A wave of low pressure over the Middle Mississippi Valley will move northeastward to off Northern New England Coast by Monday evening.
Article continues below
North of the low, snow will develop over parts of the Middle Mississippi Valley on Saturday evening.
Moderate to heavy snow will develop over parts of the Great Lakes overnight Saturday.
On Sunday, light to moderate snow will develop over parts of Northern New England and northern New York State.
Light snow will continue over the Great Lakes, especially downwind from the lakes, on Sunday, too.
In addition, moisture from the Gulf of Mexico will stream northward over the Western Gulf Coast/Lower Mississippi Valley into the Ohio Valley.
The moisture will produce rain and embedded thunderstorms over parts of the Western Gulf Coast and Lower Mississippi Valley from Saturday evening into early Sunday.
Rain will develop over parts of the Middle Mississippi Valley that will expand into the Ohio Valley overnight Saturday into Sunday.
The rain will then expand into parts of the Northeast and Mid-Atlantic on Sunday afternoon.
Along the rain/snow line, pockets of light rain/freezing rain will develop from the Middle Mississippi Valley into the Great Lakes from Saturday evening into Sunday evening.
On Monday, light snow will continue over parts of the Northeast into the Central Appalachians.
The snow will result in reduced visibility and the snow/ice will produce hazardous driving conditions.
Meanwhile, cold high pressure over the Northern Plains will move southward to the Central Plains by Monday.
The cold air will bring temperatures 15 to 35 degrees below average over parts of the Northern/Central Rockies and High Plains.
As the cold air moves southward, the pockets of rain/Freezing rain will extend from parts of the Southern Plains into the Ohio Valley from Sunday evening into Monday.
Furthermore, the moisture will aid in producing showers and thunderstorms with heavy rain over parts of the Western/Central Gulf Coast and part of the Southeast on Sunday.
Therefore, the WPC has issued a Slight Risk of excessive rainfall with these thunderstorms over the region from Sunday into Monday morning.
The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable.
Additionally, some of the thunderstorms will be strong to severe.
Therefore, the SPC has issued a Marginal Risk of severe thunderstorms over parts of the Western/Central Gulf Coast and part of the Southeast from Sunday into Monday morning.
The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes.
The threat of excessive rainfall and severe thunderstorms ends on Monday.
Moreover, an upper-level low will develop over Northern California on Sunday and move southward to Southern California and Northwestern Mexico by Monday evening.
A front associated with the energy will also move southward from the Pacific Northwest to the Southwest by Monday evening.
The system will produce coastal rain and higher-elevation snow over the Pacific Northwest on Saturday evening into Sunday morning.
The coastal rain and higher-elevation snow will move into California on Sunday.
Furthermore, snow will develop over parts of the Northern Intermountain Region and Northern Rockies from Saturday evening into Sunday morning.
On Sunday, the snow will move into the Great Basin and Central Rockies and parts of the Southwest on Monday.
The snow will result in reduced visibility and hazardous driving conditions. ■
A very strong low pressure system currently just offshore of San Francisco Bay will continue to bring high winds, heavy rain, and heavy mountain snow for California and adjacent areas of the Southwest through tonight and Wednesday as the latest in a series of atmospheric rivers impacts the West.