Weather across America

(NATIONAL) Late season snow for the Upper Midwest,  heavy rain and severe thunderstorms for portions of the Lower Mississippi Valley/Central Gulf Coast and Southeast, and a Critical Risk of fire weather over parts of the Southern Rockies and the Central High Plains.

Low pressure over the Northern Plains will slowly move eastward to the Lower Great Lakes and merge with a second low moving northeastward from the Southeast by Tuesday morning. The system will produce rain and snow and rain over parts of the Northern Plains and Upper/Middle Mississippi Valley by Sunday evening. Overnight Sunday, snow develops over parts of the Upper Great Lakes/Ohio Valley. On Monday, the snow moves into the Lower Great Lakes and parts of the Ohio Valley and Northern Appalachians. Overnight Monday, the snow moves into Northern New England and Central Appalachians, with coastal rain over Southern New England. For Tuesday, the snow and rain continue over parts of the Northeast, northern Mid-Atlantic, and Eastern Ohio Valley. 

Meanwhile, an upper-level low moves out of the Northeast into Southeastern Canada overnight Sunday. The energy will aid in producing light snow over parts of Northern New England through late Sunday night. 

Additionally, a front lingers over the Gulf Coast States into the Southern Plains through Monday morning. As a result, showers and thunderstorms will develop along the boundary over parts of the Southeast to the Lower Mississippi Valley. The front will also aid in destabilizing the atmosphere over the Southern Plains to the Southeast. Therefore, the Storm Prediction Center has issued an Enhanced Risk of severe thunderstorms over the Lower Mississippi Valley/Central Gulf Coast and a Slight Risk over parts of southeast Texas through Monday morning.

The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. 

There will also be a Marginal Risk of excessive rainfall with these thunderstorms over the Lower Mississippi Valley/Central Gulf Coast. In addition, an excessive rainfall threat develops over the Southeast on Sunday during the showers and thunderstorms over the region. Therefore, the Weather Prediction Center has issued a Slight Risk of excessive rainfall over the Southeast through Monday morning. 

The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams being the most vulnerable. The excessive rainfall threat ends on Monday, and the severe thunderstorms threat is reduced to a Marginal Risk of severe thunderstorms over parts of the Southeast. 

Rain with embedded thunderstorms will continue over parts of the Mid-Atlantic/Southeast on Monday, with the rain dwindling to New England Coast by Tuesday morning.  

Furthermore, overnight Sunday, a front over the Pacific will begin to move onshore over the Pacific Northwest and move inland to the Rockies by Tuesday. The system will produce coastal rain and higher elevation snow over the Pacific Northwest and Northern California early Monday morning into Tuesday evening. The light snow expands into the Northern Intermountain Region by Tuesday morning and parts of the Northern Rockies by Tuesday evening.  

Moreover, the SPC has issued a Critical Risk of fire weather over the Southern Rockies into the Central High Plains through Monday morning. The fire weather hazard is due to gusty winds, dry fuels, and low humidity. However, the fire weather risk lowers on Monday to an Elevated Risk over parts of the Southwest to the Southern Rockies. A second Elevated Risk area is over far eastern Nebraska and western Iowa. 

Additionally, upper-level energy over the Southern Rockies/Southern Plains and moist flow off the Western Gulf of Mexico will produce showers and thunderstorms over parts of Southern Plains on Tuesday into Tuesday evening.