Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 320 AM EST Tue Nov 29 2022 Valid 12Z Tue Nov 29 2022 - 12Z Thu Dec 01 2022 ...Heavy snow for parts of the Cascades/Central Rockies and the Upper Great Lakes/Upper Mississippi Valley... ...There is a Moderate Risk of excessive rainfall for parts of the Central Gulf Coast, Lower Mississippi Valley, and Southeast... ...There is a Moderate Risk of severe thunderstorms for parts of the Lower Mississippi and Tennessee Valleys... On Tuesday morning, a deepening wave of low pressure over the Central Plains moves northeastward into western Ontario, Canada, overnight Tuesday. On Tuesday, the low pressure will aid in streaming moisture northward from the Western Gulf of Mexico over the Lower Mississippi Valley into the Upper Great Lakes. Showers and severe thunderstorms will develop over the Lower Mississippi Valley into the Western Ohio Valley. Therefore, the SPC has issued a Moderate Risk of severe thunderstorms over parts of the Lower Mississippi and Tennessee Valleys through Wednesday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. There is a greater probability of EF2-EF5 tornadoes and hail two inches or greater over parts of the region. Moreover, there will be heavy rain associated with these thunderstorms. Therefore, the WPC has issued a Moderate Risk of excessive rainfall over parts of the Central Gulf Coast, Lower Mississippi Valley, and Southeast through Wednesday morning. The associated heavy rain will create numerous areas of flash flooding. Furthermore, many streams may flood, potentially affecting larger rivers. On Wednesday, the front associated with the wave of low pressure will move eastward from the Lower Great Lakes to the Central Gulf Coast, moving off the East Coast overnight Wednesday. As a result, showers and severe thunderstorms will move eastward to the Eastern Gulf Coast/Southeast as the severe thunderstorm threat lessens to a Moderate Risk. Likewise, the threat of excessive rainfall also moves eastward and decreases to Marginal Risk over Eastern Gulf Coast/Southeast/Southern Appalachians on Wednesday. Meanwhile, on Tuesday, weak onshore flow and upper-level energy will aid in producing coastal rain and higher-elevation snow over the Pacific Northwest and Northern/Central California into the Northern Intermountain Region, Northern/Central Rockies, and Great Basin. The snow has prompted Winter Storm Watch for the Cascades, Northern Intermountain Region, and Northern/Central California. However, by late Tuesday morning, the snow levels will lower to near the coast over the Olympic Peninsula, with heavy snow over the Olympic ranges. The snow will result in reduced visibility and hazardous driving conditions. Furthermore, the snow levels will lower over Northern California overnight Wednesday into Thursday. Moreover, on Tuesday, a front over the Upper Great Lakes to the Central Plains moves eastward to the Upper Great Lakes by Wednesday. As a result, snow will develop over parts of the Northern/Central Plains and move into the Upper Mississippi Valley/ Upper Great Lakes by Tuesday afternoon. Heavy snow will develop over the parts of the Mississippi Valley/ Upper Great Lakes, which has prompted Winter Storm Warnings and Winter Weather Advisories over the region. By Tuesday evening, rain develops along with the snow over the Upper Great Lakes. Overnight Tuesday, rain will change over to snow over the Western Ohio Valley as rain moves into the Northeast and Mid-Atlantic. Overnight Wednesday, the rain moves off the Northeast/Mid-Atlantic Coast as snow moves into Northern New England. Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php