Weather warnings: 66M under heat advisories as Florida braces for deluge

Sept. 5 (UPI) -- Much of the western United States will face potentially record-high temperatures late this week and into the weekend while northern Florida and the Gulf Coast will receive more waves of heavy rain, forecasters said Thursday.

As the first week in September drew to a close, the biggest weather concern was clearly in sweeping expanses of the western United States, including the Pacific Northwest, the Great Basin region of Nevada and Utah, the Southwest, southern California, Rocky Mountains and into the Northern High Plains.

There, high temperatures are expected to be 10 to 20 degrees above average, setting up the likelihood of continued record high temps on Friday and Saturday over portions of the Pacific Northwest and into the northern Great Basin, as well as in parts of southern California on Saturday, according to the National Weather Service.

Excessive heat warning and heat advisories already were in effect for much of Washington state, Oregon, California, far southern Nevada and into southwest Arizona on Thursday.

High temperatures in Spokane, Wash., will range between 92 and 102 degrees Fahrenheit over the next three days, which could produce a new record for early September in the city.

It will also be quite hot in the South and along the Gulf Coast as parts of that region hunker down for more heavy rain unleashed by a lingering, slow-moving tropical depression.

Heat advisories were in effect Thursday for parts of the South and southwestern Florida, which when combined with high humidity will likely produce dangerous heat indices up to 112 degrees.

In total, about 66 million people under were under heat warnings and advisories across the West, South and southwestern Florida, the NWS said.

Those sweltering the early September heat along the Gulf Coast will also have to deal with more pelting rain starting late this week and throughout the weekend. Forecasters said there is potential for 5 to 10 inches of rain falling in an area stretching from the Upper Texas coast, through southern Louisiana and into far southern Mississippi during the period.

In Florida, emergency officials warned that heavy rainfall is expected to affect the northern part of the state from Thursday through Saturday, leading to an increased risk of flooding.

Meanwhile, hurricane watchers said Thursday they were keeping an eye on five tropical disturbances in the Atlantic Ocean even as activity has been slow to develop in September, which is historically the peak of the Atlantic hurricane season.

The disturbances at this point remain tropical waves, which under the right conditions can lead to the formation of a tropical cyclone.

And in contrast to the heat of the West and South, cooler, fall-like temps are forecast for a wide swathe of the country stretching from the Plains eastward into the East for the remainder of this week and into the weekend.

In the wake of a cold front that moved through early Thursday, these areas will experience below-average temperatures and dry conditions producing "early fall-like conditions," according to the NWS.

"We'll get a taste of Fall Friday & Saturday before the return of Summer-like temps," the NWS office in Minneapolis said in a social media post .