Weather across America

(NATIONAL) Severe weather and heavy rain chances shift before progressing, dangerous and potentially record-breaking heat continues across parts of Texas and Florida, and active weather returns to the southern Plains.

An organizing storm system over the central U.S. is responsible for numerous thunderstorms stretching from Kansas/Missouri to the Edwards Plateau of Texas. Boundaries aiding this convection include a dryline extending southward through the southern Plains and a slowly lifting warm front stretching from the central Plains through the Ohio Valley. Storms are expected to grow upscale and merge into a larger complex of thunderstorms by morning while swinging through parts of Missouri, Illinois, western Kentucky, and neighboring states. 

Damaging wind gusts, large hail, and tornadoes are possible. Additionally, heavy rain may lead to scattered instances of flash flooding with this initial burst of thunderstorms. Another round of showers and thunderstorms are expected to develop along a cold front and impact similar regions, with the severe threat shifting further east across the Ohio Valley Sunday night

More chances for all modes of severe weather are possible, with repeating storms potentially increasing the flash flooding threat throughout parts of Kentucky and Tennessee. Areas of heavy rain may also lead to flash flooding concerns near the low pressure center as it progresses toward southern Wisconsin Sunday night. As the center of the storm system enters the Great Lakes on Monday and the attached cold front extends from the Ohio Valley to the southern Plains, severe weather and heavy rain chances will focus along the eastern U.S. and Gulf Coast States. 

More specifically, the greatest chances for intense rainfall rates leading to flash flooding exists across eastern Pennsylvania and neighboring section of southeast New York and northwest New Jersey, where a Slight Risk (level 2/4) of Excessive Rainfall is in effect on Memorial Day. Severe thunderstorms are most likely across the Mid-Atlantic as well as an area stretching from the Lower Mississippi Valley to the Southeast. Damaging wind gusts and hail are the primary potential hazards. 

Residents and visitors planning to enjoy outdoor holiday barbecues and parties should remain weather aware and have multiple ways to receive warnings. Oppressive and potentially dangerous heat is set to continue for at least the next few days throughout parts of southern Texas, the lower Mississippi Valley, and southern Florida. Highs are expected to reach well into the 90s for the southern Plains and western Gulf Coast, with triple digits across southern portions of Texas.

Elevated humidity levels will make it feel even hotter, with heat indices approaching 115 degrees. Daily record highs are also possible in this region and extending to southern Florida as well through Tuesday. Residents and visitors are urged to follow proper heat safety by staying hydrated, taking breaks inside buildings with air conditioning, as well as checking on the vulnerable population. Above average and summer-like temperatures will also extend towards the eastern U.S. today as well before slightly cooler weather arrives behind a cold front on Tuesday. 

Conversely, a warm up is on the way throughout the West as upper ridging builds and spreads highs into the 70s and 80s for the northern Great Basin and northern High Plains. The next round of active weather is set to impact the southern Plains on Tuesday as a lingering frontal boundary and favorable upper jet dynamics spark developing thunderstorms from western Oklahoma/Kansas to Texas and the lower Mississippi Valley.

Scattered instances of flash flooding are possible, which is highlighted by a Slight Risk of Excessive Rainfall throughout central and north-central Texas, as well as southern Oklahoma. Some storms in the southern High Plains may also become strong enough to produce damaging wind gusts and large hail.