Weather across America

(NATIONAL) Heavy lake-effect snow for parts of Michigan and moderate snow over parts of the upper Midwest, a slight risk of excessive rainfall over parts of the middle/lower Mississippi Valley, below average temperatures over parts of the central/southern Plains, and wind and dry conditions across California will lead to an increased threat of wildfire activity.

Cold high pressure extending from the Pacific Northwest to the northern/central high plains will move southeastward to the southern plains on Monday. A reinforcing surge of cold air associated with a second high moves south out of Canada on Monday night and continues to the central/southern plains by Tuesday evening. The cold air associated with the high will allow temperatures to be 15 to 35 degrees below average over parts of the central/southern plains. 

In addition, the Santa Ana wind associated with the area of high pressure will produce a region of critical fire weather over parts of Southwestern California on Sunday evening into Monday. The fire weather area is due to maximum wind gusts up to 75 mph, which has prompted High Wind Warnings, low relative humidity, and dry fuels over the area. Moreover, the high will create upslope wind and light snow over the central/southern Rockies through Monday morning.

As the cold air settles over the southern plains, an area of light rain/freezing rain will develop over the area.  Further, a front extending from the Mid-Atlantic roughly southwestward to the southern plains will move off the northeast and western Gulf Coast Monday night into Tuesday while lingering over parts of the southeast by Tuesday. Furthermore, moisture from the Gulf of Mexico will overrun and pool along the boundary from the Ohio Valley to the southern plains, creating showers and thunderstorms with heavy rain over parts of the middle/lower Mississippi Valley. 

Therefore, the WPC has issued a slight risk of excessive rainfall over parts of the middle/lower Mississippi Valley through Monday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable. Meanwhile, rain will develop along the boundary from the Ohio Valley to the northeast through Monday evening. Additionally, with the cold air moving over the Great Lakes, heavy lake-effect snow will develop over the Keweenaw Peninsula of Michigan.  

Also, on Monday, a front over Central Canada will move southward into the northern plains/upper Mississippi Valley by Monday evening, then to the Lower Great Lakes/Tennessee Valley by Tuesday evening. The system creates light snow over parts of the northern plains/upper Mississippi Valley, moving into parts of the Great Lakes by Tuesday. Furthermore, the storm will produce lake-enhanced snow over the southern coast of Lake Superior into the higher elevations of the northern Lower Peninsula of Michigan overnight Monday into Tuesday. In addition, on Monday, a wave of low pressure moves across southern New England, creating moderate to heavy snow over northern Maine into Tuesday.