Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EST Thu Dec 12 2024 Valid 12Z Thu Dec 12 2024 - 12Z Sat Dec 14 2024 ...Great Lakes heavy lake-effect snow expected to continue into Friday especially along the Snow Belt of the lower Great Lakes... ...A couple rounds of heavy coastal rain and heavy mountain snow expected to impact northern California into Sierra Nevada heading into the weekend... ...Sub-zero temperatures expected over parts of the northern Plains and upper Mississippi Valley for the next couple of mornings... As a deep low pressure system races further northward into eastern Canada and a potent cold front exits New England this morning, an arctic high pressure system will take over the northern Plains and expand across the entire eastern U.S. through the next couple of days. Maine will be the last to clear out from the heavy rain early this morning followed by much colder temperatures under blustery westerly winds. The resurgence of arctic air is triggering a new round of heavy lake-effect snow across the Great Lakes through today and tonight before gradually tapering off on Friday. The Snow Belt of the lower Great Lakes can expect a foot or more of new snow, with locations downwind from Lake Ontario possibly getting more than 2 feet since these locations will be the last to clear out from the snow late on Friday. Along the West Coast, moisture ahead of the next Pacific cyclone is poised to overspread much of the Pacific Northwest and a good portion of California today. The heaviest precipitation is expected to reach northern California in form of rain near the coast and lower elevations. A quick round of moderate to heavy snow will then reach the high elevations farther inland and then along the Sierra Nevada for much of today. It appears that this latest around of precipitation will taper off temporarily tonight before the next round of precipitation associated with the next Pacific cyclone arrives on Friday. Northern California into southwestern Oregon can expect heavy precipitation Friday night with a marginal risk of excessive rainfall continuing into Saturday morning by the end of the short-range forecast period. Lesser amounts of precipitation are expected for the Pacific Northwest. The arctic high pressure system that is forecast to bring sub-zero temperatures for the next couple of mornings is forecast to strengthen and slide east into New England by Saturday morning. This will allow southerly flow to increase across the southern Plains along with moisture returning from the Gulf of Mexico by Friday night. Meanwhile, residual energy associated with the first Pacific system is forecast to exit the southern Rockies and induce the formation of a low pressure system over the central Plains by Friday night. Some thunderstorms along with heavy rain could quickly develop and move across the central Plains early on Saturday ahead of the new low pressure system. Colder air could support areas of mixed rain and snow farther north across the north-central Plains into the upper Midwest in advance of the low pressure center. In the short-term though, dry, breezy and relatively mild conditions will support elevated fire danger across the southern High Plains for today. Kong Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php