The Bank of Canada signalled Tuesday that it's lowering its forecasts for economic growth in the second half of 2013 and possibly for next year, citing a more prudent consumer and an export sector that has yet to fully recover.

Senior deputy governor Tiff Macklem said the central bank no longer expects the July-September period to grow at a rate of 3.8 per cent as previously forecast.

Instead, the bank says the third quarter will likely show an economy that advanced at a more moderate pace of 2.0 per cent to 2.5 per cent, the same speed it now expects will continue in the fourth quarter. Previously, it had penciled in a 2.5 per cent expansion for the last three months of the year.

The Canadian dollar dipped on the news and was selling nearly a quarter of a cent lower in early afternoon trading.

A subdued bounce-back

The new projections were unveiled in an advance copy of a speech to be delivered by Macklem to a business audience in Toronto.

It was an unusual occurrence for the central bank, which normally issues new forecasts during its quarterly monetary policy reports. The next report will be issued on Oct. 23.

It was unclear why the bank decided to jump the gun, other than that early indicators have pointed to a more subdued bounce-back for the third quarter.

A report Monday on gross domestic product from Statistics Canada found the economy advanced by 0.6 per cent in July, a good monthly number but less than would be necessary to jump-start the quarter to a near four per cent surge.

Canadians cautious about spending

In the speech, Macklem explained that Canadians had become more cautious about spending, a welcome development giving that debt levels are already at record highs in relation to income.

"This is good news," Macklem said. "But this new-found and welcome household prudence is dampening growth. To replace this growth, we need a rotation in demand toward exports and business investment.

"Unfortunately, this rotation has proven elusive."

Macklem said the central bank still believes a revival in the U.S. economy will eventually lead to an increase in demand for Canadian products, but due to competitive pressures and continuing weak demand, it is taking longer. The delay has also restrained businesses from stepping up investments, a vicious negative cycle that is keeping our economy from returning to potential.

Although Macklem did not specifically refer to 2014, the analysis suggests that the bank may also be preparing to revise downward next year's 2.7 growth estimate, which many economists already consider overly rosy.

In an initial reaction to the speech, CIBC chief economist Avery Shenfeld said the bank may keep interest rates on hold until 2015.

No reference to U.S. shutdown

The senior deputy governor made no mention of the U.S. government shutdown and pending debt limit deadline, which economists say could sap as much as 1.5 per cent from U.S. growth if the crises persist. Such a scenario could also rebound on Canada, particularly in the key export sector.

Capital Economics has calculated the immediate hit to Canada would be in the range of three-tenths of one per cent, but that the consequences would be more severe if the impasse lasts and if Congress refuses to pass legislation to authorize payment of the government's debts, causing a technical deft default.

In a statement, Finance Minister Jim Flaherty also expressed concern with developments south of the border.

"This is a reminder that while Canada's economy remains strong, we are still vulnerable to uncertainties outside of our borders, especially in the U.S. and Europe."

Macklem's speech, his first since losing out to Stephen Poloz for the top job at the central bank in June, hardly painted a picture of a "strong" economy. Rather, the assessment was of an economy struggling to achieve lift-off, with a growth rate below the 2.5 per cent needed to return to full capacity.

Still, Macklem said the bank is holding out hope the a revival in U.S. demand will set the wheels in motion for stronger exports and beefed-up business investment, which in turn should lead to great productivity and competitiveness.

"Some recent surveys and other evidence, including the pick-up in firm creation, suggest that firms are becoming more optimistic," he said. "And once the sequence of stronger exports, rising confidence, increased investment and stronger productivity is launched, it could well gain traction faster than expected."