Circle your calendars: Sept. 15, 2009, is when the recession will end, according to Mark Zandi, chief economist and co-founder of Moody's Economy.com.

Zandi told a crowd of nearly 350 people on Friday morning that while certain elements of the economy will bottom out before or after that date, Sept. 15 is his prediction for the official end of the current recession.

He noted, however, that his timeline and recession-ending date is "subject to revision."

"Not that the economy will come roaring back in 2010, but the decline in economic activity will abate at that point," Zandi said during his keynote presentation before the 23rd annual Economic Report to the Governor was announced.

Zandi said the current recession will be the worst since World War II and last 21 months — twice as long as the 10-month recession average.

"The outlook, at least through '09 to 2010, is extraordinarily difficult. The first half of '09 will be very painful. The second half of '09 will be just painful," he said. "2010 will be uncomfortable. It really won't be until 2011 before we begin feeling much better about the health of the economy."

The downturn is reflected most in job markets, with 2.6 million jobs lost during the past year. Zandi predicts 5 million will be lost during the recession's run, with a 9 percent national unemployment rate in early 2010, contrasting with a pre-recession rate of 4.4 percent.

"That is the biggest increase in the unemployment rate in any recession we've experienced since World War II," he said. "That is probably the best measure of the severity of the economic downturn."

People are in "financial panic," he said. "There's an element of sheer fear and irrationality to what we're going through. People are literally putting money into the mattress, selling stocks, selling homes and other assets and going into cash."

"The panic is past its worst, but it continues on. And as long as it continues on, the risks to our economy are very significant," Zandi said.

The current credit crunch, he said, "is a significant weight" on economic activity. "Credit is the mother's milk of economic growth. Without credit, you don't get loans. As long as the financial system is in disarray, you're not going to get bond issues, and if lenders are tightening, the economy will struggle."

But reasons for optimism include lower energy costs, housing becoming more affordable — although home prices in Salt Lake City will continue to see declines — and policymakers taking action.

"We have been through lots of crises as a nation — natural disasters and wars and other economic crises — and when government is engaged and working aggressively, that has always signaled the end of those crises. And I think the fundamental reason for optimism is we're all on the same page," Zandi said.