Weather across America

(NATIONAL) Severe thunderstorms and flash flooding possible from the northern Rockies to the northern Plains, early season monsoonal moisture to lead to widespread showers and thunderstorms, and well above average temperatures and excessive heat over the Heartland to advance east across the Mississippi Valley and Mid-South. 

A potent upper-level low churning above the Intermountain West will continue to produce unsettled weather over the next few days between the northern Rockies and northern Plains. Through Sunday night, a few developing thunderstorms will have the potential to produce damaging wind gusts, large hail, and isolated tornadoes across the northern High Plains. Heavy rain may accompany embedded thunderstorms throughout the northern Rockies and much of Montana as well. By Monday, the upper-level low is forecast to slowly eject into the northern High Plains and spark another round of potentially severe weather. 

Thunderstorms capable of containing strong winds and large hail will be possible throughout much of the northern Plains, which has prompted the Storm Prediction Center to issue a Slight Risk (level 2/5) of severe thunderstorms from north-central Nebraska to the upper Missouri Valley, including much of the Dakotas, eastern Montana, and northwest Minnesota. Meanwhile, periods of heavy rain will remain a concern across parts of central Montana as widespread moderate rainfall develops underneath and on the backside of the closed upper-level low.

Total rainfall amounts across parts of central and western Montana are expected to add up to around 1 to 3 inches. As a result, a Slight Risk (level 2/4) of excessive rainfall has been issued for parts of central Montana.

For the Southwest, much needed monsoon moisture has arrived and will continue to produce scattered showers and thunderstorms through at least midweek. Eastern Arizona, southern Colorado, and much of New Mexico could receive beneficial rainfall to alleviate ongoing severe to exceptional drought, with overall rainfall amounts ranging from 1 to 2 inches over the next several days. However, too much rain within a short period of time could lead to flash flooding. Flood Watches have been issued in parts of New Mexico and Colorado to highlight the threat. 

Areas near recent burn scars will be most at risk to rapid runoff and debris flow. A Slight Risk (level 2/4) of excessive rainfall has been issued for Tuesday across portions of north-central New Mexico.

Above average temperatures and dangerous heat is expected to continue making headlines across the central U.S. and Deep South during the last full week of June. The core of the much above normal temperatures is located over the northern Plains and Upper Midwest this afternoon, with high into the upper 90s and low 100s (around 20 to 30 degrees above average). These simmering temperatures will shift eastward on Monday to encompass more of the Midwest and Great Lakes, with a few daily high temperature records possible between Nebraska and northern Wisconsin. On Tuesday highs into the upper 90s will reach the Ohio/Tennessee Valley, while also extending into the Southeast. 

Meanwhile, steamy and sultry weather with isolated pop-up thunderstorm chances will remain across the Deep South and southern Plains each day on Monday and Tuesday. Highs just under the century mark will feel much hotter when factoring in humidity. Maximum heat indices may reach as high as 110 degrees along the central Gulf Coast in addition to warm overnight minimum temperatures only dropping into the upper 70s.

Elsewhere, well below average temperatures are expected underneath anomalous upper-level troughs over the West and Northeast. In fact, lows dipping into the 40s and 50s on Monday for the Mid-Atlantic and Northeast could be cold enough to break a few daily low temperature records. As a warm front pushes eastward through the Great Lakes on Monday and Tuesday, above average temperatures will return to areas along and west of the Appalachians with a few thunderstorms possible across the interior Northeast as well. 

Lastly, a weakening cold front over central Florida will create chances for strong thunderstorms and heavy rain this evening, with lessening chances on Monday.