Enhanced risk for severe weather Sunday, flooding, isolated tornado possible

PHILADELPHIA (CBS) -- Scattered showers and storms continued into Sunday morning across the Delaware Valley, while South Jersey and the shore points were hit with torrential and flooding rain early in the day .

Much of the Philadelphia region is under a severe thunderstorm watch until 7 p.m. Sunday. Severe thunderstorm warnings are in effect in some places north and west of the city as well; those storms could bring strong winds and hail.

After a break, scattered thunderstorms will start again in the late afternoon and continue into the evening.

More potentially severe storms Sunday night

The expected heat has triggered a heat advisory from 11 a.m. until 7 p.m. for all areas adjacent to the I-95 corridor, including Philadelphia, Wilmington, Delaware and Trenton, New Jersey.

Because of the extreme heat and chance for more severe weather, we've declared Sunday a NEXT Weather Alert Day.

According to the National Weather Service office in Mount Holly, New Jersey, hail, lightning and wind gusts up to 75 mph are likely.

Sunday afternoon and evening, scattered showers and strong to severe storms will once again develop across the Delaware Valley ahead of a cold front. Our entire area is now under an enhanced risk of severe weather, or Level 3 on a five-point scale.

The main threats are damaging winds, heavy rain with possible flash flooding and an isolated tornado. The storms arrive in the Lehigh Valley between 2-5 p.m., Philadelphia between 4-7 p.m. and South Jersey between 6-10 p.m.

A flash flood warning will be in effect in Philadelphia, Delaware and Chester Counties until 8:15 p.m. on Sunday.

Cooler start to the week

Following Sunday's storms, cooler and more comfortable conditions arrive on Monday and Tuesday, where we'll see sunshine and highs in the low 80s.

On Wednesday, we warm up again to near 90 with partly sunny skies. Then for the Fourth of July it'll be muggy and hot with highs in the low 90s and a feels-like nearing 100.

Another Heat Advisory and NEXT Weather Alert may be needed for Thursday. Showers and storms are also possible for the holiday on Thursday, although these may be very widely scattered.

Keep it close to CBS Philadelphia today, as the entire NEXT Weather Team continues to monitor the severe weather threat across the Delaware Valley.

7-day forecast

Sunday: High of 91, NEXT Weather Alert Day

Monday: High of 82, low of 63, sunny and warm

Tuesday: High of 86, low of 63, sunny and warm

Wednesday: High of 86, low of 65, mostly sunny

Thursday: High of 93, low of 72, storm or two possible

Friday: High of 91, low of 74, few storms

Saturday: High of 91, low of 75, scattered storms