One week ago, unimaginable misfortune struck this proud capital of chill: It warmed up.

Instead of January's usual nose-nipping, toes-numbing, sub-freezing cold, the mercury climbed to a balmy 40 degrees and more or less stayed there.

Now, city officials' vaulting dreams of building the world's tallest ice palace have melted.

Ambitiously designed to commemorate the 100th anniversary of St. Paul's first winter carnival in 1886, the dream palace was intended to soar 150 feet into the wintry sky, a confection of seven smooth towers, battlements, ramparts and buttresses.

To be built on a small island on frozen Lake Phelan, a recreation park northeast of downtown, the palace would be "a pure fantasy . . . an abstract expression of ice," according to its designer, architect Karl Ermani.

But yesterday it was disclosed that the tallest tower will not be built and the palace will rise just 120 feet -- 20 feet shy of the tallest ice castle on record.

The scaling down will reduce the number of ice blocks in the structure from 15,000 to about 6,000.

The shrinkage is aimed at cutting construction time to make up for earlier delays caused, somewhat perversely, by unseasonably cold temperatures that slowed the pouring of a concrete pad for the palace.

Whatever its eventual height and size, the ice palace of St. Paul will serve as the centerpiece of the city's two-week Winter Carnival, a mid-winter celebration of torchlight parades, hot-air balloon races, auto races on ice, ice-carving contests and other frosty enterprises.

Winter carnivals took shape here after a wandering New York journalist, perhaps blown off course by January blasts in 1880, blustered to his pampered eastern readers that St. Paul was "another Siberia, unfit for human habitation in winter."

It was perhaps less a question of journalistic accuracy and more a matter of wounded pride that drove St. Paulians to seek revenge against sissies from another time zone by choosing the coldest two weeks of the winter for their carnival.

There have been 17 ice palaces built here in the years since. The 1888 palace, at 140 feet, was the tallest; the 1937 palace, although just 70 feet high, boasted an elevator. But the weather was just as mulish in earlier times as it is this winter. Over the years, five palaces melted before they could be finished. They included the 1942 creation, which reached eight feet before turning to water.

The last major palace was a 37-foot model, built 10 years ago.

The long drought in ice palaces and the fact that this is the centennial year of the carnival whetted civic leaders' appetites for "something extraordinary," as carnival chairman Charlie Hall said recently.

The city is getting more than $1 million in volunteer labor, construction machinery and ice-cutting, -hauling and -handling gear to build the palace. Ice blocks the size of desks and weighing 600 to 800 pounds are the basic building material.

Retired "ice harvesters," septuagenarians who made their living cutting ice for refrigerated rail cars and other summer needs, preside over much of the work. The blocks are freed from a fenced-off section of Lake Phelan, lifted by crane onto a wooden runway and prodded and slid several hundred yards to the castle grounds.

There, other cranes lift the blocks into place, as workers slop slush into the cracks for mortar.

On good days, when the temperature stayed comfortably below freezing, the palace seemed to be taking speedy shape. But when the sun came out last week -- and stayed out -- troubles began.

Strangely webbed fissures began appearing in the ice blocks facing south. So Thomas Keller, whose Austin Keller Construction Co. is donating time and machinery to build the castle, ordered the south ramparts swathed in white plastic film and packed with dry ice to keep them from melting.

But by this week, even those attempts to stave off the sun had failed, and tests showed that some of the ice blocks were losing strength.

"It's terrible, a very big disappointment," said Michael Shekhner, the structural engineer who designed the palace with architect Ermani. Both men work for Ellerbe Architects, a St. Paul firm with a worldwide practice that won the design competition for the palace and is supervising its construction.

"But the weather's got to change if they are going to get the palace finished," said Larry Millett, a reporter for the St. Paul Pioneer Press-Dispatch, who has been covering the icy saga.

And there's the rub, reports forecaster Ron Willis of the National Weather Service's Minneapolis office. "It's just unseasonably warm," he said. And his forecast is for another three-to-five days of continued high temperatures.

"It's a beautiful design," mused Shekhner.

Ice or ice water, castle or no castle, St. Paul's centennial Winter Carnival will open Wednesday and end Feb. 9.