The U.S. economy has sailed through some rapids this year, but now faces the risk of a confluence of risks that could create more turbulence for the economy.

The list of risks facing the economy this fall includes a widening strike by auto workers, a prolonged government shutdown, the resumption of student loan payments and rising oil prices.

Each of these challenges won't do much harm on its own. But the combination of these factors could be even more damaging, especially with high interest rates already cooling the U.S. economy.

"The combination of these four risks could disrupt economic activity," said Gregory Daco, chief economist at EY-Parthenon.

Many analysts expect U.S. economic growth to slow this fall, but not a recession. Daco forecasts that the US economy will slow sharply to an annualised 0.6 per cent in the fourth quarter from an estimated 3.5 per cent in the third quarter. Economists at Goldman Sachs expect growth to slow to 1.3% in the fourth quarter from 3.1% in the third quarter.

So far in 2023, while the Fed has raised interest rates to 22-year highs to fight inflation by cooling the economy, robust consumer spending and historically low unemployment have underpinned solid U.S. economic activity. At the same time, economic growth in Europe and China has slowed sharply.

One threat to the economy is a broader and longer strike by the United Auto Workers union against Detroit's three automakers. On September 15, nearly 13,000 workers at three factories went on strike. UAW President Shawn Fain said on Friday the strike would expand to 38 General Motors and Stellantis parts distribution centers in 20 states.

The limited strike is expected to have little initial impact, but a wider lockout could curb car production and push up prices. Workers at auto parts suppliers could also lose their jobs.

According to Goldman Sachs, each week of widespread strikes reduces annualized economic growth by 0.05 to 0.1 percentage points.

Due to plant shutdowns, the strike will also lead to a delay in the automotive industry fully recovering from the supply chain disruption caused by the outbreak. For much of last year, dealers had few cars on their hands as parts shortages crimped production levels. That has pushed up prices at a time when many families are looking to buy cars.

Domestic car production is getting closer to pre-pandemic levels. Over time, strikes could cut production and push up car prices again.

"I don't think we're going to see a recession because of this auto strike alone, but there are other headwinds dragging down the economy," said Gabe Ehrlich, an economist at the University of Michigan. "If these factors add up, the fourth quarter of this year could end 2023 with a stuttering performance," he said.

The next twist could be a partial shutdown of U.S. government agencies. Congress has until the end of September to agree on a government budget. For now, lawmakers are deeply divided.

If lawmakers fail to reach a deal, furloughs will be imposed on all but the most essential workers to keep the government running, putting as many as 800,000 Americans out of work. Those workers may reduce their spending during the shutdown, and government departments may temporarily cut back on purchases of goods and services.

In December 2018, a similar congressional standoff led to a five-week partial shutdown that kept funding for some agencies and left others without money. About 300,000 federal workers were furloughed. That shutdown reduced US economic output by 0.1 per cent in the fourth quarter of 2018 and 0.2 per cent in the first quarter of 2019, according to the Congressional Budget Office.

Since then, the government has reopened, federal workers have received back pay and much of the lost economic activity has been made up, according to the Congressional Budget Office.

Another factor is the resumption of federal student loan payments on October 1. Wells Fargo economist Tim Quinlan estimates that restarting student loan payments could take about $100 billion out of Americans' pockets over the next year.

This will be the first payment many borrowers have made since March 2020, when the Education Department suspended their payments to help ease the financial impact of the coronavirus pandemic. As the economy rebounds, the move allows people to spend their money elsewhere, helping to boost growth.

The tens of millions of student loan borrowers affected have monthly payments averaging between $200 and $300 each. While that's a relatively small share of the $18 trillion in annual U.S. consumer spending, it worries Walmart Inc. (WMT), Target and other big retailers.

Rising gasoline prices add to those pressures. Brent crude has been hovering above $90 a barrel for the past few days, compared with just over $70 this summer. According to the Labor Department, gasoline prices surged 10.6 percent in August from a month earlier, the biggest one-month increase since June 2022.

That led to a second straight month of slightly higher CPI after last year's downward trend. Gasoline prices remained mostly higher in September. The average price of a gallon of regular gasoline was $3.86 on Friday, according to OPIS, an energy data and analysis provider.

Rising energy costs have the same impact as paying off student loans, cutting into Americans' budgets for eating out, holiday gifts and other discretionary purchases. Higher energy costs can also affect the price of goods and services manufactured, shipped or airlifted. Airfares rose nearly 5% in August. Persistent inflation could put pressure on the Federal Reserve to keep interest rates higher for longer to further cool the U.S. economy.

"These include strikes, the government shutdown, the resumption of student loan payments, higher long-term interest rates, and oil price shocks," Fed Chairman Jerome Powell said Wednesday when asked about external factors that could affect the economy. "We are facing all this in an economy that appears to have strong momentum," Powell said. That's where we start. But we do face so many risks."