A pesky low-pressure system will keep isolated showers a threat today, but after the departure, a tropical air mass will return with a heat index rising towards 100 for the I-95 corridor.

An area of low pressure over the coastal waters will continue to drift away from the region this morning with scattered to broken cloud cover and a few isolated showers through this afternoon.  Winds will back from the northeast to the south at 5 to 10 mph.  Temperatures will rise into the upper 70s to mid-80s along the coast and mid to upper 80s away from the coast for highs.

High pressure will pass over the region tonight with scattered clouds and some locally dense fog towards the morning hours.  Winds will be from the south at 5 mph.  Temperatures will fall into the upper 60s to lower 70s for lows.

A tropical air mass will be in place tomorrow through Thursday with locally dense fog in the morning and isolated to widely scattered showers and thunderstorms in the afternoon.  The thunderstorms will be capable of intense downpours, frequent lightning, hail, and wind gusts over 40 mph.  Winds will be from the south at 5 to 10 mph.  Temperatures tomorrow will rise into the upper 70s to mid-80s along the coast and upper 80s to lower 90s away from the coast for highs.  Temperatures on Wednesday and Thursday will range from the lower to mid-70s for most of the region and mid to upper 70s in urban areas for lows and lower to mid-80s along the coast, upper 80s to lower 90s over the interior, and lower to mid-90s in the Delaware River Valley for highs.  A heat index over 95 degrees will be a threat in the afternoon hours.

A cold front will slowly sink through the region Friday through Sunday with waves of showers and thunderstorms.  A few thunderstorms will reach severe levels with tropical downpours, frequent lightning, hail, wind gusts over 60 mph, and isolated tornadoes.  Temperatures on Friday will range from the lower to mid-70s for most of the region and mid to upper 70s in urban areas for lows and mid-80s to lower 90s along the coast and higher elevations and lower to mid-90s in the Delaware River Valley for highs.  Temperatures on Saturday will range from the upper 60s to lower 70s over the interior and lower to mid-70s along the coast for lows and lower to mid-80s over the interior, mid to upper 80s along the coast, and upper 80s to lower 90s in the Delaware River Valley for highs.  Temperatures on Sunday will range from the lower to mid-60s for lows and upper 70s to lower 80s for highs.

High pressure will be in control on Monday with clear skies to scattered cloud cover.  Temperatures on Monday will range from the upper 60s to lower 70s for lows and upper 70s to lower 80s for highs.