Weather Across America

(NATIONAL) Heat wave focus shifts from the Mid-Atlantic to portions of the Southeast and Southern Plains, a Slight Risk of Severe Thunderstorms over portions of the Northern High Plains, severe storms for portions of the Upper Midwest and monsoon-like conditions persist for the Southwest.

A broad and well entrenched upper ridge centered over the Southern High Plains and Southwest will eject shortwave energy across the northern tier states through the early work week. 

A low pressure system will slide across the Northeast and potentially into the Canadian maritimes Sunday night. Scattered to isolated showers and thunderstorms will focus around an attendant cold front propagating through much of the Northeast and northern Mid-Atlantic coast. 

Remnant moisture from Tropical Cyclone Alberto will bring early monsoon-like conditions to the Southwest and Four Corners region over the next few days. Scattered to isolated showers and thunderstorms will occur with some instances of flash flooding possible, particularly over slot canyons and favorable terrain. 

There's a Slight Risk (at least 15%) of Excessive Rainfall leading to Flash Flooding over portions of southeastern Arizona on Monday with Marginal Risks (at least 5%) persisting through mid-week.

Elsewhere, shortwave energy propagating across southern-central Canada and the northern tier CONUS will influence more thunderstorm activity over the Upper Midwest/Great Lakes beginning Monday afternoon. 

There's a Slight Risk of Severe Thunderstorms (level 2/5) over parts of the Upper Midwest late Monday afternoon. Severe and destructive wind gusts are possible for parts of Minnesota into Wisconsin. A cold front at the surface will act as a focus for showers and thunderstorms across portions of the Middle Mississippi Valley and Midwest on Tuesday. 

There's a Slight Risk of Severe Thunderstorms for parts of Iowa/northern Missouri into northern Illinois, southern Wisconsin, southwest Lower Michigan, northern Indiana and northwestern Ohio. 

There's also potential for an MCS to move across parts of Wisconsin and Michigan into northern Illinois and Indiana Tuesday morning, the outflows of which should set the stage for afternoon evening convection to take place after diurnal heating occurs. 

And there’s a targeted Slight Risk of Excessive Rainfall over parts of eastern Iowa, southern Wisconsin and northern Illinois, where storms yielding high rain rates could cause flash flooding.

A mid-level trough moving off into the Atlantic will promote widespread record warm low temperatures across the Northeast/Mid-Atlantic Coast Sunday night. Lows in the 70s will be of particular concern to those without adequate cooling or hydration. Heat Advisories are in effect for much of the aforementioned areas. 

Upper ridging centered over the Southern High Plains will produce warmer than average temperatures across the West and Central U.S. this week. Troughing over the northern tier will keep temperatures at or below average for parts of the Upper Midwest/Great Lakes.