Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EST Wed Dec 11 2024 Valid 12Z Wed Dec 11 2024 - 12Z Fri Dec 13 2024 ...Widespread heavy rain and severe thunderstorm treats spreading up the East Coast today and through New England into tonight... ...A surge of cold air into the eastern U.S. today will be followed by a reinforcing surge of arctic air into the northern U.S. through the next couple of days... ...Another round of significant lake effect snow expected through the next couple of days downwind of the Lakes... The stage is set for a rapidly intensifying low pressure system to track up the East Coast today. A potent cold front trailing southwest from the center of this elongated low pressure system will be the focus for heavy rain, blustery winds, and strong to severe thunderstorms. Ahead of the front, warm and moist air streaming in from the nearby Atlantic and Gulf of Mexico will interact more vigorously with a jet stream aloft to develop and expand the coverage of showers and thunderstorms, first across the Southeast and the Carolinas this morning, followed by the Mid-Atlantic states during the day, and into New England this evening. The highly dynamic nature of this front will likely trigger formation of strong to severe thunderstorms. This is especially the case across eastern North Carolina this afternoon, and into southern New England this evening, where the Storm Prediction Center has issued a Slight Risk (level 2 of 5) for severe thunderstorms capable of producing damaging wind gusts. Elsewhere along the Eastern Seaboard, the main concern will be a period of heavy rain with embedded strong thunderstorms and intense downpours. Despite much of the region currently experiencing moderate to extreme drought conditions, the rain, while mostly beneficial, could lead to some localized instances of flash flooding. The more urbanized locations and poor drainage areas would have the greater risk of flooding issues. Behind the potent cold front sharply colder air will surge into the East Coast from the north and northwest. A period of accumulating wet snow can be expected to spread up the western slope of the entire spine of the Appalachians from south to north today through tonight. Meanwhile, a reinforcing shot of arctic air is plunging into the northern Plains and will overspread much of the northern tier states through the next couple of days. High temperatures the next couple of days will be roughly 10 to as much as 30 degrees below normal. Attention then turns to yet another round of significant lake effect snow downwind of the Great Lakes through the next couple of days. The aforementioned surge of arctic air will stream across the still relatively warm Great Lakes and ignite intense bands of lake effect snow, initially downwind of Lakes Superior and Michigan on today and then downwind of Lakes Erie and Ontario tonight into early Thursday. By the time the snow starts to taper off on Friday, snowfall totals of 1 to 2 feet are likely in the favored Snow Belt across portions of northwest and western New York State, far northwest Pennsylvania, far northeastern Ohio, the Upper Peninsula of Michigan and the western portions of the Lower Peninsula of Michigan. Along the West Coast, moisture ahead of the next cyclone from the Pacific is poised to overspread much of the region through the next couple of days. Northern California will see heavy coastal rain by this evening, followed by heavy mountain snow farther inland and down the Sierra Nevada where a foot or more of new snow is forecast through Thursday. It appears that this round of precipitation will mostly taper off Thursday night prior to the arrival of the next Pacific system. Kong/Miller Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php