Flash flooding risk in Mississippi, Tennessee, and Ohio valleys; California hit by mudslides

According to the National Weather Service (NWS), a significant flash flooding event is developing across the lower to mid-Mississippi, Tennessee, and Ohio Valleys. Severe thunderstorms in the Deep South will further exacerbate conditions.

Repeated rounds of storms will bring rainfall rates of 1-2 inches per hour, with total accumulations between 3-6 inches, and isolated areas potentially receiving up to 8 inches. Northwestern Tennessee and western Kentucky are at the highest risk, with a High Risk (level 4/4) of Excessive Rainfall issued by the NWS. Moderate and slight risks extend eastward into the Appalachians.

The Storm Prediction Center has also issued an Enhanced Risk (level 3/5) for severe weather, including the possibility of strong tornadoes. As a potent cold front moves across the South, the risk of damaging winds and tornadoes will persist into Sunday.

Winter storm to impact the Upper Midwest and Northeast

The NWS reports that a developing winter storm will bring widespread moderate to heavy snowfall, affecting the upper Midwest, Great Lakes, and northern New England.

Winter Weather Advisories have been issued for snow totals in the range of 3-6 inches. Upstate New York and northern New England will likely experience heavier snow accumulations as the system strengthens. Increasingly strong winds may lead to blowing snow and hazardous travel conditions. Higher elevations of the Appalachians will also receive moderate snowfall. By Monday, the storm is expected to move east of New England, though lake-effect snow will persist downwind of the Great Lakes due to cold northwesterly winds.

Arctic air surge to bring bitter cold to the Plains

A surge of arctic air from Canada will spread southward this weekend into early next week, bringing frigid temperatures to the northern and central Plains.

High temperatures will drop into the single digits and teens, with some locations struggling to rise above zero by Sunday. The coldest temperatures are expected near the Canadian border, where lows could reach -30 degrees Fahrenheit. Strong winds will result in wind chills well below zero. This arctic blast will extend into the Mississippi Valley and southern Plains, bringing highs only in the 30s and 40s.

Pacific Northwest to experience heavy rain and snow

The NWS forecasts a Pacific storm system to bring a new round of precipitation to the Pacific Northwest starting late Saturday.

Coastal areas will see moderate rainfall, while interior valleys will receive a mix of rain and snow. Higher elevations, especially in the Cascades and northern Rockies, will experience moderate to heavy snowfall. By Sunday night, this system will begin interacting with an arctic front, expanding snowfall across the northern Rockies and into the northern Plains.

Temperature outlook

Ahead of the storm system, temperatures will be above average in the central and eastern U.S. The NWS expects highs in the 50s to 70s across the Ohio Valley, lower Mississippi Valley, and Gulf Coast. By Sunday, temperatures will rise into the 50s and 60s in the Mid-Atlantic and Carolinas, with 60s and 70s in the Southeast. However, the arrival of arctic air will rapidly drop temperatures behind the cold front, leading to a sharp contrast between warm and bitterly cold conditions.