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EST Wed Nov 13 2024 Valid 00Z Thu Nov 14 2024 - 00Z Sat Nov 16 2024 ...Heavy coastal rain and high-elevation mountain snow over the Pacific Northwest and northern California will become lighter and more scattered by Thursday, followed by moderate to heavy snow along the Sierra Nevada late Thursday to Friday... ...Locally heavy rain/flash flooding and possibly severe weather are expected across the lower Mississippi Valley as locally heavy rain and thunderstorms move across lower Ohio, Tennessee, and Mississippi Valleys through tonight... ...A rapidly developing coastal storm is expected to bring a period of gusty winds, enhanced rainfall and thunderstorms from the Carolinas to the Mid-Atlantic states Thursday night into Friday... Heavy lower-elevation rain and high-elevation mountain snow are currently in progress across much of the Pacific Northwest into northern California. Precipitation coverage and intensity will gradually decrease by tonight as the main energy of the jet stream pushes farther inland. By Thursday, another upper-level trough from the Pacific will begin to approach the West Coast. Generally light to moderate elevation-dependent rain/snow will linger across the Pacific Northwest but the precipitation will begin to expand southward into California as the upper trough and the associated cold front dip into the region. By late Thursday into Friday, a low pressure system is forecast to develop over the Great Basin. This system will bring a mix of rain and snow along with colder and windier conditions from California into the Great Basin on Friday. Highest snowfall amounts are expected along the Sierra Nevada where a foot of wet snow is possible. As an expansive high pressure system continues to provide fine weather and colder temperatures into the eastern U.S., Gulf moisture is streaming north into the lower Mississippi Valley along a weak front together with a remnant low pressure center associated with former Hurricane Rafael. This system will track northeastward and merge with another low pressure system currently moving east across the north-central U.S. The interaction of these two systems will help trigger a broad area of showers and embedded thunderstorms stretching from the Midwest/Great Lakes south through the Ohio, Tennessee, and lower Mississippi Valleys through tonight. Greater and deeper moisture content closer to the Gulf as well as some marginal instability will bring the threat for some locally heavy downpours producing a few inches of rain for the Lower Ohio, Tennessee, and Lower Mississippi Valleys, where a Marginal Risk of Excessive Rainfall (level 1/4) is in effect for some isolated flash flooding. A targeted Slight Risk (level 2/4) remains in effect from central Louisiana northeast into central Mississippi where higher confidence in greater rainfall rates and very wet antecedent conditions from prior heavy rainfall events may lead to a few more scattered instances of flash flooding. The system will continue eastward on Thursday, bringing shower and thunderstorm chances to the upper Ohio Valley, Appalachians, and the Carolinas/Southeast, while lingering across the Great Lakes. Some more moderate to locally heavy rainfall totals are most likely across the central/southern Appalachians and Carolinas where precipitation will be enhanced as a coastal storm is forecast to develop rapidly Thursday night into Friday morning near the North Carolina coast. This system will likely bring blustery winds and enhanced rainfall with embedded thunderstorms on Friday for eastern North Carolina. Much of the central U.S. and Gulf Coast states continue to see above average high temperatures by around 5-15 degrees this week. Forecast highs through Thursday will range from the 40s and 50s in the Great Lakes/Midwest; 50s in the northern Plains; 50s and 60s in the central Plains, Middle Mississippi Valley, and Ohio Valley; the 70s for Texas and the Lower Mississippi Valley, and the 80s along the Gulf Coast and into Florida. Frontal passages and generally unsettled weather along the East Coast and in the West will keep temperatures cooler and more seasonable in these areas. Forecast highs range from the 30s and 40s in New England, the 40s and 50s in the Mid-Atlantic, and the 50s and 60s from the Carolinas south into Georgia. In the West, highs Wednesday are in the 40s and 50s for the Pacific Northwest and Interior West, the 60s in California, and the 70s in the Desert Southwest. Temperatures will moderate for eastern interior areas on Thursday as upper-level ridging builds northward, with highs climbing into the 50s and 60s for the Rockies and Four Corners Region, and the 80s for the Desert Southwest. By Friday, colder air will be ushered into the West Coast while rain will keep it cool along the East Coast. Kong/Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php thunderstorms and isolated flash flooding concerns to the Tennessee and Mississippi as well as the lower Ohio Valleys Wednesday