Saddam Hussein, the United Nations and the Federal Reserve Board may be teaming up to unwittingly create a brief window of opportunity for American mortgage refinancers and new borrowers early this winter.

That's the view of top mortgage-market analysts who have been trying to pinpoint the next bottom in the interest-rate cycle. If their reasoning sounds right to you -- and you've been thinking of either refinancing or taking out a mortgage on a new home -- you ought to get ready to act.

One of the market's shrewdest observers, Lewis S. Ranieri, chairman of Ranieri, Wilson & Co., said, "Personally, I would hold off {on nailing down a refinancing or new mortgage-loan commitment} until mid-December or early January." Ranieri pioneered the development of the international mortgage-securities industry while at Salomon Brothers Inc. in the 1980s. He now operates savings and loans and mortgage companies from New York and Texas.

Fixed-rate 30-year loans in many cities could dip as low as 9.5 percent by January, Ranieri said, thanks to credit-easing steps by the Federal Reserve Board. Fed Chairman Alan Greenspan told a congressional committee last week that the national economy is turning in weaker numbers than he had anticipated. Although he stopped short of promising Fed intervention to lower rates soon, such a move is now widely expected on Wall Street.

Anemic demand for new mortgages in a recessionary, end-of-the-year economy will also tend to nudge rates down from their current level, according to such analysts as Paul Havemann, vice president of HSH Associates, the nation's largest mortgage rate-monitoring service. HSH tracks fixed and adjustable-rate quotes at 2,000 banks, S&Ls and mortgage firms across the country.

"Rates have been floating down for five weeks," Havemann said. "But consumers haven't been borrowing mortgage money. I think people are sitting back waiting or they're just scared of doing anything at all with the Persian Gulf situation the way it is."

Havemann's rate-trackers reported that average national fixed rates for 30-year conventional mortgages finally broke the 10 percent barrier last week. The average quote nationwide on Nov. 29 was 9.9 percent, plus 2.2 points upfront. (A point equals 1 percent of the mortgage amount and usually is paid at settlement to the lender as interest in advance.)

Fifteen-year, fixed-rate loans went for an average 9.7 percent plus 2.1 points. First-year quotes on one-year adjustables averaged 8.1 percent plus 2 points.

Some markets already are considerably lower than the national average. Dallas lenders, for instance, last week quoted an average 9.66 percent plus 2.8 points on 30-year mortgages. Atlanta lenders were at 9.67 percent plus 2.6 points, Chicago and Cleveland were at 9.79 plus 2.7 and 2.4 points, respectively.

Ranieri, Havemann and other analysts agree about the event that will slam shut the rate window that's currently opening: the outbreak of war in the Middle East. "When the shooting starts -- if it starts -- then rates are going to take a big spike up," Havemann said. "It'll be a panic reaction by the capital markets, along with panic reactions in the oil market."

The United Nations's Jan. 15 deadline to Saddam Hussein, Havemann said, could be a tripwire for mortgage borrowers as well. If fighting breaks out shortly after that date -- or if the capital markets see it as inevitable before Jan. 15 -- "That's when the window will close."

So what do you do if you've been waiting for the opportune moment to plunge into the mortgage market? If you're buying a new or resale home, do some energetic rate-shopping sooner rather than later during December. Tell prospective lenders that you want the option to "lock in" your rate sometime during the coming 45 days. Final loan closing could then be in February or later.

If you're potentially in the refinancing market, don't be immobilized by the old "refi rule" that says you've always got to drop a full 2 percentage points before refinancing makes sense. That rule was invented by lenders who want you to hold on to your high-rate mortgage for as long as possible.

The key to the refinancing game is understanding the interplay among your current rate, your new rate and points, how long you plan to stay with the new loan and your income-tax rate. The longer you stay in your house, the greater the likelihood that even a modest decrease in your rate will overcome the transaction costs of refinancing, and thus more than pay for itself.

Anyone with a 10.5 percent or higher rate loan, adjustable or fixed, should explore refinancing in the current market.