Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 110 PM EST Mon Feb 03 2025 Valid 00Z Tue Feb 04 2025 - 00Z Thu Feb 06 2025 ...Unsettled weather to persist across the Northwest U.S. into early next week with much colder temperatures and heavy snowfall across the Cascades, northern Great Basin, northern Rockies and northern High Plains... ...An atmospheric river will continue to stream across northern and central California with heavy rains and areas of flooding possible through Tuesday... ...Storm system crossing the Great Lakes region to bring accumulating snowfall to parts of the Northeast... ...Record high temperatures are expected across portions of the Southwest out through the Southern Plains through the middle of the week... A deep layer cyclone will continue to impact the Pacific Northwest and the northern Rockies through Tuesday with unsettled weather expected. Moist onshore flow into the higher terrain coupled with cold air filtering south from British Columbia will drive heavy accumulating snowfall across the Cascades and especially interior mountain ranges. The atmospheric river that is bringing heavy rainfall to areas of northern California is being steered up the larger scale pattern northeastward up across areas of southern and eastern Oregon, and into the southwest facing slopes of the northern Rockies which should lead to heavy snowfall accumulations and including even some lower elevation locations. For the Cascades, generally an additional 6 to 12 inches of snow is expected through early Wednesday, with amounts over a foot expected from the terrain of northern California into the northern Rockies. The deep layer fetch of Pacific moisture overrunning Arctic air combined with upslope flow east of the Continental Divide will allow for heavy snowfall in the northern High Plains. The atmospheric river bringing the flooding threat for northern and central California should persist through Tuesday as a stationary front lingers. A couple waves of low pressure rippling along the front coupled with upslope flow into the higher terrain should yield an additional 5 to 10 inches of rain. A Slight Risk of excessive rainfall remains northern and central California through Tuesday. A frontal system traversing the Great Lakes region will bring a swath of accumulating snow across portions of northern New York and northern New England Monday evening into Tuesday. Several inches of new snow accumulation is expected. This system will pull away through southeast Canada tonight with a trailing cold front then crossing the region and bringing a renewed surge of cold air. Warm air aloft overrunning a returning warm front over this cold airmass is expected to lead to widespread, impactful freezing rain event from the Midwest across the Lower Peninsula of Michigan into the Mid-Atlantic States Wednesday and into southern New England Thursday. In addition to the dangerous travel conditions this may cause, the highest ice storm potential (with 1/4 inch or greater ice accretion) is expected from western Maryland northward into the Laurel Highlands of Pennsylvania, where scattered power outages and tree damage is most likely. An arctic high pressure system settling south from Canada across much of the northern tier of the Lower 48 will cause temperatures to fall well below average. Across the northern High Plains, temperatures will be as much as 15 to 30 degrees below normal, with daytime highs locally staying below zero. South of the front, very warm temperatures are expected across much of the southern tier of the country. Temperatures should reach well into the 80s across the interior of the Southwest and the southern Plains, with record high temperatures expected. Roth Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php