A tropical threat on the Gulf Coast has a 40% chance for development into a tropical depression in the next 48 hours, according to the National Hurricane Center.

The system, which could currently be considered a “tropical rainstorm” or “tropical disturbance,” is likely to bring heavy rain to the central Gulf Coast for days — especially to the state of Louisiana.

The disturbance is expected to move along the coast, but the closer it stays to shore, the less chance it will have to grow into a tropical depression or storm since these weather patterns need time over water to develop, though a change to a more southerly track would give it a chance to gain steam.

A flood watch will go into effect at 1 p.m. this afternoon for portions of Louisiana and Mississippi and is expected to last at least through Friday night, with the eastern part of the watch in effect until at least Saturday evening.

This tropical disturbance is expected to produce long duration heavy rainfall and, if it develops into a tropical storm, it would be designated by the name Dexter.

Rainfall totals are generally expected to be between 2 and 6 inches, but the National Weather Service is highlighting some localized areas expected to receive as many as 15 inches in the region.

Elsewhere, heavy showers and thunderstorms are expected today for Ohio, West Virginia all of Pennsylvania, Virginia, Maryland and New Jersey with rainfall rates of potentially more than 2 inches per hour on Wednesday and Thursday.

Storms are expected to begin around 2 p.m. in Ohio and then move east in a very scattered fashion through the afternoon, evening and overnight.

A flood watch is already in place for central and northern New Jersey where 1 to 2 inches of rain could fall in a 1-to-3-hour period, likely in the evening or overnight hours for this location.

A severe risk for damaging wind and tornadoes, along with flash flooding, is in place for portions of Illinois, Wisconsin and Michigan on Wednesday, including Chicago, Milwaukee, Green Bay and Peoria.

A flood watch is already in place for Green Bay where they are expecting 2 to 3 inches of rain over a short time span, with locally higher amounts possible, and storms may reach Chicago, Milwaukee and Green Bay around 4 p.m. local time.

Heavy thunderstorms are also possible late tonight from Kansas to northern Missouri, with rainfall rates of 1 to 2 inches per hour possible.

Meanwhile, 70 million Americans are under heat advisories coast-to-coast, with dangerously hot conditions expected today for people in the Northwest, South and Northeast.

For the Northwest, a heat advisory is in place from northern California to northern Washington as Portland, Oregon, could reach near 100 degrees and Seattle, Washington, could hit the low to mid 90s — temperatures that are 10 to 15 degrees above average.

A heat advisory is in effect for parts of the South from Louisiana to Illinois, with a heat index up to 105 to 109 possible, including New Orleans, Memphis, Little Rock and Shreveport — temperatures that are 5 to 10 degrees above average.

The United States is now heading into the hottest part of the year, climatologically, and this weekend looks seasonally hot across the nation, with above average heat possible next week, especially for the Midwest, South and East, meaning temperatures in the upper 90s and lower 100s, with humidity making things worst for these regions.