Weather across America

(NATIONAL) Severe thunderstorms and an isolated threat of flash flooding across parts of the Lower Mississippi Valley and Tennessee Valley, and locally heavy rainfall and a threat for flash flooding over the central High Plains.   

Unsettled weather with a threat for additional rounds of severe weather, heavy rain and possible flash flooding is expected Monday and Tuesday from the Red River Valley of the South through portions of the Mid-South and Gulf Coast states.

Triple digit and potentially record-breaking heat builds into much of Texas over the next few days.

A strengthening low pressure system progressing from the Ohio Valley to the Lower Great Lakes and Northeast by early this week combined with a trailing front that will settle down across the South and stretch back to the central High Plains will continue to focus unsettled weather with numerous clusters of thunderstorms and locally heavy rain. 

Several thunderstorms developing ahead of an associated cold front between the Lower Mississippi Valley to the Tennessee Valley through Sunday evening are expected to turn severe, potentially producing damaging winds, large hail, and a few tornadoes. The Storm Prediction Center has issued a broad Enhanced Risk (level 3/5) of severe thunderstorms for the Mid-South and Tennessee Valley. 

Additionally, locally heavy rain may accompany the relatively fast-moving storms and create at least an isolated threat for flash flooding concerns for these same areas and also up into portions of the Ohio Valley. Much of the rainfall that does occur over these areas should be beneficial given very dry antecedent conditions and ongoing localized drought concerns. As the aforementioned low pressure system pushes into the Lower Great Lakes and Northeast on Monday, a warm front will initially lift north across the region followed by a cold front, and the combination of these should foster numerous areas of showers and thunderstorms across the Mid-Atlantic through New York and much of New England. 

These areas have also been very dry this spring, and the rains are expected to be beneficial, however there may be some localized small stream and urban flash flooding concerns where the heaviest rains set up.  

Farther west, a front will remains draped up across the eastern slopes of the central Rockies and adjacent High Plains which coupled with upslope flow and moisture transport into this region should favor scattered to broken areas of showers and thunderstorms. Some of these storms may turn severe and create a flash flood threat this evening and again on Monday. 

The Storm Prediction Center does depict a Slight Risk (level 2/5) of severe thunderstorms capable of producing damaging winds and large hail through Sunday evening for areas of the Colorado Front Range southeastward into adjacent areas of the southern High Plains including the Oklahoma and Texas Panhandle. Heavy rainfall associated with the slower moving storms could create flash flooding over eastern Colorado where soils remain saturated due to a wet spring. The Weather Prediction Center has a Slight Risk (level 2/4) of excessive rainfall depicted for eastern Colorado through Sunday night, with the threat stretching from southeast Wyoming through eastern Colorado and into western Kansas on Monday.  

Heavy rainfall will also be a concern from the Red River Valley of the South to the Mid-South and adjacent downstream areas of the Gulf Coast states early this week as the previously mentioned frontal boundary gradually lifts back north and ushers in moist air from the Gulf of Mexico. 

Moisture and instability pooling along the front coupled with a wave of low pressure traversing it should help focus an axis of heavy showers and thunderstorms. Some additional concerns for some severe weather are expected along with a threat for isolated to scattered instances of flash flooding where the heavier rains set up.  

Elsewhere, an upper-level low churning over the Southwest and eventually the Intermountain West early this week will offer daily chances for scattered thunderstorms and locally heavy rain between the higher elevations of California and the northern Rockies. Farther south across southeast Arizona, central and southern New Mexico, and far west Texas, there will be increasing southwest winds which coupled with very low humidity will increase the threat for wildfires.  

Temperatures over the Lower 48 through Tuesday are expected to feature building heat across the Lone Star State. Highs into the upper 90s and triple digits for most of Texas are forecast over the next several days, with heat indices nearing 110 degrees across southern sections of the state. Daily high temperature records could be approached or broken by Tuesday. 

Residents are advised to take this early summer heat seriously and follow proper heat safety. Hot temperatures are also expected to be a concern across the Pacific Northwest on Monday and Tuesday with highs in the low 90s which will be as much as 20 degrees above average. Meanwhile, sustained below average temperatures are forecast beneath upper-level lows over the Southwest and Great Lakes, with cooler weather also expected over the central High Plains due to wet weather and cloudy conditions.