The real reason the NYPD named its legendary crime fighting computer tool CompStat was because it was snowing like crazy in the city the night of Feb. 11, 1994.

As the storm intensified, Sgt. Eugene Whyte, officer John Blancato and others were working on deadline at police headquarters on a new but rudimentary computer program. The iconoclastic deputy commissioner Jack Maple wanted the system to help cops get timely crime data. Nervous about the snow, Whyte told Blancato to hurry up.

"I can't leave until I put a file name on it," protested Blancato.

"Name it anything, let's go," responded Whyte. "We want to get out of here."

Groping for eight letters to name the file, Blancato quickly typed in the word CompStat, short for the phrase "Compare stats." The name stuck.

This year is the 20th anniversary of the advent of CompStat. From a modest beginning in a small office at NYPD headquarters -- and with the support of Maple and his then-commissioner William Bratton -- CompStat has changed the face of law enforcement. At its best, CompStat allows cops to track crime and compare performance but also to react quickly to changing situations.

Hundreds of police agencies use a CompStat system in some form. It is the one advance Bratton and his staff credited with helping the NYPD put together record-breaking declines in crime over the past two decades.

"CompStat was one of the most revolutionary developments in policing in the last century," said Vincent Henry, a former NYPD officer who worked with Bratton and is now director of the Homeland Security Management Institute at Long Island University. "It was revolutionary, it changed the way people do business, changed the way police think about crime."

CompStat has also spawned controversy and has been blamed by some academics and critics for what they see as an overreliance by the NYPD on data to show progress against crime. The result had been falsification of crime statistics by some commanders, something Bratton said is "misapplication" of CompStat and the road to professional suicide.

"The quickest way to get killed in CompStat [meetings] was if you were playing around with the numbers," said Bratton.

On Tuesday, Bratton will rename the massive CompStat command and control center on the eighth floor of police headquarters after Maple, who died in 2001 from colon cancer. Hundreds of law enforcement and government officials, as well as actor Tom Selleck, star of the NYPD-inspired drama series "Blue Bloods," are expected to attend.

A commemorative medal is being minted for the occasion. One side will have a representation of the three things that came to symbolize Maple: a Homburg hat, a bow tie and distinctive two-toned Allen Edmonds spectator shoes.

In Maple, Bratton found a kindred spirit. Both men bonded over dinners at the River Café and the now-defunct Elaine's at which they shared the belief that cops needed timely and accurate intelligence. In the 1990s, New York City needed CompStat, said Bratton. Cops didn't want to be just report-takers.

"Police felt they had a mission and that mission was to take the city back from the crime, the fear and degradation that was destroying and that nobody thought could be done," recalled Bratton.

Before CompStat, crime data inside the NYPD was kept in bureaucratic silos, computer systems that couldn't communicate with each other, recalled Whyte.

"That was the mentality of this place," remembered Bratton. "Guard everything -- information was power. So nobody wanted to share information."

At the precinct level, commanders often were flying blind, relying on printed reports that were six to eight months out of date.

But CompStat now works across the entire NYPD. In 1994 Bratton's first CompStat reports were relatively crude. Today, Bratton's executive conference room on the 14th floor is tied in to a wide array of computers and crime-mapping screens.

Maple, a former transit cop, had Bratton's blessing to develop CompStat. By Feb. 15, 1994, the first 10 rudimentary CompStat books of statistics were released. The first volumes were simply a count of the seven major felonies.

A few months later Maple and then-chief of patrol Louis Anemone came up with the idea of calling in borough commanders to police headquarters to go over robbery trends. The first meeting on April 6, 1994, was a disaster with no one prepared, remembered Whyte.

Beginning on April 15, 1994, the department started having a series of weekly Compstat meetings that became legendary in the media for how commanders were sometimes raked over the coals.

But eventually the meetings became more collegial.

After Bratton left in mid-1995, CompStat remained a part of the NYPD. With a data-hungry Ray Kelly as police commissioner, CompStat flourished.

Today, the department's immense capacity for using data allows it to quickly react to changing crime situations and observe events in real time. Hand-held devices and tablets give cops on the beat quick access to information.

CompStat's popularity in law enforcement has inspired other police departments. But the results have not always been as successful, said Henry.

"A lot of departments don't use it right, or only a portion of it," Bratton said.

Reliance on CompStat has also been blamed as the source of pressure to keep low crime numbers, sometimes resulting in police commanders cooking the books. In the face of such criticism, Kelly commissioned an independent report in 2013 that revealed some misclassification of offenses but essentially accurate accounting of crime.

The report also noted that about two dozen officers between 2002 and 2011 had been disciplined for related misconduct.

After two decades, CompStat is part of the fabric of the NYPD. It got that way, many police experts agreed, because of Maple's vision, personality and drive.

Said Bratton: "I gave Jack a stage to perform on, he got out there with his top hat and cane and put on quite a show."