Virginia Gov. Ralph Northam (D) declared a state of emergency Saturday in anticipation of the potential impact of Tropical Storm Florence, which the National Weather Service expected to become a “dangerous major hurricane.”.

The governor’s office said the order was intended to mobilize resources in preparation for the storm. It also aimed to help the state mitigate possible damage and facilitate the process by which Virginia provides aid to other vulnerable states.

In an 11 p.m. advisory, the weather service said Florence was expected to strengthen Saturday night from a tropical storm to a full-fledged hurricane .

“Florence is expected to become a hurricane at any time soon and rapid intensification is likely to begin on Sunday.’ the hurricane center said . It said the storm was “ forecast to become a major hurricane by Monday.“

It was about 790 miles southeast of Bermuda , with maximum sustained winds of 70 mph.

“The risk of direct impacts continues to increase,” the center said earlier.

However, the hurricane center said in its 11 p.m. . advisory, “given the uncertainty” in forecasts of the storm’s track and uncertainty over the time period, it was too soon to say when, where and how powerfully the storm would strike.

It said the East Coast, particularly from north Florida to North Carolina, should keep a close watch on Florence’s movements and developments.

Swells from the storm were beginning to reach parts of the U.S. East Coast and were likely to result in “life-threatening” surf and rip currents, the hurricane center said.

In a chart, the hurricane center indicated at least a 10 per cent probability of tropical storm force winds over the District, and much of Virginia and Maryland. Tropical storm winds were at least 39 mph, the chart said.

In his statement, Northam noted the uncertainties involved. But he also said forecasts “increasingly expect” strengthening into a major hurricane that could “seriously affect the East Coast and Virginians.”

“Accordingly,” he added, “I am declaring a state of emergency so that we can begin to prepare state assets, and I encourage Virginians to monitor forecasts and make their own preparations now.”

A state of emergency allows the commonwealth to mobilize resources, including the Virginia National Guard, and put people and equipment in position to help with storm response and recovery efforts.

In light of the uncertainties connected to the storm, Virginia’s emergency management officials encouraged preparation by all state residents, Northam said.

Effects could be widely felt, he said, from “high winds and storm surge in coastal Virginia to significant flooding both along the coast and in rivers and streams” in western areas.

Calling flooding the most deadly and dangerous aspect of hurricanes, he urged the public to recognize that flash floods can occur at any time.

In addition, the governor asked residents to assemble emergency kits to be brought along in case swift evacuations were called for. He also cited the importance of coastal residents knowing their evacuation zones before any storm impact was felt.

Warnings about Florence came against a backdrop of wet and stormy weather in the Washington area.

While Florence remained far out in the Atlantic, dark clouds and heavy rain Friday and Saturday seemed an appropriate way to herald its possible arrival.

On Friday, Washington was deluged with 2.89 inches of rain, as measured at Reagan National Airport.

Thunder pealed and boomed, lightning flashed, and rain seemed inescapable. In three separate Friday hours, more than half an inch fell in the city.

The .20 inches measured as of 5 p.m. Saturday brought the month’s total to 3.9 inches, well above the .88 inches that is normal here at this point in September. More was expected late Saturday and early Sunday.